Isuzu Trooper Maintenance and Repair

tidestertidester Member Posts: 10,059
Got problems? Got solutions? This is the place to talk about them!


  • mjtankmjtank Member Posts: 1
    I have a 99 trooper. I have noticed as of late that the idle will "take off" to around 2000 RPM. I have disconnected and reconnected the two sensors that are right up front by the throttle linkage and it worked, I think by coincidence. It could have been by shutting the truck off. Anyone have any ideas as to what might be happening.
  • lostlost Member Posts: 64
    Check your intake manifold gaskets for cracks. Put your ear near the intake manifold while the engine is running and listen for a hissing sound. This is a common problem for this engine. I have changed out both the left and right side gasgets in about 2 hours.
  • jukbxhrojukbxhro Member Posts: 5
    I am a proud owner of a babied 99 Trooper. However lately at my 85K mark my SUV has started Hard Shifting. It usually only does it once in a while in the morning about my first 15 minutes of the commute. I started letting it warm up longer about 3-5 minutes, that seemed to help a lot. I have taken it to two different AAMCO places and they say nothing is wrong with it. The computer is referencing no misfires or any information about something being wrong. About 2K miles ago I had the fuel pump replaced. That is the first problem I've had since I bought it in 99. Well now it seems to be getting worse - of course, it will now sometimes hard shift in the evening on the way home and sometimes no matter how long it warms up. I am terrified that something is horribly wrong and AAMCO doesn't know their butt from a hole in the ground. I need some advise. Should I be worried? And what can I do about it? Sometimes it shifts so hard I actually get shifted in my seat.. PLEASE HELP!!! :cry:
  • lostlost Member Posts: 64
    You need to check the Transmission Mode switch assembly to see if water has gotten inside. Have you noticed if the gear selection display on your instrument panel is dim or flickering when you shift from park to drive? The mode selection switch is located on the drivers side of the transmission ,it has a heat shield attached to it to protect it from the exhaust pipe that runs right next to it.
    I had the same problem as you are having now, I removed the switch assy from the transmission (held on by 3 small bolts) and one electrical connection. I dismantled the switch and found that all the grease inside had dried up and the switch contacts were shorting on each other. I cleaned out the switch and relubricated it with dielectric grease . Make sure to install the switch exactly as you found it as the position of the switch is adjustable and Very important as it tells the computer what gear you have selected. Hope this helps.
  • jonah75erjonah75er Member Posts: 1
    I`m a new be to this group. Checked out group and decided to join. have a 91 isuzu trooper 2.8 v-6 5spd,4x4.Had problem`s with fuel pump. Installed a new fuel pump and fuel line. Truck will turn over,but it won`t start,has fuel going to T.B.I.But if you put gas in will fire up and run until gas in t.b.i. is burn`t up .Before i changed fuel pump,it acted like it was running out of gas,jerking,stalling.I have a half of tank of gas in vechicle.This is my first problem with a trooper with this kind of problem`s.Any suggestion`s or help would be greatly appreciated.Thank you
  • atfdmikeatfdmike Member Posts: 414
    Hi, You don't mention the fuel filter in your post, but it should be changed too. At the TB there is a fitting to attach a fuel pressure guage.A sketch is here:!v=
    You can check the fuel pressure (carefully) to see if you are getting the correct pressure at TB. There is a pressure regulating valve that could also be at fault
    Start engine and idle.
    Disconnect fuel pressure regulator vacuum hose and plug. Fuel pressure should be 294 kPa (42 psi)
    Reconnect hose at regulator. Fuel pressure should be 245 kPa (35 psi)
    Disconnect vacuum hose from regulator and plug it.
    Turn engine off and observe pressure reading. Fuel pressure should remain approximately 245 kPa (35 psi) for four (4) minutes.
    Looks like you should have 35 pounds of pressure at rest. Remember that without the engine running, the fuel pump may only be on for as little as 2 seconds when the key is turned on. There are previous posts that show how to energise the pump directly for test purposes if you do not already know how to do this.
    1991 Isuzu Truck Trooper II L4-2559cc 2.6L SOHC (4ZE1)
    Vehicle Level Powertrain Management Fuel Delivery and Air Induction Description and Operation Fuel Injection System
    Fuel Injection System
    The multi-point electronic fuel injection system consists of the ECM, various engine condition and operation sensors and the fuel system. The main control sensor is the oxygen sensor. Utilizing these inputs, the ECM calculates fuel injection quantity and timing. Because injector valve opening is a constant and fuel pressure is regulated in relation to intake manifold pressure, the ECM controls injection quantity by varying the duration of injector "ON" time.

    Fuel Injector

    The injectors are "ON/OFF" solenoid valves installed one per cylinder on the intake manifold. The ECM sends pulses to energize (open) the injectors for varying lengths of time depending on its fuel requirement calculations, thereby controlling air/fuel ratio under a wide range of operating conditions.

