Isuzu FAQ Rodeo and Trooper ( 1992, 1993, 1994, 1995.5, 1996, 1997)




If you're looking for a key word hit Ctrl-F and type in the word you would like to search for

Please email me at for additions and/or corrections.


The FAQ's that I created is about 95% Copy and Paste from other peoples posts at message forums. I have been reading Isuzu forums for about 8 years now. When I started to see there were a lot of the same problems I started to bookmark them. 

Therefore PLEASE use these suggestions on this site at your OWN RISK! 

Other questions?  Post your questions here: Automotiveforums





FireFox is free and is considered the best free, safe web browser available today.  Download it to keep your PC safe and searching for Isuzu information!

1.  Value ticking chatter
2. How to repack the front wheel bearings
3. Transmission problems
4. I have lower gas mileage what can I do?
5. Where can I purchase OEM parts?
6. Where can I purchase non OEM parts?
7. Where can I buy OEM used parts (mirrors, wheels, lights, body parts . . . )?
8. My Check engine light came on, where can I get it read at?
9. How and when should I replace my fuel filter?
10. I have knocking sound under idle and and/or around 2500 RPM, what can I do?
11.  I would like to replace my shocks, which one should I use?

12. I would like to buy a lift, bumpers, locker or other off road equipment, where can I buy it from?

13. What are some other Isuzu related Message forums?

14. How do I check the fluid level on my Tranny?

15.How to change the Rear diffy Fluid:

16. I would like to add a high flow air filter, which one?

17.  I want to replace my rubber bushings with poly ones, where can I buy some?

18.  What does the Power and Winter buttons do?

19.  How Performance Chips work?

20.  Transmission filter replacement and partial fluid swap?

21.  Electrical problems

22.  Opinions on Sea Foam

23.  Tips for removing the Alternator

24.  How to flush the radiator

25.  4wd always on or doesn't work

26.  Isuzu Engine Rebuild Kits:

27.  I need a new Exhaust (muffler; catback):

28  Looking for new center caps for your Isuzu wheels?

29. How to Reset the O2 light on a 91-94 


2. How to repack front wheel bearing, and when?

The manual states it should be done every 30k.  Others have stated that if you do not do deepwater crossings, or off-road in the mud you should be safe having them repacked when you have the front brakes replaced (stick with OEM pads, non OEM pads usually cause squeaking)  You can check to see if your bearings need to be repacked by: jacking the front wheel of the ground.  Grab onto the top and bottom of the wheel and tug back and forth.  If you have excessive play you should think about repacking the bearings.  I currently have 64k on my OEM pads and I have plenty of pad left (most folks get about 80-120k on there OEM pads; Stick with OEM pads when you replace them);  I had my bearings repacked at the dealer at 50k (I wanted to be safe)

How To article:


3. I have transmission  problems ( ECU code: P1870).

I have not read many posts on problems with the transmissions on the 96-03 Isuzu's.  Some common problems are that the tranny feels like it is slipping or it is shifting funny.  Many times this is due the a weak charging system (battery that is dieing, or the alternator is on the way out) or the electrical connection to the tranny is loose and dirty.  Also, others have noted that the funny feeling is due to low or dirty fluid. 

As for changing the tranny fluid, some are for flushing and others think that dropping the pan is the best way.  If you only drop the pan you will only be removing about 40% of the fluid, whereas the flush will pretty much replace all of the fluid.  There is a filter in the pan that should be replace at some point (your guess is as good as mine, but some have mentioned a 60-90K interval to replace the filter, but always change the fluid at least every 30K or sooner if you only do a partial fluid swap).  Fluid is cheap, but a new tranny costs about 3500 bucks, keep up on your tranny maintenance.


4.  I have lower gas mileage what can I do?

Might be due to, colder weather, winter grade gas, dirty PCV valve, dirty EGR, dirty fuel injectors, low tire pressure, larger then oem tire size, front and/or rear end needs to be aligned, dirty air filter, weak battery or weak alternator, dirty MAP sensor.  If you replace or clean any of the above pieces make sure you disconnect the battery for at least 15 minutes so the ECU will recalibrate itself.

5.  Where can I purchase OEM parts?

The guys at St Charles Isuzu, have the best prices on OEM parts (free shipping).  Mention you heard about them on the web and they will give you an additional discount.  Make sure you tell them your heard about them from the Ryan Endres' Isuzu FAQ page!

