Where is my ECM and how do I get to it?

I have a 1986 S15 Jimmy 4X4 and it quit running. First I noticed the voltmeter was down about 2 volts from it's normal. Then it quit with the check engine light on. I got it started (with the check engine light on) and was able to get it to run about 5 miles to home. It did not run well. Cutting in and out in first gear and just herky-jerky all the way. Now it will not start. It does run if fuel is put in the throttle body. When I jumper the test pin on the test connector to ground, the check engine light goes out and the shift light goes on. I also hear a relay closing when I attach the jumper.

I am trying to get to the ECM. I can find the cable running to it under the carpet on the passenger floor, but I can't find a way to get to it. The GM service manual is really careful to avoid any helpful information.


Thanks for checking

Jim

What is the code when you jump the diagnostic port under the dash, it is premature to worry about getting to the pcm, if it runs with starting fluid in the tb, then you have no injector pulse or no fuel pressure. You should get flashes from the CEL when jumping see this link. I guessed that you have a 2.8, always post the engine size. .http://www.troublecodes.net/GM/

Sorry for forgetting the engine size. Since I cannot get any response from the diagnostic port other than the relay clicking and the upshift light coming on, I did not think the engine size was significant. I concluded that there was a connection problem with the ECM. I wanted to cycle the connectors.

I have a complete copy of the GM service manual for the 1986 Jimmy. It has complete listings of all the service codes from the ECM and full trouble shooting charts. Last year when I was checking things, I just got a code 12 and other codes when grounding the port. There was no other stuff acting up. Are you suggesting that I should expect a code from the ECM even though it is lighting the upshift light and closing a relay instead of responding with service codes?

I have installed a booster fuel pump and run it while cranking, it does not help.

Ok we still don't know if this a pfi 2.8 or a TBI 4 cyl. Anyway, at least 12 should appear when grounding the aldl, if not there is something going on with the pcm, again injector pulse or not is the key here as well as is the fp running when it won't start, also fuel pressure present.

OK. I gave up too quickly on the ALCL code output.

But it only reports code 12.

Translating the VIN using the service manual shows:
Code R, Producer Chevrolet, Type 2.8L TBI, RPO LL2

I'll go back to the diagnostic charts and see where I get. Thanks

It runs! Thanks for keeping me away from the ECM.

Originally, the problem must have been a dead fuel pump, but the booster was capable of correcting that except for a pinched inlet hose. It wasn't pinched when tested into a container on the floor, just when the outlet was connected to the TB.

With the booster in place I can get the fuel out of the tank to ease the fuel pump replacement job.

Thanks again
Jim