    .Let us know what you find. Hope this helps.
  • atfdmikeatfdmike Member Posts: 414
    My sincerest apologies for posting the wrong engine info in the previous post. I should not offer advice so early in the morning. I reread your post and saw my error. Previous post was for the four cylinder. I have given links to the diagnosis charts for your engine (V6) below. I believe the fuel pressures are same, but there is no fuel tap to attach a guage to on the V6. There may be codes stored because the V6 employed a different ECM than the 4 cyl.

    The "Check Engine" light displays trouble codes that are stored in ECM memory. To activate the Diagnostic mode, a special connector located in the center console is utilized. When the ALDL (assembly line diagnostic link) connector is jumpered between terminals "A" and "B" with the ignition "ON" and the engine not running, the light will flash any stored codes.

    The first code to display should be code 12. This indicates that the self-diagnostics are functioning and is not a trouble code. The code 12 display is a flash followed by a short pause, then two flashes followed by a longer pause. If other codes are present, they will display in the same manner after code 12 has flashed three times. For example, the code 23 display is two flashes followed by a short pause, then three flashes followed by a longer pause. Each stored code is displayed three times, starting with the lowest in numerical order. Code 12 will repeat when all codes have shown. If no codes are stored, code 12 will display repeatedly until Diagnostic mode is exited by removal of the ALDL jumper wire. Remove the jumper wire before attempting to start the engine.

    To allow checking circuits which may be difficult to energize without driving the vehicle and being under particular operating conditions, all ECM controlled relays and solenoids (except fuel pump relay) are energized in Diagnostic mode.
    "Scan" tools also utilize the ALDL connector to access system diagnostic information. The use of a "Scan" tool is required to perform many of the tests under TROUBLE CODE COMPONENTS. here is link to ALDL pin locations.!v=

    I hope this helps.!v=!v=!v=!v=
  • jukbxhrojukbxhro Member Posts: 5
    That sounds EXACTLY what is going on. I can't wait to run home tonight and check it out. Man you ARE MY HERO! ! ! Plus you just saved me a grand from the dealer I am sure. :)
  • qha000qha000 Member Posts: 3
    While driving yesterday the BRAKE, FUEL, O2, and BATTERY lights came on. Shortly after the idle started acting up and unstable. Any ideas what might the cause be? Thanks
  • atfdmikeatfdmike Member Posts: 414
    Hi, I've got a 94 Trooper and when the alternator went out on me, I got the same lights. Also, the heater/ac would no longer work. If this is the case with yours, you might check the output of the alternator with a voltmeter at the battery. It should be nominally 13.6 volts with the engine running, check at idle and around 1500 rpm. and a light load.....turning on headlights and A/C should cause voltage change too. If you only see 12 volts or less in any condition, chances are the alternator is bad.
    Hope this helps
  • qha000qha000 Member Posts: 3
    Well, the alternator checked OK but the battery was bad. So I changed it, it took care of the dash lights but the rpm jumps up and down and the engine sounds like it's running cold with 3500 rpm when idle (I can hear the hissing sound of the chocke). Any thoughts?
  • boxtrooperboxtrooper Member Posts: 843
    I think you have an air leak into the intake maniold that bypasses the throttle.
  • qha000qha000 Member Posts: 3
    I checked the vaccule lines and didn't see any obvious leaks. I do have a Calmini air flow system which is much noisier than the stock one but the rpm doesn't go below 3500 when idle. When I drive the truck, the idle start fluctuating between 1500 and 3000. Thanks for all the help.
  • atfdmikeatfdmike Member Posts: 414
    Make sure you check the boot on the accelerator cable...there was a recall because it would deteriorate and stick holding the accelerator cable so that the engine would not return to its' normal position when pressure was released. Can be dangerous if driving..... good luck.
    Here is link to picture!v=
  • mommygatormommygator Member Posts: 1
    New to this board, so Hello! Bought my used, nearly mint condition trooper 3 years ago. A couple of months ago, I let my trooper sit for a while and the battery died. Ever since then, we can't turn off the factory alarm system, no matter how much you toggle the button. As long as you unlocked (remote wore out a year ago) the door with the key and immediately got in and turned the car on, everything was fine. Yesterday, while shopping, I got in, turned the key on....doors locked and the alarm went nuts. Finally got out of the car, but had to wait till the battery ran completely down for it to shut up. Husband came, took off the positive cable, replaced it, and jumped us off. Car worked fine. This morning he cranked it before he left and it cranked fine. Then I went to take kids to school and it did the crazy trick again. Any ideas on how to stop this? (obviously there is no owner's manual-where to get one?) My kids say I have a poltergeist, but I'm hoping for a more logical answer :) Sorry for the length of the question.
  • atfdmikeatfdmike Member Posts: 414
    Hi, You can try ebay for an owners manual. I have a 94 and it took a while, but someone from this forum gave me the idea, and they do end up there. As far as your alarm, I have included a description of how it should work. ( The battery in your remote key fob can be replaced, too!)
    The anti theft alarm controller is solid state, but I would suggest checking each door switch, cleaning terminal and checking hood switch , are door lock actuators working right,too before messing with controller. They must all function properly for the system to work right. Also, you don't mention the alarm security light on your dash.....did it work when you got it, did it quit, etc; The more info y ou provide, the more people here will be able to help. Good luck