Toll Free: 800-727-8066

 Link to a website to look up part numbers:


6.  Where can I purchase non OEM parts?
Your internet wheel & tire source, Specializing in American 
Racing wheels, Motegi Wheels, Motto wheels, Riax wheels, Nitto tires, 
BF Goodrich tires, Yokohama tires & more. We also offer package deals 
shipped directly to your door.
OEM rims


7.  Where can I buy OEM used parts (mirrors, wheels, lights, body parts . . . )?


8.  My Check engine light came on, where can I get it read at?

Autozone, offers free code reading (the dealer will charge 60 bucks or more to read the codes.  The most common reason the CEL will come on is due to the gas cap is not tight enough or something else emission related CODE P 440

You can buy a cheap code reader for 30-50 bucks (often on sale) at Harbor Freight link to code reader .  If you take it to the dealer or another mechanic your going to pay 50-80 bucks for them to read your codes.  Nice piece of equipment to keep in your glove box or garage, so you can help others to diagnose there their troubles.


9.  How and when should I replace my fuel filter?

The manual states every 30k.  The OEM part cost less then 15 bucks and is located under the passenger's side door in the frame rail.  There is one bolt that keeps the filter in the bracket.  Also, to lessen gas spillage remove the gas cap, and you can pull the fuel pump fuse under the hood, start it up and run it until it dies (note this may cause a CEL, but by disconnecting the battery, recommended while removing the fuel filter, it will clear the codes).  Once you have removed the screw, move the hose clamps back and then you can remove the rubber fuel lines by twisting (twist them for a bit, 20 seconds) and then twist and pull them off.  This is about a 30-45 DIY job.


10.  I have knocking sound under idle and and/or around 2500 RPM, what can I do?

Commonly this is caused by the idler tensor that keeps the serpentine belt (the only you can easily see on the engine) taught that is bad – or – the timing belt tensor is bad.   Many times this is mistaken for Rod Knock and a mechanic will recommend a rebuild.


11.  I would like to replace my shocks, which one should I use?

Many folks have replaced there stock shocks with: monroe sensa-tracs

Place to buy shocks:

12.  I would like to buy a lift, bumpers, locker or other off road equipment, where can I buy it from?


13.  What are some other Isuzu related Message forums?




14.  How do I check the fluid level on my Tranny?

On the 1996-2004 (except Direct inject engines) the transmission is a sealed unit and doesn't have a dipstick.  To check it the truck should be warmed up but not excessively hot.  With the e-brake on an the wheels blocked, start the engine, place your shifter in neutral, remove the upper fill plug on the transmission and the fluid should just dribble out.

More tranny info

Post 1:
There are 2 nuts on the bottom of the tranny pan. The lower one is the drain. The one at the back of the pan in a recess is the filler. You need a hand pump or something similar to fill it to overflowing, then top it off with the engine running. Make sure you shift through the gears a couple of times when topping off.

Post 2:
You'll find two hex head plugs facing downward on the main/big tranny pan. The drain plug is the lower of the two that can be easily seen. The fill/level check plug is not so obvious. It's in the rear, right corner of the main pan, at the top of a semi-circle recess stamped deep into the pan. Both plugs are identical is size & dimension. As with any auto tranny, you have to check ATF level on a level surface, with the vehicle running & fully warmed up. ATF should just dribble out of the fill hole- indicating adequate level. If you check it with the truck off, ATF will POUR out of the hole since much of the ATF drains to the pan when the engine is off. You have to use a pump to get new ATF up & into the tranny.

15. How to change the Rear diffy Fluid:
Step by Step For Rodeo and Amigo:

1. Loosen the fill bolt (so it is easier to remove while the diffy cover is off) with a socket extension on your 
socket driver.

2. Loosen/ remove the track bar left hand side (I remove the nut from the leftside).

3. Place the pan below the diffy, loosen all the bolts, and smack it a couple of times with a rubber mallet. Let 
the oil start to drain a bit. (If you remove all the bolts at once you could end up taking an oil bath once your
 smack it with the rubber hammer).

4. Continue to loosen the bolts and drain the oil.

5. Once you have most of the oil out remove the cover. Clean the mating surfaces with a putty knife (if this is 
your first time since the truck was new you will find they used gasket maker stuff).

