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hello Gumby22, had a guy recommended by a friend put it on some of his diagnostic machines, as best we can tell the icm, brand new remember, burnt up, just spark side not fuel side. He spent another hour trying to find out why. Only thing he found was the after market tach I installed, I used the white wire from the computer to the icm. Now that’s the way the instructions said to do it, but it makes sense, especially since I found out there is a extra connector down in their to add a tach, I had seen it but never knew what it was. Thing is it’s been on there for a year. Lol. Maybe a bumpy road started it down the wrong path. Ironic I have a nice new ac delco icm sitting on my bench. Lol
i have a feeling it may reoccur one day but hopefully not. Appreciate all the help!
I gotta start another thread soon, I got a “clunk” under minor acceleration. I’ve taken everything apart and it’s good. Yet there is still a clunk.
Originally Posted by Gumby22
Are you checking for spark at the coil or from one of the plug wires off the cap? If the new distributor cap or rotor is bad for some reason, maybe spark is present but not making it past the cap. Just a thought.
I’m still trying to find more specific info on the signals between the ICM and ECM, but have you tried checking for diagnostic codes? Even if the codes stored don’t seem to have anything to do with spark control, sometimes they can help point in the right direction.
The OBD pinout is below - all you have to do is jumper pin A to pin B (or pin B to ground if the jumper doesn’t seem to work) and then turn the key on, engine off, and count the blinks of the SES light. Each code will repeat 3 times before the next code is displayed, and code 12 (system pass) will be the first code regardless of any other stored codes.
This sequence reads out code 12 once the key is on. After the 3rd display, any other stored codes will blink out. They will all be 2 digits - even if you don’t know the definitions, post them and I can look them up.
I’ve seen a few aftermarket gauges that have shorted out before, so I don’t find it completely surprising.
The spare connector at the distributor could certainly be used for installing a tach, but its primary purpose was for technicians to have a quick way to hook up a “toolbox tach” to monitor/verify engine RPM while troubleshooting.
Fixed but nothing learned