    1995 Isuzu Truck Trooper (4 Door) V6-3165cc 3.2L DOHC (6VD1)
    Vehicle Level Accessories and Optional Equipment Antitheft and Alarm Systems Description and Operation Anti-Theft System

    Anti-Theft System

    The Anti-theft System consists of the following components:
    Anti-theft controller
    Left and right door switches
    Left, right, and tailgate door key detect and tamper switches
    Tailgate switch
    Engine hood switch
    Door lock actuators
    Left and right front door lock switches
    Lighting relay
    Starter relay
    "ANTITHEFT" indicator light
    Anti-theft horn
    The arming sequence is initiated with the starter switch in the LOCK position and all doors closed. This results in all theft related switches to be open to ground. The "ANTITHEFT" indicator then flashes for about 30 seconds or until the arming sequence is completed. When the driver's door is locked using the door key, the door lock actuator internal switch will open, removing the ground signal from the anti-theft control unit input. Now all inputs to the anti-theft control unit are open to ground and the "ANTI-THEFT" indicator stays lit for about 8 seconds . The anti-theft system is now armed. If any of the theft related switches are grounded, the theft alarm is activated. The anti-theft controller does not allow the vehicle to be started by not applying ground to the starter relay. The anti-theft controller pulses a ground signal to the lighting relay causing the headlights to flash. At the same time, the anti-theft controller unit pulses a ground signal to the anti-theft horn, causing it to sound. The system alarm is cancelled when the anti-theft controller sees battery voltage at its ignition input or a ground signal at its key detect input.

    The circuit consists of the starter switch, anti-theft controller, anti-theft horn, front door and tailgate key switch (detect and tamper switch)~ door lock (& power window) switch, door lock actuator for each door, engine hood switch, clutch start switch (M/T), ANTI-THEFT indicator light and mode switch (A/T). The system operates as follows: After locking the starter switch and removing the starter key (this sets the alarm), if the door is unlocked in any way other than with the proper key, the headlights start flashing, the horn sounds, and the starter circuit is disabled. (However, the engine hood and all the doors must be locked and closed.)

    Once the system has been placed in the warning or alarm condition, it can be released only when the starter switch is shifted from "OFF" to "ACC" by the starter key, or when the lock of the front door or the tailgate is released (to activate the detect switch) by the starter key.
  • snmfeesnmfee Member Posts: 2
    Got 91 trooperII i can not find the ALDL link as noted. I have cleaned the injectors, replaced plugs, fixed a couple of bad wires. It ran great for about 10 miles. When I stopped it started skipping again. Got to different repair manuals both say check for codes, but cant find ALDL clip.
  • atfdmikeatfdmike Member Posts: 414
    Hi, I posted a diagram on at this location. Unfortunately, You will have to look at it there since I cannot seem to do anything else with it. I don't know if it is my settings or what??!! this is for the four cylinder engine. I think it may be different for 6 cyl. You can see that it is in console, about half way back and consists of two wire set. In the diagram, it is the lower set. Hope this helps
  • blrobisonblrobison Member Posts: 1
    This is the first time this ever happened to me. I just filled up the tank, I was driving for about an hour, and then the truck started acting like it was going to turn off but then got back to accelerating. After that it didnt do it again that day. Then the next day, I was driving and I went and filled up the tank again and then it started doing it again. And then when I pulled over in the fuel tank where you gas in the truck, started coming out of the tank thru the cap. and poured all over the ground. I then opened the cap and a bunch of pressure was coming out of the tank. I am wondering if anyone knows what that could be.
  • mrss396mrss396 Member Posts: 1
    My wife's Trooper has something wrong with the electric system. The battery and alternator are ok but something is draining the battery down while the vehicle is setting and not running. I detect a slight spark when I unhook and hook up the positive battery cable. Anyone got any ideas on this?

