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Discussion Starter · #1 ·
Greetings all, my first post. An Isuzu Trooper 2002 with TOD . One owner. The last Trooper sold in Jacksonvill FL.
Stopped like it ran out of gas in light rain. Cranks fine. Towed to shop who can only find three O2 sensors as the problem. Next day, started and ran. They want me to drive it home.
They are afraid to touch the ECM because wires may be brittle. Will try to drive it home tomorrow.
History...Changed oil religiously. Transmission filter once. Serpentine belt once. New starter once. Never did plugs or fuel filter.
Mouse ate some very small wires years ago near firewall, near main brake cylinder but no change in how vehicle ran. Only an O2 code a parts shop told me to ignore. Never driven off road.
Sometimes when it has rained during the night, it starts ok but runs a tiny bit rough for 10 minutes.
Bad ECM? Bad wires or dirty contacts? Do I need a code scanner...which? Can I get a ECM eBay or scrap yard without reprogramming?
I'm thinking change fuel filter, check rail pressure...maybe it's just a bad fuel pump.
Thank you in advance for the collective wisdom.
Mark the manatee.
 

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Fuel Pressure is not monitored by the OBDII system so a fuel delivery problem would not create a diagnostic trouble code. I recommend you buy a fuel pressure gauge to check the fuel pressure at the test port. You should also consider buying a scan tool that can monitor live data so you can retrieve engine sensor data monitored by the ODB II system to help in troubleshooting.
Btw, a 02 (96-02) Trooper has a Powertrain Control Module (PCM) as opposed to an Engine Control Module (ECM). The PCM controls the engine and 4L30e transmission. You can swap the PCM in your truck with one from a 00-02 Trooper with 4L30e transmission. Additionally, TOD is not part of the transmission, there is a separate TOD "computer".
 

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Discussion Starter · #3 ·
Took it home today. Nice dry sunny day. It ran fine, shifted fine, started several times hot and cold fine. Went to a parts store and they confirmed the only codes are O2 which is what the shop found. Given its running, do I need to buy a scanner...if so, what's the best for $100.
I will change the fuel filter and air filter. I'll buy a fuel pressure gauge and I know where to connect it. One mechanic recommended using electrical connector cleaner then dialectic grease on the PCM connectors. I can only find one type of cleaner. Any particular brand works well? The only markings on the computer are: Delphi 1 and J 1 Blue.
I want to be sure I understand. A computer from a 2002 with the same transmission is a swap out part. Correct? Anybody have these rebuilt or new that you recommend. Also the shop wrote they were hesitant to remove the connectors because the wires were old and brittle. I m a boatbuilder and do a lot of marine wires so I understand they didn't want to break something which might not be bad to begin with...so I'm thinking #1, fuel filter, air filter, test rail fuel pressure. Clean the computer connectors and grease them.
Drain the tank for crud ...?...In yachts we see this issue all the time. Is there a drain? Any suggestions?
The trooper is old and not much use. 101,000 miles since I bought it new. Never any problems till now. We live on a boat and I'm not a daily driver. I'd like to keep it going. OH, I've never changed the spark plugs or cleaned the throttle body or any other engine parts except the serpentine belt. Did the brakes completely and the transmission filter once. I'm not a good owner but I had to build a boat too. Any suggestions deeply appreciated. Sincere thanks for the incredibly generous help.
Mark
 

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repair any rodent chewed wires first and foremost. then clear the codes, go for a drive and see if it sets any codes. sounds like a wet weather connection issue, not the actual pcm itself...petroleum jelly works just as good as dielectric grease.

the shop that mentioned pcm, and brittle wires, sounds like they are scared to actually diagnose / repair an isuzu. when the shop has no clue how to diagnose, they automatically blame the pcm / ecm. seen that many times.

as for it dying, you need air, fuel, spark. one of those goes missing when its wet out, and it wont run. spark plugs dont perform well when its wet out. makes them harder to fire. air is air, when it dies, pull the air filter and see if it re-starts..that one is easy.

sounds like you are going to do a fuel pressure test. that should rule out any fuel related issues...as long as it isnt bad wiring to the pump, making it a intermittent fuel issue ( again, when its wet out )
 

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The PCM is a swap out part but it seldom fails so it is not likely you would need to replace the PCM. A replacement for your truck has to come from a 00-02 Trooper with 4L30e.

For the engine to just stop running and then restart after a few hours suggests a fuel delivery problem. In some rare instances the engine shuts down on fuel exhaustion because the gas tank vent valve is plugged with debris so a vacuum is created in the tank as fuel is removed. When the vacuum gets high enough the fuel pump can't pump fuel. If the engine shuts off again while your driving loosen the gas cap and see if it will restart. If I recall correctly, a 02 Trooper gas tank has a drain valve. I don't believe you can buy a useful live data scan tool for 100 bucks, maybe a code reader but not a scan tool. I would defer cleaning the PCM contacts for now because the the problem does not seem to be PCM related. Recommend you install a new set of single platinum spark plugs. Fram/Autolite AP3924 spark plugs are inexpensive and work well with the installed Ion Sensing Ignition System in your truck.

If you have O2 sensor codes set what are the DTC numbers?
 

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Discussion Starter · #6 ·
I changed the fuel filter, the air filter and tested the fuel rail pressure. When running, it’s about 35 psi. Harbor freight gauge, so I doubt that it’s accurate. I’m ordering the spark plugs today.
The car starts right up and feels like new.
I feel horrible I didnt pay more attention to it. I love this old school ride.
Looks like it’s not the computer after all. I have an apple iPad , no computer because we live on a boat. Is there any shop manual you guys recommend?
I’m planning on changing the transmission filter again. I’ve done this once and have an electric pump for the job. I put in synthetic last time. It shifts fine. I saw a guy add another cooler on his Isuzu named sreck ? Is this worth doing. Is there a way to add a trans temp gauge ?.Good idea?
The check TOD light is on. What could it be?
The check Engine light is on too.
Again Sincere thanks for the advice. Really appreciated!!!
spark plugs are next.
Happy trails to you.
Mark the manatee (that’s how slow I drive)
 

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Discussion Starter · #7 ·
I changed the fuel filter, the air filter and tested the fuel rail pressure. When running, it’s about 35 psi. Harbor freight gauge, so I doubt that it’s accurate. I’m ordering the spark plugs today.
The car starts right up and feels like new.
I feel horrible I didnt pay more attention to it. I love this old school ride.
Looks like it’s not the computer after all. I have an apple iPad , no computer because we live on a boat. Is there any shop manual you guys recommend?
I’m planning on changing the transmission filter again. I’ve done this once and have an electric pump for the job. I put in synthetic last time. It shifts fine. I saw a guy add another cooler on his Isuzu named sreck ? Is this worth doing. Is there a way to add a trans temp gauge ?.Good idea?
The check TOD light is on. What could it be?
The check Engine light is on too.
Again Sincere thanks for the advice. Really appreciated!!!
spark plugs are next.
Happy trails to you.
Mark the manatee (that’s how slow I drive)
I think I could use some kind of code reader ...any recommendations under $100.
I don’t have a computer, just an iPad. How can I get a factory service manual?
Is there anything else I can do to save my transmission. Keep changing the filter and fluid?
I don’t tow or go off-road, would an extra cooler help. I’m in South Georgia.
I’ve ordered new plugs and boots.
Thanks for the advice, Mark who drives like a manatee swims.
 
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