A 30-year-old Engine Control Module -- another addition to the "Trooper Saga"

[BonzaiDuck]

I have "symptoms". They are occasional symptoms -- so far without repeat events.

About a month ago, the ABS (anti-lock braking system) idiot light turns on after starting the car. There's nothing wrong with the brakes, and nothing wrong with the ABS. Turning off the car and then starting it again, this LED irregularity does not occur.

About two weeks later, I start the car, and the Transmission Warning LED is flashing. Shop manual makes it clear -- it's not the transmission; it is the initialization of some sort of scratchpad RAM associated with transmission data. Turn the car off, start it again -- no problem.

One of the door locks does not respond to the main door-lock switch on the driver's side of the car (or any side, for that matter).

According to a blog at FLAGSHIP ONE , these items are all within a category of symptoms suggesting a deteriorating ECM.

The SUV still runs great. But I need to prepare for an ECM replacement. There are plenty of them available for my year, model, trim, SOHC engine and auto-transmission at EBay.

Fine and good. I already bought one of them, advancing $80 for the item on EBay. I will consult with my repair-shop owner, who often remarks "we service several of those old Troopers here". They have a mechanic -- I'm sorry -- a technician -- whose Isuzu experience goes way back to a dealership in the 1990s.

Only question is -- "When should I arrange to make the replacement?"

Comments welcome.

Please note. I have an HVAC-plumbing repair guy who has been visiting me for ten years or more, who last week showed me pictures and videos (videos!) of his three four-wheel-drive rides. He has THREE (3) 1988 Troopers, and he has replaced the ECM on his favorite. We're not going to throw the vehicle away just because it needs a new or used-but-functional ECM.

Of course, when my real-estate property sells in another state this summer and cashes out, I have my mind set on a four-year-old pre-owned low-mileage RAV4 Hybrid. I think that's probably a good replacement for the old Trooper and its 76-year-old owner. That's the one . . . .

When I say "replacement", I mean a "main-ride replacement". As long as the Trooper runs, as long as it can be repaired and maintained -- I'll keep it.

 

[deadlyapp]

Whenever you want to. ECU replacement should take less than an hour, usually just a quick removal of a bit of interior and then undoing some plugs.

 

[Lost_in_the_HTTP]

'95 Taurus Wagon, all sorts of weird problems; CEL on, loss of power, excess exhaust smoke, massive rate of fuel burn and so on. But all very intermittent. Might run for weeks with no issue. Then might not run for ten minutes without trouble. Never really stalled, just ran like crap. Into two shops, they couldn't fix it because it acted normal. Never acted up for them, so no diagnosis.

Finally gave it a go, ordered a computer from Advance Auto for about $80 and change. Ten minute changeout. No problem since ... 7 or 8 years. Runs like a top.

 

[BonzaiDuck]

Hey! For both of you guys -- Lost-In-HTTP and deadlyapp -- my deepest appreciation.

You've raised my confidence about this. I know my trusted technicians will have to pull back either part of the center console or the dashboard, and it may wreak havoc with wiring I'd added for my USB and MP3 player. But it will probably be a risk worth taking, or even an inconvenient setback worth fixing up after they're done. I DID leave enough slack in the wiring, or so I tried.

I just spoke to my cousin the former career car mechanic. He'd had the same trouble with his Tacoma pickup truck, and ran all over LA and jump through hoops to get his ECM replacement. Somehow, with the spare and used parts through EBay available, I don't think I'm going to have a problem. An ECM with the proper Isuzu part number will arrive on my doorstep by early next week.

The only question might be "When do I really need to replace the ECM?" and I think deadlyapp is confirming my own sense of it. If I had that 95 Taurus wagon, I'd be running to the repair shop to plan and execute the changeout no later than tomorrow. But -- I'm glad the Taurus is now a tip-top standup ride for the ECM surgical operation.

So Wednesday, I'll see what Michael the repair shop owner says and recommends. But I'm encouraged. Some people throw away their cars because their ECM or ECU went south. I think we're all a bit smarter than that.

 

[Lost_in_the_HTTP]

Mine's weird. There is a connector in the engine bay at the firewall that has to be unplugged, but the computer is mounted in behind the glove box, sort of through the firewall. Remove the glove box and the unit pulls through towards the passenger seat. No real disassembly involved.

 

[deadlyapp]

Hey! For both of you guys -- Lost-In-HTTP and deadlyapp -- my deepest appreciation.

You've raised my confidence about this. I know my trusted technicians will have to pull back either part of the center console or the dashboard, and it may wreak havoc with wiring I'd added for my USB and MP3 player. But it will probably be a risk worth taking, or even an inconvenient setback worth fixing up after they're done. I DID leave enough slack in the wiring, or so I tried.

I just spoke to my cousin the former career car mechanic. He'd had the same trouble with his Tacoma pickup truck, and ran all over LA and jump through hoops to get his ECM replacement. Somehow, with the spare and used parts through EBay available, I don't think I'm going to have a problem. An ECM with the proper Isuzu part number will arrive on my doorstep by early next week.

