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I was looking at a different thread and learned that when the key is turned on the check engine light should come on showing that the computer is powered up. I went out a checked that and saw that my CEL doesn't come on when I turn the key on. I wonder what's gonna happen next.
It's probably been that way you're just noticing now that you're looking....maybe its related to your main problem and will help you get it resolved, you sure seem close
the check engine light comes on for about 2-3 sec when i first turn the key on in my 91 but my 87 had a similar problem with the guy i got it from and he ended up needing a whole new computer but im just jumping in idk if that is even relevant right now
. Whatever is going on with that thing the CEL turns on for about a second at key up ('86 ECM in the repinned '90 harness, still running DIS) but I'm not sure that circuit is correct as at times it comes on dim while driving when there aren't any codes or anything...No, it hasn't been that way for very long, it was coming on and the truck would start and run as long as I had the jumper wire in place. It hasn't come on since I tried the reman. ECM. I returned the ECM and put my computer back in, no spark since then.
I have checked and rechecked everything to the point that it's no use to keep checking. I replaced the fuel pump relay but it made no difference, this no fire problem has only been since I swapped computers. The truck would start and run with a jumper wire in place but it would not start with the reman. ECM and it hasn't started since. I put my ECM back in but made no difference it still won't fire.I just checked on my '90, it needed attention anyway... apparently it still runs so that's a bonus
At the EEC relay I probed the wire from the ignition switch, #2 and it showed 12.19 volts, I then probed wire #3 output voltage to the computer and got 11.31 volts. I have two red wires going into the computer I probed each one with the key on and they both showed 11.31 volts
Today I did some more testing and found...When I ground #1 wire on the fuel pump relay with a jumper wire to the battery-, the check engine light comes on, the fuel pump runs and the truck will start and run. I checked the white w/blk. wire going from the ign. switch to the EEC and there is power at the EEC. Does this mean that the EEC is not grounding #1 as it should be or does it mean I need to check something else?
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