Anyone Seen a Smoking ECM Before?

[1987 GMC Jimmy]

This is a question about my car, but it's CCC so fairly similar to TBI and same setup as CA carbureted squares. I finally got a remanufactured ECM that held up, and it's been going good for a few thousand miles. Anyways, a torrential thunderstorm came the other night, and the next day I went to go get the car to run some errands. The sealer between the firewall and the evaporator/heater core/blower motor case was all cracked up, and I meant to fix it a couple months ago but didn't have time. Anyways, the rain seeped in, and ran down to where the computer is inside the passenger side kick panel and turned it into a fishbowl. I was so pissed because I finally got a good one. Anyways, I ordered a new one under warranty, and it came in. I popped the PROM in, hooked it up, and turned the car on. For about twenty seconds, the car ran great. Then my SES light started flickering, smoke started wofting out of the ECM, and the car started running bad again. I've had ECM's bad out of the box, but I've never seen them smoke before. The PROM did get wet, but I let it dry out, and the car did run fine for those few seconds. I figured if there was something wrong with the PROM, I'd just get a Code 51 and go from there. All I got was smoke and a complete failure of the ECM. At this point, I'm just assuming it was a crap reman, and I'll keep getting new ones until I'm back where I was before the thunderstorm. I got it all sealed up nice now, but too late for my old computer.

 

[HotRodPC]

You sure you don't have some wet wiring? Remember, water IS a conductor of electricity. If the plug even had water in it, that's the same as connecting all those pins together.

Just a tip for going forward, Remember what WD-40 is. W Water, D displacelent, 40 Recipe #40. Took them the 40th try to get it right. It's intent was NOT to be a lubricant like it is known for. Sooooo point is, next time you get in this type situation, spray your plugs and wiring in the general area that got wet with some WD-40.

 

[1987 GMC Jimmy]

You sure you don't have some wet wiring? Remember, water IS a conductor of electricity. If the plug even had water in it, that's the same as connecting all those pins together.

Just a tip for going forward, Remember what WD-40 is. W Water, D displacelent, 40 Recipe #40. Took them the 40th try to get it right. It's intent was NOT to be a lubricant like it is known for. Sooooo point is, next time you get in this type situation, spray your plugs and wiring in the general area that got wet with some WD-40.

I checked to see if the connector and wiring were wet, and the didn't appear to be, but I'll spray some WD40 in the connector and the wiring up until it exits into the engine bay. The water ran down the floor pan and pooled inside the ECM carrier/kick panel.

 

[Camar068]

Don't spray WD-40 near ignition parts while running! I did that to the durango looking for a vacuum leak. I'll be damn if it didn't light up.....on fire! Luckily I had an old water fire extinguisher close by.

lol I told my wife about it.....while laughing about 10 minutes later. She looked at me with this look like "and you know what the **** your doing....". Wish I had a picture, thats the only time I've ever got that look.

Sorry, anyway hope your figure it out.

 

[HotRodPC]

Don't spray WD-40 near ignition parts while running! I did that to the durango looking for a vacuum leak. I'll be damn if it didn't light up.....on fire! Luckily I had an old water fire extinguisher close by.

lol I told my wife about it.....while laughing about 10 minutes later. She looked at me with this look like "and you know what the **** your doing....". Wish I had a picture, thats the only time I've ever got that look.

Sorry, anyway hope your figure it out.

Good Point. It's not the WD-40 that will ignite its the aerosol gas that will. So if you must shoot it while running, which you shouldn't have to, be sure to be using a pump spray bottle.

Way back in the day, I made a **** ton of cash in So Cali everytime it rained real good. Back when most cars were points ignition systems, people would go through a big water puddle and get the points wet. I didn't want them knowing my secret so I had WD-40 in a squirt bottle. When the cars went through and died, I was there with a squirt bottle. Openend up the points adjustment window and put a couple squirts in the dizzy cap. Fords had the dizzy cap and just 2 clips holding the cap on. Pop the clips, 2 squirts and it fired up. $10 - $20 a car to get them started and on their way. Much cheaper than a tow truck. They were happy to pay.

 

[CorvairGeek]

I can't say I'm surprised, with the caliber of 'remanufactured' electronics, especially as obsolete as anything related to a vehicle with carburetion. They are so old now the electrolytic capacitors are due to fail too (probably all that is replaced in some remans).
I recently (within the last 2 years) tested an identical (including PROM) ECM from an '84 (Caprice) that I got from Barry's in Gulfport back in '95. It is an original Delco unit (not an aftermarket remanufactured) It still works! I had never even tested it before, just bought it back then because the price was so reasonable, and the GM core charge was still so high.

