I have a 1989 GMC suburban 1500. Last friday I turned out into traffic and it just died, as if I just turned off the key.
It would not restart. Had it towed to local shop. They told me the wire connecting the computer to the fuse box had a short in it and needed to be replaced, so I told them to do so. They replaced the wire and everything was fine, the truck would now run as normal.
The following week on thursday (Thanksgiving) I was on my way to a thanksgiving dinner at relitaves when once again I turned onto their road and the truck died as if I just turned off the key. I checked the 10 amp fuse to the EMCI, It was blown. I replaced the fuse and as soon as I pushed the fuse into the slot it sparked and burned out. I got another 10 amp fuse and same thing, the fuse for the EMCI kept blowing every time I would try to replace it. So my problem is something else??? Maybe the computer itself???
Maybe they didn’t replace the right section of wire.
Unplug the computer and see if the fuse still blows.
If you want to try and find the trouble yourself you can replace the fuse with a brake light in series with the fuse connection. The lamp will limit the current to the short to a safe limit. Then start disconnecting suspected trouble areas like the ECU and see if the light goes out or goes dim. When it does it means you have cleared the path to the short and the connection that was removed needs to be checked out for the short problem.
I had the suburban towed to the shop. For the second time and the next mourning they put in a fuse, and it did not blow, the suburban started right up as if nothing was wrong. The shop told me they had had an incident a few months ago with a suburban that kept blowing the computer fuses and would not run and they finally replaced the ignition control module and that fixed the problem, so thats what I told them to replace, it’s been two days now and suburban still running, but I’m still having cautious distrust that the truck will die on me, as the last time it worked for a week before it went out again.
I know throwing parts at it is expensive, but when no one has a clue to what’s going wrong it’s the only thing you can do at this point, to go with others experiences and decide from that.
This is my only vehicle, and I can’t afford to buy a new vehicle, but I have been able to keep this suburban alive so far, I need this vehicle to keep employed.
I also read about something called a crank shaft position sensor doing the same thing of blowing the computer ECMI fuse, but I don’t even know if this 1989 GMC Suburban has one, as every parts search I made came up with “We don’t have a crank shaft position sensor for 1989 GMC 5.7L Suburban”, so I don’t think this truck has one of those???
Our technology just sent a space probe to frickin mars, but no one has a clue what’s wrong with my 1989 GMC Suburban 5.7L, now that’s funny, I mean real funny.
They did unplug the computer and the fuse still blew out “circuitsmith”.
“Cougar”, what your suggesting is way past me, I’m a artist/illustrator and though I could draw the broblem, no way could I attempt to track it down mechanically, not my skill-set.
Jim, since you are not sure how to work with my previous suggestion I think your next best thing to do is purchase a wiring diagram for the vehicle to help guide you to the trouble. Your best resource is a factory service manual for the wiring. It will show you what is tied to the fuse that is blowing out and where things like connections are physically located on the vehicle making your job easier. The fuse may also supply power to the O2 sensor heats or other engine related devices so I would check those areas for a problem. Possibly a burned wire on the exhaust manifold or pinched wire possibly to ground.
My other suggestion was just taking the two wires from a old brake light and tying the wires to the two fuse wire connections. So instead of a fuse for the power to run through, it now has to pass through the brake light. The light now basically becomes the load for that circuit since the other end of the wiring is shorted to ground. The light turns on until you find the area that has the connection to ground and disconnect it. Then the light will turn off and you will know you have found the path the trrouble is connected to.
I did order a factory service manual. So far the truck is running after they replaced the ignition control module, so far so good unless that wasn’t the problem. But that 02 sensor went out before and they replace it with a new one, so I will check that again to make sure it’s still working.
Thanks for the tips ‘COUGAR’, ha, times like this I wish I had a guy like you living next door, ha!
Take care, and when I have checked everything that could have caused the problem I will get back to ya with the results. Gonna call those car talk guys this saturday to see if they have some other tips!