    Thanks, Rick
  • boxtrooperboxtrooper Member Posts: 843
    Dome lights on because of a bad door switch or not quite closed door? Or if the dome lights are specifically turned off, the lights in the bottom of the door panels? An aftermarket stereo is standby mode instead of off? Faulty ignition switch leaving power on in general?
  • tfreemantfreeman Member Posts: 1
    We have 63,000 miles on a 2001 Trooper LS (4cylinder) & have never had any problems until now. When you step on the gas the car won't go more than 20 to 30 mph. My son was doing driver trainer on the interstate going 70 then suddenly it drops down to 15 to 20 mph and won't go any faster. It's been doing this for a week. We took it into an auto repair and they said they called a "hotline" and said it was a wiring problem. They replaced a wire. It worked o.k. for about 48 hours and now has the same problem. We've taken it back in and they're saying "gee maybe its a computer problem, we're not sure". They've kept it for 2 days now. We live in the middle of nowhere in the midwest so there's no dealership to take it to. Has anyone heard of this problem before? I'd appreciate any input!
  • boxtrooperboxtrooper Member Posts: 843
    Do you have the 4 cylinder diesel? If you do, how did you get it into the USA? And what's your MPG?
    Or the 6 cylinder gasoline engine? I have not heard of a 4 cylinder gasoline 2001 Trooper.
  • spiveyspivey Member Posts: 1
    Hi - Long story short - Wife took the vehicle on 3 hour trip with tran fluid 2 quarts low. Transmission will only shift manually now. 1st through 3rd gears work manually with no fourth gear shift up when I go to D; just stays in 3rd. I can shift down from 3rd to 2nd to 1st with no problems. Placing the shifter in D starts the transmission in 3rd. It won't shift up or down out of 3rd. Somebody please tell me this is a simple problem to fix. This has been my 2nd Trooper - it now has 150K+ on it. Love this car :D .
  • atfdmikeatfdmike Member Posts: 414
    Hi, It is possible for you to check for trouble codes on your vehicle. If you get a code and need help, post again.

    1995 Isuzu Truck Trooper (2 Door) V6-3165cc 3.2L DOHC (6VD1)
    Vehicle Level Transmission and Drivetrain Transmission Control Systems Testing and Inspection Testing and Inspection Procedures Displaying and Reading Trouble Codes

    Displaying and Reading Trouble Codes
    This is a link to a diagram of locating the jumpers. .gif/photo/v./photo.jpg

    DTC can be displayed by the Transmission Control Module (TCM) by shorting together terminals 1 and 2 of the TCM Diagnosis Connector (C-92) located left side of left instrument panel (This grounds the TCM pin D16).

    After this, the CHECK TRANS Indicator will be OFF for 3.2 second and then will flash each DTC 3 times.
    When there are more than 9 flashes this means that the indicator is constantly flashing, OFF for 0.4 seconds, ON for 0.4 seconds. In this case there is no DTC stored in memory. To find the problem without a scan tool and without DTC GOTO WITHOUT DTC CHECK.
    When there are less than 9 flashes you will see DTC of 2 digits repeated 3 times each and when all codes have been displayed they are displayed again beginning from the first one.
    Do not care about the DTC order : if "21" is before "22" it does not matter.
    Write down all codes numbers and GOTO DTC CHECK.
    IF CHECK TRANS indicator is not flashing GOTO "CHECK TRANS" CHECK.
  • curbcheckcurbcheck Member Posts: 1
    I'm brand new here, so forgive me if I err hugely!
    I have a '93 Trooper who is my pride and joy. I have had her for 2 years, third owner. When I bought her I did some preventive maint. stuff (brakes, tires, timing belt, clutch,etc)--and she runs great. She's got 111k and my issue now is a fuel smell/leak in the engine compartment. Needless to say, she is parked. Other than the smell and obvious leak, she runs great (best in cold weather)no stalling nothing. We can't find the source of the leak. My questions: Is it about time for an overhaul? Should I consider an overhaul? Would an overhaul replace parts that might be causing the fuel leak? (I'm assuming it is something along the line of worn hoses and the like) Should I instead just concentrate on letting a mechanic find just the leak? I intend to keep this Trooper until the wheels fall off so an overhaul is just a matter of time. Please forgive my total inexperience with vehicles, this is my second car--and I'm quite attached to her.
  • atfdmikeatfdmike Member Posts: 414
    Hi, the gas smell could be from a variety of sources, but an overhaul might be overkill. The fuel system is pressurized by a pump in the fuel tank, and the pump only turns on for about 2 seconds when you first turn the key on. Then it will turn on when it sees oil pressure from the engine running or from cranking long enough to do same. That means that when your trooper is not running and just sitting, there may not be enough fuel pressure to spot a drip or pool of fuel, and if the engine is running the fuel may vaporize too fast to see due to the heat. The bottom line is the fuel system should be inspected from tank to fuel injector, and care must be taken to insure no injury to you or the vehicle. If you can't spot or isolate the location yourself, then a mechanic would be your best choice. Your trooper does not need an overhaul just to fix a leak. If you search this forum you will find many Troopers with far more miles than yours and no overhaul. The complexity of the fuel system with its' O-rings and connections may just be more than the casual car owner can handle. I hope this info helps you decide what to do. One owners opinion!
  • shaopengsunshaopengsun Member Posts: 17
    I found my 2000 trooper's Check Trans light on. At low speed, when I speed up slowly, I can feel the shake of the car. Anybody now the reason? Please help.