The only question might be "When do I really need to replace the ECM?" and I think deadlyapp is confirming my own sense of it. If I had that 95 Taurus wagon, I'd be running to the repair shop to plan and execute the changeout no later than tomorrow. But -- I'm glad the Taurus is now a tip-top standup ride for the ECM surgical operation.

So Wednesday, I'll see what Michael the repair shop owner says and recommends. But I'm encouraged. Some people throw away their cars because their ECM or ECU went south. I think we're all a bit smarter than that.

The only thing I'll say is that with those older vehicles and ECMs, they often have bad electrical components that can cause all sorts of issues. I wouldn't always trust a used unit to solve your issue.

I think your year is probably a hybrid, not OBDI, not quite OBDII, but it may just barely scrape into OBDII.

 

[Torn Mind]

Is the ground cable to the battery or anywhere else is unblemished condition?

I had a issue where the car, a Toyota Matrix(not exactly a complicated car compared to other makes) would automatically lock itself. The battery used was a Toyota Tru-2, a battery designed to fail in a manner that screws up the posts and the connector to the post. Changed the cable, haven't had the issue reappear...ever. I think I have an old thread in this forum talking about bad grounds.

 

[BonzaiDuck]

Is the ground cable to the battery or anywhere else is unblemished condition?

I had a issue where the car, a Toyota Matrix(not exactly a complicated car compared to other makes) would automatically lock itself. The battery used was a Toyota Tru-2, a battery designed to fail in a manner that screws up the posts and the connector to the post. Changed the cable, haven't had the issue reappear...ever. I think I have an old thread in this forum talking about bad grounds.

That sounds unusually peculiar -- a matter of a cable and battery causing more complex -- or seemingly -- events.

Just looking through my posts here and on another thread about understanding hybrid gas mileage, I've told the entire story now.

So I've got the spare junkyard ECM part # *********790 on my desk. We can swap it out, but according to my repair-shop-owner, no real indication that the old one is starting to go south. He's just offering to do the work if it will make me feel better. I have a minor oil leak that appears as mere drops on the drop pan over a week's time, and it takes a little while to start the car when it's been sitting warm after driven. I think that's where I'll put my money this summer -- these latter two problems.

Otherwise, it's been a standup ride every time I take it out of the garage in recent days and weeks. And now, after pulling a tendon in my calf yesterday during my senior-citizen health-walk, I'm going back on the trail and see if I can rack up two more miles today and work out the stiffness from yesterday's minor sprain. The weather is still just perfect.

 

[RLGL]

Chase the harness connections, looking for loose connections or corrosion. Pay attention to the harness, looking for the tracks that corroded copper leaves behind.

 

[Lost_in_the_HTTP]

"That sounds unusually peculiar -- a matter of a cable and battery causing more complex -- or seemingly -- events."


Yes, a bad ground can cause all sorts of weird issues. Power needs a clean flow for each circuit. Any interruption can cause problems and a bad connection that causes a high resistance or low voltage can add to it all. Computer needs 12 volts, but if it's only getting 8, who knows what it might do (think a dim bulb in a headlight or turn signal).

 

[BonzaiDuck]

My last post included a remark about seeing my repair-shop owner on Wednesday.

Again, my repair shop guy doesn't think I have a dying ECM. He says a very small number of all the cars coming through his shop ever required the computer swapout.

The glitches I experienced occurred when I was fiddling with the ignition key (on and off again and then on) when the car was warm and took longer to start. I have since confirmed that this starting delay does not yet appear to be a real difficulty. I let it crank a little bit, then tap the accelerator half-way, and it starts without dying.

We're going to take a different approach, as opposed to swapping out an ECM which is not likely gone bad. They can troubleshoot the delayed hot starting problem, and it may be a defective fuel pressure regulator valve on the driver side injection rail. If they confirm that, I will pay to swap in a new $50 regulator/valve. If they need to partially remove the intake manifold to swap the part, it will mean higher labor charges, but I intend to have it done.

At the moment, it still appears possible that my Blue Devil oil treatment may entirely stifle the tiny oil leak, but if the leak continues, I will pay to have them fix it. Even so, it isn't costing me any noticeable oil loss. It is a very tiny bit of oil -- paper shop-towel smudges after a week's time.

All things considered, I have the new ECM; it's exactly the right part number. I'm going to set it aside in case we really have an ECM die in the future. Even so, the swap out is -- as you gents had noted -- an easy 20 minutes of work.

This week's driving with the old Trooper has been absolutely stellar. I just wish the city-driving gas mileage was a bit better, but everything with that is otherwise "factory spec EPA mileage".

I had posted before recently in another thread -- I have a 95 Nissan pickup truck all in good order, and the Trooper. I am planning to purchase a 4-year-old low-miles pre-owned Toyota RAV4 in early spring next year. One of the two old vehicles must eventually "go". Otherwise, I'll be playing round-robin with the visitor parking spaces here at the condo development, because my garage only holds two vehicles at a time and the association has a rule about using those visitor spaces for "spillover".