It all started last night when I decided to go outside and mist the plug wires to see if they were shorting. (I am in the process of trouble shooting a p0740 code) I saw now sparks so I decided to take it out for a spin. All was well for the first fifteen minutes or so then I decided to kick it down a notch. The engine started to miss a little so I backed off before it downshifted. I tried several more times with the same result and the SES light came on. I stopped, turned off the engine, started it up and there was no check engine light and it ran normally at WOT. Went home and pulled the codes. They were P0321 (ign problem, 18x interrupts lost signal). Also, P0361 which I think should be 1361 (elec spark timing, elec not toggling) And of course the P0740 but again, that is being addressed in another thread. So, this morning I decided to pull the coil packs and clean the plates beneath the ICM. (Now here comes the dumb part, laugh if you must cause I would do the same for you) I applied dielectric grease to all of the wrong places thinking that it was conductive. Since it didn't start I disassembled everything and cleaned it up with electric component cleaner. Still no crank. Went back in and cleaned everything, both sides of the plates, screws, whatever with a wire wheel and Dremel. reassembled. No crank. The pos battery cable was corroded down inside where the ends attach to the cable. Used a lot of cleaner and compressed air. So, now that you've caught your breath, any ideas on which way to approach this problem.

Oops, should read (Saw no sparks). Is this in rght location?

Problem is..you didn't list what the P0740 is.. didn't put this in the other thread... not to complain. but I'm leaving this thread to go find the original issue with the car in case it'* relevant. See ya in a few

Back. P0740 is a TCC clutch failure.

Probably not relevent.

Being that you did the removal and install only w/o actually disturbing much..it'* odd. Although the codes you mention would point us to the crank sensor or wiring leading from the ICM to the crank sensor. A crank sensor can cause stalling and no starts.

Only two things you could have potentially done in gooping and degooping is put wires on in the wrong order or leave the ICM connector (gray and in front) unhooked. Leaving the connector unhooked is a sure way to have no start. And the only issue I have with that is your title is .. "won't turn over" which means the starter is not working and the engine does not turn over or try to start.

More info on those last to thoughts would be great. If it does turn over and not start, I'd aim for ICM connector/crank sensor. If it doesn't turn over, it'* be checking the starter and it'* connections to the battery.

OK, you say the car does not crank, so I assume it'* not turning over. Is there a click at the starter? If you try to jump the car does it crank? The answer to this will determine what to clean. No crank with jump, clean battery cables opposite the battery. Crank with jump, clean at battery post. There is also a possibitly the battery cable is bad.

Here are two tests that might help.
https://www.gmforum.com/t279492/
https://www.gmforum.com/t279494/

Thanks for the quick reply Bill. When I turn the key there is no response from the engine. I suspect that I am overlooking a connection. I did reconnect the ICM but I'm going to go over it all again today. I also have a 94 Park Avenue so I can compare all of the connections.

If the engine is not cranking it'* not the ICM. Check the connection at the starter. Try the tests I listed.

There should be one connection to the negative terminal of the battery and two at the postive terminal. There have been a couple times where the second positive tried to fall down and hide on me.

Hopefully it'* an easy one. I'd suspect either that cable or a starter. You can check the starter after the cable by having someone turn and hold the key while you hit the starter with a hammer etc... if the car starts..it'* a bad starter.

Another good suggestion Bill. Leave the ICM alone now. That'* not the problem.

Ya know...talking about cables reminded me of another thing.

Early on in this body style etc..call it around 1988 the ICM and coils got their ground from the plate and engine. Around 96ish, GM added a ground to the ICM connector and the ICM no longer requires a good connection to the engine for a ground.

Sooo cleaning the plate after 96 is nice, but not actually necessary.

Danthurs, I didn't see your post when I replied this morning but you guys were right on the money. I did try to jump it last night but no go so yes it was the connection opposite the battery.Thanks for all of the excellent suggestions. It was the negative battery cable that connects underneath the plate. Last night when I should have been sleeping it occurred to me that I had seen a large cable grounded beneath the ICM plate so that is the first thing that I checked this morning. It had fallen down into the engine compartment and I assumed incorrectly that it was connected further down on the engine. I reattached it and it started right up. Thanks again guys.

Older Bonnies, nice to have; troubles, goes with the terrirtory; this club forum, Priceless