  • jimbilljimbill Member Posts: 2
    My '99 Trooper has been performing like a charm for all of her 136,000 miles. But on Labor Day, I had driven only about 100 yards out of my driveway when she bucked twice and stopped dead: the electrical system was instantaneously and completely flat. The rapair shop towed the Trooper and installed a new battery, and I went on my way. Then two weekends ago, she started bucking again on the Interstate and then lost almost all power. Towed again. This time the air mass sensor was replaced and away I went. For the past few days, the Trooper has been surging not only when the engine is under load but sometimes at normal speed on a flat roadway. The repair guys see no problem codes on the computer. I don't want to spend a lot of money unnecessarily, but I'd like to continue my long and happy relationship with this fine vehicle. Any ideas?

  • shaopengsunshaopengsun Member Posts: 17
    Sent it to Dealer and told me low speed transmission sensor is bad. Changed it. $550 :cry:
  • manobremanobre Member Posts: 3
    Our '96 Automatic Trooper needed a transmission replacement (lost reverse completely) and since then the replacement transmission has been nothing but problems, it runs fine for a while after the shop "fixes" it, then it acts up. Currently it seems like it's not downshifting back to 1st gear after reaching a certain speed or distance or both. When you come to a stop, then start up again, it feels like the truck is in 3rd gear...the mechanic can't figure it out...anybody??
  • atfdmikeatfdmike Member Posts: 414
    Hi, is there any chance that you have the winter switch in winter mode.....that option commands the trans to start in 3rd to increase traction when driving in slippery conditions?
    I have to wonder though, that if your original trans was OK except for reverse, then the new trans does not sound like it was built properly if you have had problems with it since installation.
    You might inquire if the mechanic used a scan tool to check for trouble codes that might be set in the transmission controller. Good luck
  • SchlichSchlich Member Posts: 6
    I spoke to a man the other day that had the same problem (battery drain) check the positive cable all the way ....his insulator had melted close to the head light causing a short to ground thus draining the battery upon sitting......good luck
  • SchlichSchlich Member Posts: 6
    My Brake ,Fuel and battery lights came on at the same time now wont go off and heater/ac fan wont work and it runs very rough please help.
  • sbcookesbcooke Member Posts: 2,297
    Don't forget about the standard intake manifold gasket problem, compression like issues could be attributed to this. Mine went at 40K miles, and I had to take it into the shop over and over and over and over again, because it didn't show codes and they couldn't recreate it from the parking spot to the garage bay. I finally had the service rep use it as a personal vehicle for a day and tell me what he failed the first time he took it out and was fixed the next day.
  • atfdmikeatfdmike Member Posts: 414
    It is a possibility that your alternator has gone bad. I had the same experience with my 94 trooper, and that is what was wrong. The dashboard lit up and the heater would not work. If it is your alternator, your battery is not being charged, which leads eventually to the engine quitting.
    Good luck
  • SchlichSchlich Member Posts: 6
    I replaced the alternator it didn't help the dash lights are still on. :confuse:
  • atfdmikeatfdmike Member Posts: 414
    Not to sound too defensive, but my previous post suggested a possible cause, not the sure reason. Did you have the original alternator checked before you replaced it? did your ac/heater fan start after you replaced the alternator? What engine do you have? Anyway, I did a search for possible technical service bulletins, and they follow. A big problem on Isuzus in general has been the electrical connectors. Apparently a lot of glitches can be caused by them. Checking your wiring harness and connectors might be a good start too.
    You can check for codes too, if you find any, post and an answer may be had, by:
    Connect white (test lead) and black (ground lead) wires that are branched from the fuel system control harness approximately 8 inches from ECM. (These leads can usually be found near the cigarette lighter and will be wrapped in green tape if they have never been disturbed). After the leads are connected, turn the ignition switch "On". The ``Check Engine'' lamp will flash appropriate trouble codes. The codes are indicated by pulsing of the lamp. Two pulses followed by a short time lapse, then three pulses would indicate a code 23 and so on. If only one trouble code is stored, the code will repeat continuously until test leads are disconnected. If more than one trouble code is stored, each code will repeat three times, starting with the lowest, then proceed to the next code. After all codes have been shown, the pattern will repeat itself. Refer to Fig. 4 for trouble code identification.
    Trouble codes can be cleared by removing voltage to the ECM for 10 seconds. After a fault has been corrected, remove the ECM fuse or disconnect battery cables for 10 seconds.

    Remember, these are just suggestions, you have to start somewhere, but sometimes they help.