6. Replace the gasket with a paper gasket (if you want to use the make a gasket stuff that is fine but it will be 
a mess the next time it comes to change) Fel-Pro # RDS 6629 (7 bucks for the paper gasket at most autoparts stores
). The benefit of the paper gasket is the next time you change it it will just pop right off and no or little 
putty knife work is need. If you dab a little axle grease on the diffy housing it will help to keep the gasket
 in place.

5. Replace the cover, tighten it down (use a crossing pattern while tightening).

6. Fill with diffy fluid (note if you need oil with limited slip additive), a cheap 5buck hand pump will help to
 keep you clean (the hand pump screws onto the top of the oil bottle) and you can use it again and again over the

7. Tighten up the track bar and replace the fill bolt and your ready to roll!
My CD Changer decided to keep all six of my CDs hostage and than gave me a rude "Err3". I read a post on here a 
while back that says a fix is to whack it on the side immediately after hitting eject.
I'm not one to hit things like that, but in a moment of weakness - I did it.
Out they all came, and it works great now. I have tempted fate by putting them back.

16.  I would like to add a high flow air filter, which one?
Be careful not to over oil your filter or oil may have carried over to the mass airflow sensor (MAF) just
 downstream of the air filter box. A fouled MAF will cause the concerns you describe & does not always 
light up the check engine light. Pull out the MAF & CAREFULLY clean it with cotton swabs & electrical 
contact cleaner.
You have a couple of options.  You can remove your air box and add a Calimini or K&N cone air filter:
The problem with the the cone is that they will suck lots of hot dirty air from the engine bay.  Many have noted 
that they have seen a decrease in MPG (more air in = more gas)
Cone airfilter definitely makes the engine breathe better but more air in will mean more fuel to some degree but
 not to the extent that it will cause ANY problem. The computer and O2 sensors take care of adjusting the mix. 
There is a little bit of a torque loss with the cone filter due to the extra hot air ingested but a simple airbox
 ‘wall’ can be created to negate that. 
If you do change your filter (to high flow or OEM) make sure you reset the ECU, by disconnecting the battery for
 15 minutes.  The ECU will then relearn the new components that were added to give you the best MPG.
How to remove the air box:
there are 3 bolts to remove.2 inside the box and one on the outside (between the engine and the filter box). The
 one on the outside has a nut to remove and a stud to remove. Once you remove the bolts, the lower half of the 
filter box will come out. Look on the inside of the elbow and remove the s shaped thing by pushing down on it. Now 
you can remove the elbow. I had to use a screw driver to pry it out.
More Notes on hot air:
The outside air temp was 97, temp gauge only goes up to 160
Location filter box- 
10mph: 155
30mph: 112
60mph: 107

Location intake man- 
10mph: 160+
30mph: 160+
60mph: 150
Still want to use an unshielded cone filter?
If you do you should make your own heat shield
You can install a drop in panel filter:
Drop in K&N helps a bit but again the biggest restriction is the elbow through the fender - remove that before 
you invest in a drop in (pull the stock airbox and you will see the black plastic elbow). 
If you take the air box off to work on the elbow you will see that the elbow will actually come off without 
cutting! It takes a little shimmying to get the sucker off, but it WILL come off without any cutting.
Here's what Dave Chang did:
I cut open the air passage on the stock airbox and used a propane torch to seal the cut seams. Then I used a
3" PVC attached to a rubber coupling joint inserted into the hole in the fender to force the airbox to breathe
 air outside the engine bay. Running the K&N panel filter for stock airbox.
17.  I want to replace my rubber bushings with poly ones, where can I buy some?
Contact the guys in the below link to see if they can help (let me know if they can help because I do not know if they can):
Link to independent4x  Contact Matt, he has poly products, and see if he has what you need for your Isuzu!
18. What does the Power and Winter buttons do?
Power button does.
He checked with Isuzu engineers (so he told me): It does not increase power. It does not change timing. It does
 not affect the engine in any way. It does remap the auto transmission shift-up and shift-down points (but that
 doesn't count as changing "gearing" -- all the ratios remain the same, you'll just see shift points move to 
different rpms).
On the Power Drive, it delays upshifts and downshifts, essentially holds gears longer before shifting. It also 
increases the line pressure in the transmission. Increasing line pressure provides greater clamping ability of
 the clutch packs and converter clutch when applied. This mode is for towing or hauling. Constantly shifting under
 load and towing/hauling generates more heat as the friction materials slip as they engage under load. This mode
 helps to reduce the amount of heat generated which keeps the fluid alive and increases the life of the transmission.