 

[1987 GMC Jimmy]

I can't say I'm surprised, with the caliber of 'remanufactured' electronics, especially as obsolete as anything related to a vehicle with carburetion. They are so old now the electrolytic capacitors are due to fail too (probably all that is replaced in some remans).
I recently (within the last 2 years) tested an identical (including PROM) ECM from an '84 (Caprice) that I got from Barry's in Gulfport back in '95. It is an original Delco unit (not an aftermarket remanufactured) It still works! I had never even tested it before, just bought it back then because the price was so reasonable, and the GM core charge was still so high.

I agree with you 100%. I've got a Caprice question for you, but I'll PM you in a few days when exams are over. Barry's U-Pull-It? I've talked to them on the phone before, but that's it. Are you from around here, or did they ship it to you? I got a good ECM this time, and it's running good. The rain is gone, too, finally. I went back today and saw that there was water again (however somewhat less) after a storm that was worse than the last one. I pulled the plastic cover that's under the dash on the passenger side and saw that some drips were coming from around the seal that's between that heater core/evaporator/blower motor case and the firewall. It's only in about four spots and it doesn't go the whole length of the seal. The car's my daily, and I don't want to go pulling all that. I'd rather just put some RTV and be done with it. I know that sounds like a bandaid solution, but if I do it correctly, I shouldn't have anymore problems. At least I don't think I should. No way in hell anyone makes that seal at this point in time. It looks like it's been leaking a long time because there's some rust flakes along the metal lip where the seal goes in one of the spots where it's leaking. The original computer was fried when I got it, too, so now I'm thinking it suffered the same fate as my last one.

 

[Rusty Nail]

Put it on a bag of rice, lol.

 

[HotRodPC]

Put it on a bag of rice, lol.

Yep, that fixes everything with electronics. Don't mind all the black stuff and all the melted solder, it'll be aight !!! Just dry it out in rice then plug it in.

 

[Rusty Nail]

Lol that's pritty funy.

OP did you use the rice thing?
Did you do the rice trick?
Uhh...pics!

 

[1987 GMC Jimmy]

I had it back together after the rice suggestion, but I considered it when I first found the PROM dripping water, and God forbid it happens again, the rice bag is the first place I'll go. I'll post up some pics tomorrow and show you guys what I'm talking about. Some of the pins on the ECM connector looked corroded, and I sprayed contact cleaner on them. The car runs even better than it did before. I wonder if those dirty electrical contacts were holding me back.

 

[Rusty Nail]

What happened to this dill?

 

[1987 GMC Jimmy]

Keeps messing up! Each one lasts longer than the previous one, but this makes three that I've gone through since the storm. This last one worked fine for a week, and I was very careful with it to minimize exposure to static electricity or anything that may even remotely hurt it. I don't know what the problem is. Last night I finished soldering up the TCC solenoid connector that had been chewed up by a rat, and repairing where the insulation had been gnawed on so nothing would short out. I ran it around, and about thirty minutes later, it started shuddering and pinging under load. Checked back today, and the ECM's burned (again). Here's a picture showing where the ECM is located and the hole inside the kick panel where it slides into.

 

[1987 GMC Jimmy]

Here's how it normally lives when it's not being a POS.

 

[CorvairGeek]

While I'm the first to be suspect of a remanufactured ECM, this is sounding a little suspicious.
Service Engine Soon light and any codes?
The correct procedure before replacing an ECM (according to the shop manual) would be to check each pin for abnormal connection to power or ground that could cause damage. This is easier said than done, and does require the schematic. It wouldn't rule out an intermittent short either. All I can suggest is a through inspection of the entire ECM harness, which isn't easy either.
Another thing to be aware of is that most consumer soldering irons / guns are not remotely ESD safe. They can develop damaging, high voltage (to sensitive electronics) at the tip. It would be best to unplug the ECM, Electronic Spark Control Module, etc., anytime a wiring repair is required.
As a last resort, if you can get a good enough look (I know it is not easy and may require some disassembly) at the ECM to see the area that is damaged, AND see enough of the traces to where they connect to the harness, you could give that area of the harness a very thorough inspection for any abnormality.