    1985 Isuzu Truck Trooper II L4-1949cc (G200z)
    Vehicle Level Technical Service Bulletins All Technical Service Bulletins Alternator Wire - Damage/Shorting
    Alternator Wire - Damage/Shorting

    SB87-04-003 July 17, 1987 ELECTRICAL


    P'UP (KB) and Trooper II (KT) models with 4ZD1 engine.


    Several wires at the rear of the alternator are routed through a metal hold-down clamp. This clamp may damage the wires' insulation, eventually shorting or grounding the wires. Various electrical problems
    ranging from a blown fuse to failure to start may result from this damage.


    If the wires at the rear of the alternator are damaged, repair or replace the harness as required. Even if no damage is visible, wrap the affected area with tape or other protective material to prevent future damage.

    1985 Isuzu Truck Trooper II L4-1949cc (G200z)
    Vehicle Level Technical Service Bulletins All Technical Service Bulletins Engine - Backfires Excessively

    Engine - Backfires Excessively

    SB87-03-004 September 15, 1987 EMISSIONS

    1982-1987 P'UP (KB) and Trooper II (KT) models with gasoline engines.

    SERVICE INFORMATION - /photo/v./photo.jpg

    Excessive backfiring may be caused by a clogged gas vapor filter. Filter is located between the intake manifold and the mixture control valve.

    Replace the gas vapor filter as outlined in the appropriate Workshop Manual.


    Part No. Description

    8-94236-909-0 Gas Filter
  • gschwimmergschwimmer Member Posts: 3
    Hi, I just inherited this car from my daughter because of the following problem. You can be driving along when all of a sudden the dash lights go out and the speedometer goes to zero. This usually happens when you're slowing for a stop and than the motor dies. By popping the clutch it will restart and stay running with the check engine lite staying on. As I understand also, the O2 lite has been on for quite some time. The mechanic said the problem might be a speed control sensor. Is this something the average weekend mechanic should tackle? Thanks for any help
  • atfdmikeatfdmike Member Posts: 414
    You should get the trouble code that can be read by most part stores, or do it yourself by searching the Trooper forum for "pull trouble codes" or similar search. Once you have the code number, it will give you a better start point unless someone has had exactly the same experience, which does happen once in a while.
  • kdadmankdadman Member Posts: 2
    I had a local shop replace the water pump over the weekend because it involved the timing belt. The water pump is fine, but now there is a leak of either power steering fluid or engine oil. What is the most likely leak based on the repair done? I plan to have them take another look, but figure they will say "oh, we'd be happy to fix that leak for exchange for your other arm and leg"

    Help, I can't afford another costly repair!
  • atfdmikeatfdmike Member Posts: 414
    It would help to know what year, model and particular engine you have in order to offer an opinion.
  • manobremanobre Member Posts: 3
    It's not in Winter Mode (unless the switch is busted)..So we took it to a new Transmission guy who has been driving it for a few days with no troubles (of course!)and can't locate a problem, so he is taking it to someone who specializes in electrical problems....stay tuned....
  • SchlichSchlich Member Posts: 6
    Thanks Mike Ive got a lot to try and figure out now Engine is 1.9 G200z Fed. emissions I think(no O2 sensor)heater still wont work and today radio stopped working maybe a fuse ....Where is th ECM located one book says under center console others say under dash ???????? Very confused..... Your knowledge is greatly appreciated.
  • jimbilljimbill Member Posts: 2
    Thanks for the suggestion. I passed it along to the mechanic who's had the Trooper for two weeks without coming up with the nature of the problem and a solution. He says the truck will sit at idle all day without missing a stroke, but as soon as a load is put on the engine - driving it across his lot, for example - it begins to miss, lose power and flash the Check Engine light. Mr. AAA and I will meet at the repair shop at 5:00 PM to haul the Trooper off to another shop. Any additional thoughts anyone has in the meantime will sure be welcome.

  • atfdmikeatfdmike Member Posts: 414
    The manual for your vehicle shows an O2 sensor, so I am not sure about why yours would not have one, but regardless, I have not found a manual yet that shows where your ecm is located, which is quite unusual. The first reference I find to the ecm location is in 1987, where it is found behind the Right hand side of the instrument panel. The California ecm is also in that approximate location.
    I would definitely look at the fuses for your problem. Checking each with an ohm meter should help eliminate or reveal where the problem might lie.
    Isuzu constantly recommends that the connectors and electrical cable be inspected for breaks and corrosion problems. It would not hurt to inspect the connectors as well to see that no corrosion or disconnects are present. Good luck, hope this helps.