"Winter" simply starts the vehicle in third gear. It's intended for very slick conditions. 
19.  How Performance Chips work?
20.  Transmission filter replacement and partial fluid swap?
Link to writeup
Link to Photo of the transmission filter (it is like a sponge)

So we get down there, look at it and determine what to do. * Support drivetrain on the t-case skid plate with jack. * Unbolt twisted, bent t-case/tranny crossmember. * Remove brake/fuel line heat shield protecting said lines from the crossmember. * Unbolt tranny support from crossmember and move crossmember out of the way. * Remove tranny support from the tranny. * Drain flid from tranny pan (2 plugs, one low, one high[allen head]). * Once fluid has drained, unbolt the pan from the tranny and set aside. * Unbolt filter from the tranny and discard. * Remove gasket material left on the tranny and pan. * Clean gasket mounting etc with a solvent on tranny and pan. * Remove magnet from bottom of pan and clean all metal dust remnants from magnet, and wipe out pan after all fluid has been drained.

[rant on]Since some BRAINIAC at GM/Isuzu designed the 4L30E WITHOUT a dipstick or any other way to fill the fluid, you get to take a bath in Mercron, no two ways around it... :mad: Remember the allen head plug I referenced, well that is the overflow aka FILL plug too!!! So, since the overflow hole parallel to the ground, how do you suppose you place fluid vertically into a pan that holds the fluid, maybe 3" below that hole? WTF, some people shouldn't live, or breed as the case might be.[/rant]

* Install new filter on the tranny, round hole down. * Fill up the pan with 6-7 pints of fluid (nearly to the overflow line. * With two people, lift up full pan to the tranny, and stick 2 bolts in opposing corner with each person (all 4 corners are bolted) * Complete the installation of the tranny pan, and reverse process for the crossmember, support, and jack.

What did the filter look like after 85K and yearly flushes on a 99?

It was full of contaminants... metal sludge (akin to a aluminum paste).
No chunks of metal, just sludge, again with the paste... thick and gooey, like aluminum colored mud.

I had trouble removing the two screws that mounted the black box below
the alarm box.  One of them was stuck tight.  I was able to remove the
black box from the metal bracket by releasing three clips; two on the
driver's side and one on the aft side.  After that it was fairly simple
to get the alarm box out.

A plunger style solder sucker was essential to removing the old relay
from the alarm board.



21.  Electrical problems

Couple of steps. 1. Clean the battery posts 2. clean the ground points to the body 3. Check The Ground At The Alternator Bracket

4. Have the battery load tested. 5. have the alt checked out

Issues with aftermarket alternator:

One more link on a possible electrical problems


Thanks... I searched and found a used alternator ($40 buck) plus $75.00 in labor to get it put on over the weekend. The flickering is gone for good I hope . Took the old one back to Oreilly's for a refund totaling $115.00. So i broke even there, I also am waiting to hear back form the district manager regarding my labor charge, he reimburst me the last time I took the first one that they sold me off. I spoke with the office manager this morning he said the alt. tested good so he could not approve the labor charge, but he will talk with the district manager when he stops by today. I told him that it may be testing good, but it's not good my truck. The voltage on my truck was eating that alt. alive....

22.  Opinions on Sea Foam

There is a ton of opinions on Sea Foam.  Many Isuzu owners like to use it a couple times a year to help clean up the piston rings.   But when the heck do you use it?  I personally use it 20 minutes before I change my oil (dump in 1/2 bottle take a 20 minute drive, drain oil asap).  PLEASE keep in-mind if you have a high mileage engine there is a remote possibility that the sea foam will loosen up a ton of crud that will plug some of the small oil pathways.  Please use it at your own risk.

