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Isuzu Trooper Maintenance and Repair



  • 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??
  • 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
  • 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
  • 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 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.
  • 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
  • I replaced the alternator it didn't help the dash lights are still on. :confuse:
  • atfdmikeatfdmike 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
  • 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 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.
  • 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 Posts: 414
    It would help to know what year, model and particular engine you have in order to offer an opinion.
  • 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....
  • 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.
  • 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 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.
  • 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 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
  • 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........
  • 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:
  • Is there a fuse box location besides the one in the engine compartment.????????
  • atfdmikeatfdmike Posts: 414
    As far as I can tell from my manual, your Trooper II only has the fuse block in the engine compartment.
  • Hello, I have a 94 tropper and when i slow down, even if the brakes are not used and i come to a rolling stop, i hear a grinding/clunking sound. Also, while driving i hear a high pitch grind. I checked the u-joints and they are secure but they have excessive grease build up. Hope this information helps to detect the problem. Any information will be appriciated. Thanks
  • guestguest Posts: 770
    Hello Isuzu group , my thanks for allowing me entry to your boards. I have a big porblem and questions. Actually it is my wifes Isuzu. She bought the Trooper used about 3 years ago from a local new and used car dealership. The Trooper was and is in good shape ,oil has been kept changed and all seemed well . The vehicle is a 2001 model with about 65,000 original miles. She drives it to and from work locally and some weekend shopping. Yesterday she left for work and while on the road suddenly the Trooper stopped running. She said it made no noises ,no dash light came on and then just before it stopped running she heard a squeal. She drifted to the shoulder of the road and I had it towed to a local garage . We were shocked when the garage phoned today to say the motor had locked up on the vehicle. The oil had apparently ran out on the road where the truck stopped running no one knows why . The wife is an easy driver , has not run the truck hard. Can anyone tell me if such major failure is common with this lower mileage ? Has Isuzu had any issues with the 2001 Trooper engines? My guess is a year 2001 with say 65,000 is out of warranty for a motor ? Many Thanks to all who reply, Randy
  • Hello Boards , Here is an update in the 2001 Trooper . We had the Trooper towed home from the garage as is yesterday. This is the first I have had the chance to actually look at the truck. As mentioned the Garage had said the motor was locked up and blown. I looked at the engine today and have found this to be seemingly inaccurate. The engine turns over with the key but is not firing for obvious visible reasons. Here is what I can see happened and why this happened I do not know. The timing pulley itself on the cam actually shattered ,it is gone except for one piece of it about 3 inches long which I found in the engine compartment. This of course also broke the plastic timing belt cover to pieces and the force of this moved the serpentine belt partially off of its pulleys. I also checked and my wife was a little off on the mileage . The Trooper has 68,136 miles on it to be accurate. The timing belt is still completely intact and not broken . The timing pulley though again is totaled and mostly gone? I would not have beleived this had I not seen it. The engine turns over with the key ,no odd sounds ,no clunking etc simply not firing as their is no timing. We are the second owner. Any suggestions ? anyone know if Isuzu would cover this for a second owner of a 2001 with 68,000 miles ? Many Many Thanks to all who reply , Randy
  • atfdmikeatfdmike Posts: 414
    Hi, sorry to hear about the problem with your Trooper. I have an older Trooper, but I believe your 2001 is a non-interference engine which means that when the pulley broke and the timing was catastrophically off there should have been no damage due to the pulley/belt problem. What I would wonder is why the cam gear broke in the first place. I would start by pulling the valve cover and checking the valve stems for damaged or bent or Missing valve. The cam gear which is broken may be jammed or obstructed by a broken spring, valve stem, etc; My thinking is that a valve may have broken or gotten stuck in a position that caused the camshaft to seize or bind, at which point the gear broke due to the stress on it. Another possibility would be a seized cam bearing, which would also freeze the cam . I could be way off, but it is a place to start. I would be leery of trying to just put a new gear on the cam and resetting the belt, etc on the chance that that is all that is needed. I am no expert, and what I suggest may be more work than you hoped for. Of course, you could replace the gear and try it a lot cheaper and easier that tearing into it, but I am not that lucky. Good luck, let us know what you find or decide to do!
  • Hello Mike . Many thanks for the tips. I know what you mean as I doubt I could be so lucky as for just another puller:) I may peek inside and see what I can see. If it looks to bad we may just do the push pull drag in trade thing where the lot give us a decent trade in price even with a locked up engine. I had a friend who is ase cert. and has his own garage call a place about the engine. I believe they are a big name engine rebuilder . An Isuzu 3.5 engine remaned is right around $5000.00 . The real downside is this builder also said that the 3 series Isuzu engines are junk. This was their exact words. According to the friend this place is like JASPER and he says their word is Gold in the auto circles . Given this I may not even bother with an engine . LOL The wife says she will take one of the new Isuzus that replaced the Trooper . I told her I think not after what I was just told about Isuzu engines . Whatever happened to the good old days of quality engines with no computers. The days when the cams actually spun on bearing instead of the bare surface such as the case with Isuzus 3.5 I told the wife to drive the spare car for now but I also hold my breath on that one . It is a 2001 Cadillac Catera with only 39,000 miles on it . Problem is the Catera have a truly lousy mechanical reputation which is why I only drive it on a limited basis when needed.My luck ,the Catera will develop a 10,000 problem as she uses it for now :)Could be worse though I keep three other cars in the garage ( 1969 Porsche 911T , 1970 Porsche 911E and a 1975 Benz 450 SL , all low mile originals . If the Catera should fault she'll then want in the Garage to pick lol not a good thing. It would then be hello enterprise rental car and she would be saying ,why won;t you let me drive the other cars. take care Mike and many many thanks again. Randy
  • wlbrown9wlbrown9 Posts: 867
    Hum, so it actually turns over but does not fire? If there were major damange, would it turn over at all? Or would there be real bad sounds when it turned over? Maybe you will get lucky. Good luck.
  • Point of trivia: The Isuzu Trooper and Caddilac Caterra share the same transmission. A GM transmission from France. Different gear ratios though. Same transmission is in assorted BMWs.
    I have owned a 1984, 1995, and 2001 Trooper. All have been super reliable for a total of over 400K miles. I have been told by my Isuzu specialist mechanic to keep up the maintenance because a rebuild or replacement would be very expensive. For me so far, no failures other than a few minor externals like a power steering idler pully on the 1984, head gasket small leak on 2001, EGR valve on 2001, and the tendency to lifter tick if the oil was dirty on the 1995. All were easy fix with parts in stock.
  • Hello everyone...

    My vehicle is a 1993 Isuzu Trooper LS 5sp with 180,000KM. Lately I have been having a problem with the check engine light coming on. Aside from oil changes, I'm unsure when it was last serviced as I bout it around 15,000KM ago.

    The light will come on anywhere between 10 and 30 minutes after I start driving. If I come to a stop, the light goes out, but returns when I start moving again. I have tried to flash the codes, but it shows no codes in memory. The light will stay on until I stop driving, but will not come on again if I shut down and re-start the car.

    I haven't yet tried putting the clutch in while moving to se if the light is speed or RPM triggered (or neither).

    Any ideas?

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