    1985 Isuzu Truck Trooper II L4-1949cc (G200z)
    Vehicle Level Technical Service Bulletins All Technical Service Bulletins Electrical - Inspect Connectors for Various Malfunctions

    Electrical - Inspect Connectors for Various Malfunctions

    Information IB05-04-S005

    Inspection Of All Related Wiring Harness Connections
    When Diagnosing Miscellaneous DTC's, Intermittent
    Driveability Concerns, Hard Start, No Start, Incorrect
    Gauges, Inoperative Air Conditioning Systems, Service
    Engine Soon Lamps Illuminated, 4WD Lamp Illuminated,
    Instrument Panel Gauges Inoperative, Cruise Inoperative


    Affected Vehicles

    All Isuzu Vehicles

    Service Information

    When servicing a vehicle for any type of customer concern, the following steps are imperative. Inspect and ensure the integrity of all related wiring harness connectors. If the wiring harness connectors are not properly put together or engaged before they are locked together, numerous types of intermittent conditions may occur, which may include any of the symptoms listed above and possibly others.

    The first step in any type of electrical diagnosis is a visual and physical inspection of the wiring harness connectors for integrity. Many times, the vehicle may be repaired just by disconnecting and reconnecting the connectors. As with all repairs to wiring harness connectors and terminals, a pull test of the terminals within the connector should be performed. A pull test is performed by inserting the proper size terminal test tool (not a paper clip) into the terminal to determine whether or not the terminal is making good contact, or whether the terminal has been damaged from the prior improper connection or lack of connection.

    NOTE : Most terminals used in current module connectors (ECM, BCM, and the like) are small O~64 mm sq terminals and can be damaged by probing with the wrong tool

    For example, if the Connector C2 of the engine wiring harness to the Powertrain Control Module (PCM) is not properly seated into the PCM:

    ^ The cam lock lever may close improperly.

    ^ The cam lock lever may even snap out of position.

    ^ The vehicle may have an intermittent condition with any one of the components which are controlled or monitored by the PCM.

    THE CAM LOCK LEVER IS DESIGNED TO PULL (OR ASSIST) THE CONNECTOR INTO ITS FINAL POSITION ONCE IT HAS BEEN PRESSED STRAIGHT INTO THE PCM HEADER PAST THE INITIAL DETENT, ALLOWING THE LEVER TO BE MOVED INTO THE LOCKED POSITION. It is not only a retainer but an assist during the connection process. When the wiring harness connector is properly connected to the PCM, a snap will be heard when the connector is in position to be fully seated. The cam lock lever may then be closed. The cam lock lever will then do its designated job as both an assist and ensuring the connector does not come apart due to vibration or other types of conditions found in vehicles as they travel down the highway.

    Remember, if a terminal (metal) or the connector (plastic) is damaged, they should be replaced. DO NOT replace the complete wfring harness assembly. Some harnesses are now on order restriction since most harness damage can be repaired.

    Replacement Terminals can be found in the J 38125 Terminal Repair Kit, which is available through Kent Moore at 1-800-654-6333.
    1985 Isuzu Truck Trooper II L4-1949cc (G200z)
    Vehicle Level Technical Service Bulletins All Technical Service Bulletins Alternator Wire - Damage/Shorting

    Alternator Wire - Damage/Shorting

    SB87-04-003 July 17, 1987 ELECTRICAL


    P'UP (KB) and Trooper II (KT) models with 4ZD1 engine.


    Several wires at the rear of the alternator are routed through a metal hold-down clamp. This clamp may damage the wires' insulation, eventually shorting or grounding the wires. Various electrical problems
    ranging from a blown fuse to failure to start may result from this damage.


    If the wires at the rear of the alternator are damaged, repair or replace the harness as required. Even if no damage is visible, wrap the affected area with tape or other protective material to prevent future damage.
  • gschwimmergschwimmer Member Posts: 3
    Found the trouble code to be #24 which indicates a speed sensor problem. Is there a way to check which one of the four might be defective? Thanks for the help.
  • atfdmikeatfdmike Member Posts: 414
    Hi, lots on this one. Some links included if I get this right! LOL I did the best I could with what you indicated. I am a little confused because there is a sensor on the trans, I think, that sends the pulses to the sensor in the dash. I could be all wrong, but I went in this direction because I could not find any other trouble code 24. I hope this helps and not confuses.

    NOTE: The vehicle speed sensor is not at the wheel itself, which is what code 24 refers to. It is NOT the wheel speed sensor which is found at each wheel. Codes for them are in the anti lock brake system module. Brake codes only seem to go from 1 to 15.
    1992 Isuzu Truck Trooper (4 Door) V6-3165cc 3.2L SOHC (6VD1)
    Vehicle Level Powertrain Management Computers and Control Systems Vehicle Speed Sensor Description and Operation Circuit Operation

    Circuit Operation

    The vehicle speed sensor generates a signal which indicates the vehicle speed to the speedometer. The speedometer consists of a vehicle speed sensor, an ammeter (needle movement), stepper motor (odometer) and a driving circuit (printed circuit board).