Some more opinions:
Found the "SEA FOAM" info on this site. I had all but given up on the oil consumption problem on my 2000 Trooper 3.5. Dumped a bottle of the product in my crank case. Drove 100 miles and did my usual synthetic oil change with 10W 30. The oil when drained with the SEA FOAM additive looked and had the consistency of black gasoline. Four hundred miles later and the oil level has not dropped. By now I would be down 1/2 Qt. The Trooper runs smoother, quieter, and seems to have more power. I will follow up with more info at the 800 mile mark. I am impressed.  Regards, Jethro  
23.  Tips for removing the Alternator
take your passenger side wheel off, and take the small inner rubber liner out this will make getting to the alternator much easier. 
This was done on a truck with a 3" body lift.
24.  How to flush the radiator
1. Remove the radiator cap.
2. Loosen the drain cog/wing thing on the lower drivers side of the radiator.
3. Catch the fluid.
4. Dump in a bottle of flush stuff, then top of with your garden hose (or DI water).
5. Follow the directions on the flush bottle, which is something like run the truck for 15 minutes, with the heater on high blowing, 
turn off, drain and do it 2 more times.
6. Pull the reserve tank and empty that. The last time I did this I cleaned out the inside with a rag and soapy water 
since there was some black gunky build up in it.
7. reinstall tank.
8. Top off radiator with a 50-50 mix (mix with DI water). Add to reserve tank. Drive it a couple days then check your 
reserve tank and test your antifreeze concentration.

I do mine yearly. If you take it to a shop they will hook it up to a machine to flush out the entire system, but I 
think my yearly flush will work fine too. 


25.  4wd always on or doesn't work

Check your electric shift on the fly actuator. It's mounted on the drivers' side front axle tube. It's common for them to hold moisture & corrode or freeze up.

They key to 4wd is to use it at least once a month.  Turn it on, drive 50 feet turn it off.  This will help to keep the SOTF (shift on the fly) stuff lubed up.


Thanks to those of you who responded to my query about my 99 Trooper which wouldn't go into 4WD while the engine was running, but would occasionally come up in 4WD if the SOTF button was pushed before starting the truck. I'm going to go through how we found the problem because sure as heck someone else is going to run into this problem someday. The hints as to the existence of the SOTF vacuum switch mechanism and attendant website URLs proved invaluable. A friend with vast experience trouble-shooting such problems and I used his MightyVac to isolate the problem in one of the two vacuum switches on the SOTF assembly on the front axle. In short, the switch was not pulling enough air to coax the system into 4WD. We carefully tried to bring the switch back to spec (after pulling the assembly off the truck.) This requires first removing a small shield (Two 14mm bolts.) You then can use a 10mm socket to remove the plate holding the two vacuum switches (looks just like top picture in URL mentioned on PlanetIsuzu.) It took a while to trace the hoses attached to understand the logic of how the SOTF system works. We pulled the suspect switch off the plate (Phillips screw at back of plate.) Using the MightyVac and a couple wires, we used the truck's battery to actuate the solenoid with vacuum on it to see if it passed air properly. When it didn't we knew we were close to the bad part. Another check on that theory was to start the truck and use the MightyVac (a hand-held unit with a gauge on it and a handle that you squeeze to pull air out of hoses, bleed brake systems, etc. Gotta get one!) to put a vacuum on the hose that leads from the the suspect vacuum switch to the diaphram on the axle. Instant 4WD! Dealers being closed on Saturday, we tried a NAPA and another local auto store but no luck on the Denso part. Part #8-97101858-1 is what I read on the part. There's another number I took to be a manufacturer's number: 08480U-2201. It was bit smudgy but those are close. It took some judicious use of very small wire and eventually a good hosing with carb cleaner, but we got the part's logic to work with the good ol' MightyVac and the actuation of the switch via truck battery. Its resistance also measured at the noted 42 ohms (by, so we knew that it was ok electrically. We put it all back together and my TOD switch now works like a champ, every time. Of course, my dealer said this would be a $600 repair requiring replacement of the ECU, so you know I'm glad that with my friend Nick's help, we sorted this in a few hours in my driveway. The moral to this story, btw, is to exercise that TOD switch frequently to keep those solenoids from getting cruddy. I tend to only use 4WD when I 'need' it and thus it was the 4WD solenoid that crudded up on me.


26.  Isuzu Engine Rebuild Kits:

27.  I need a new Exhaust (muffler; catback):

Two options.  One is to buy a muffler and have it spliced in.  My suggestions:

BORLA Pro XS T-304 Stainless Muffler -O/C Necks #40357

                DYNOMAX SUPER TURBO

The second is a catback system:

            Calmini (seems like a lot of money for a couple of pipes and a cheep looking muffler)

            Borla use to make one for the Rodeo, so you might be able search or make some calls to see if anyone still has it on the shelf


28  Looking for new center caps for your Isuzu wheels?

If so check out:


29 How to Reset the O2 light on a 91-94

  since February 2004

Last updated: 07 Mar 2007