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Isuzu Trooper Maintenance and Repair

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


  • mjtankmjtank 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 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.
  • 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 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.
  • 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 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 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=
  • 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 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 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 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 Posts: 843
    I think you have an air leak into the intake maniold that bypasses the throttle.
  • qha000qha000 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 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=
  • 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 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 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 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
  • 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 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 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?
  • 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 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 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 .
  • 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.
  • 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.
  • 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!
  • 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.

  • 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?

  • Sent it to Dealer and told me low speed transmission sensor is bad. Changed it. $550 :cry:
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