    The vehicle speed sensor is mounted to the transmission. The transmission pinion shaft rotates and generates four pulses per one rotation. The rate at which the pulses are generated indicates the vehicle speed. The vehicle speed sensor (incorporated in the speedometer) uses the pulses to control needle movement and sends vehicle speed information to the electronic control module (ECM) and the cruise control unit, The speedometer sends 4096 pulses per mile and the frequency indicates the vehicle speed.

    1992 Isuzu Truck Trooper (4 Door) V6-3165cc 3.2L SOHC (6VD1)
    Vehicle Level Powertrain Management Computers and Control Systems Vehicle Speed Sensor Testing and

    Remove the speedometer from the meter assembly, and measure the resistance value between the terminals. (Fig. 8-365)
    Replace the speedometer assembly when the result of inspection is found abnormal. TROOPER FORUM/dtc24vss.gif/pag- e/photo.html#pic

    1992 Isuzu Truck Trooper (4 Door) V6-3165cc 3.2L SOHC (6VD1)
    Vehicle Level Powertrain Management Computers and Control Systems Testing and Inspection Diagnostic Strategies Intermittant Check Procedure

    Intermittant Check Procedure

    "Intermittent" means that the "Check Engine" light comes on at times but does not stay on. Since codes may or may not be stored, the use of diagnostic charts could result in replacement of good parts.

    Most intermittent problems are caused by faulty electrical wiring or connections. Carefully check these potential causes:

    Poor mating of connector halves or terminals not fully seated in connector body.
    Deformed or damaged terminals. All connector terminals in problem circuit should be carefully reformed to increase contact tension.
    Poor terminal-to-wire connection. This requires removing terminal from connector body to properly check.
    Poor ground connections.
    If a visual check does not find the source of the problem, the vehicle may be driven with a voltmeter connected to a suspect circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit.
    An intermittent "Check Engine" light with no stored code may be caused by:

    Arcing at ignition coil, plug wires or spark plugs.
    Faulty power supply main relay.
    Poor power supply circuit connections.
    "Check Engine" light wire to Engine Control Module (ECM ) shorted to ground (circuit 22).
    Diagnostic test lead to ECM shorted to ground (circuit 24).
    Poor ECM ground connections at intake manifold.
    Electrical system interference caused by a defective relay, ECM driven solenoid or switch. These problems cause an electrical surge and normally occur when the faulty component is operated.
    Improper installation of accessories such as lights, sound systems, alarms, etc.

    1992 Isuzu Truck Trooper (4 Door) V6-3165cc 3.2L SOHC (6VD1)
    Vehicle Level Powertrain Management Computers and Control Systems Testing and Inspection Trouble Code Diagnostic Charts Code 24

    Code 24 TROOPER FORUM/dtc24a.gif/page/- photo.html#pic

    Circuit Description
    Vehicle speed information is provided to the Engine Control Module (ECM) by the Vehicle Speed Sensor (VSS), which alternately grounds WHT wire located in the meter panel when the drive wheels are turning. This pulsing action takes place 4096 times per mile, and the ECM will calculate vehicle speed based on the time between "pulses".

    Test Description
    Numbers below refer to circled numbers on the diagnostic c~art.

    Diagnostic Trouble Code (DTC) 24 will set if vehicle speed equals 0 mile per hour when:
    Engine speed is between 1600 and 1825 revolution per minute.
    Vehicle speed is indicated less than 1 Km/H (0.6 mile per hour).
    Manifold absolute pressure reading below 20.7 kPa.
    Low speed condition (low manifold absolute pressure voltage, high manifold vacuum)
    Not in park or neutral. (A/T)
    All conditions are met simultaneously for 1.5 seconds.
    No DTC 33 is set. These conditions are met during a road load deceleration. Disregard DTC 24 that sets when drive wheels are not turning.
    Diagnostic Aids
    "Scan tool" should indicate a vehicle speed whenever the drive wheels are turning greater than 0.6 mile per hour. Check the WHT wire for proper connections to be sure they are clean and tight and the harness is routed correctly.

    (A/T)- A faulty or misadjusted park/neutral position switch can result in a false DTC 24. Use a "Scan tool" and check for proper signal while in "DRIVE". Refer to CHART C-1A for park/neutral position switch check.

    If DTC 24 is intermittent,
    See: Diagnostic Strategies\Intermittant Check Procedure
  • manobremanobre Member Posts: 3
    UPDATE: we it made sense now that the guy who replaced the tranny couldn't find the problems that started after that, since a now 3rd mechanic to look at the truck (and drove it for a week till the problem cropped up again) has diagnosed it as bad catylitic converters choking out the engine...The trooper uses 2 of them and it looks like its going to cost around $1100 to put 2 new aftermarket converters on....I hope he's right........
  • SchlichSchlich Member Posts: 6
    I found a loose connect at the voltage regulator....this got the heater blower going again. lights still on in instrument panel (low fuel,battery,brake) running good though....Thanks for all your help........Stillconfused about lights though......??????????? :confuse:
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