: 93 Eldo intermittent no spark,no start



Aaron J Williams
11-29-05, 07:43 PM
Ok, so here's my tale of woe. Eldo died in the driveway a month ago with no warning and no codes.Pushed it in the shop and checked for spark-no spark. First order of business was to check for power at the ICM which I had . then I checked for ground which I also had. Then the alldata says to start the car and check the frequency of the 4X reference signal from the ICM which I couldn't do since it would not start. So I read further down and the solutions were to replace the ECM or replace the ICM . Since the ECM was only $90 and the ICM was $299 I replaced the ECM and updated the PROM to the latest version while I was at it. Then the car starts and runs fine. Took it out for a test drive and it dies 3 miles from my shop,NUTS! Tow it back and no spark again. Checked for power and ground again and had both but it flipped a code for ECM ground circuit fault which means that the ECM case was touching the body . So I pulled it out again and checked it and all the connectors going to it and even removed the PROM to check for bent pins to no avail. Now its time for a new ICM which I bought from GM because they had a TSB about radio noise and the 93-94 N* which would be solved with the updated ICM and bracket. Fine, if i'm going to buy the part anyway i'll buy the updated one. Imagine my surprise when the car didn't start with the new ICM. Now i'm getting ticked off so I ohmed out every wire from the ICM to the ECM and also checked each one for continuity to ground and power but found no faults. No cam or crank sensor codes were present but I checked the sensors frequency anyway and found they were all putting out a signal. So now i'm stumped and afraid i'll never hear my baby run again.I searched the forum with no luck and re-read the diagnostic procedures on alldata looking for a clue. Alldata said to look for 11 volts at the ICM but I had used my test light instead of my DVOM . I checked it with the DVOM and had 7.2 volts :banghead: After running a jumper wire from the battery and verifying 11 volts the car started right up. Pulled the jumper and it died.The problem was a loose terminal at the underhood fusebox.Once I cleaned it and bent the terminal tighter,everything worked fine. Sometimes its the basic things we overlook that solve the problem. Thank god it was my own car and not a customer car or I would have really felt bad throwing all those spendy parts at it. On the bright side, the car gets 2.5 MPG better than it did and my cooling fan system is now functioning the way it should,and no more AM radio noise!
:alchi:

thu
11-29-05, 11:13 PM
Very happy to hear you won this battle and your baby is back on the road in even better shape than before the problems started! Congrats!

Spending $400 is less than what you would have paid elsewhere plus, you are now very familiar with the ignition system, which is always a good thing.

Eldyfig
11-30-05, 12:16 AM
Which terminal was loose and how do you think it happened?

I will keep that updated ICM in mind if I ever have to replace mine on my 94.

zonie77
11-30-05, 12:18 AM
You're good!

I had a couple of strange problems that would've cost an arm & leg to have fixed. Even with the manual and reasonable diagnostics they were bears. I was glad I wasn't charging someone!

Aaron J Williams
11-30-05, 09:43 AM
The Technical Service Bulletin # for the radio noise update is 479601 and it's dated March. 1994. The terminal that was loose was the one hooked to the dark blue wire feeding power to the ICM. From the looks of some of the other work I have fixed on this car done by hack mechanics i'd guess that they needed power for an alarm system or something and they crammed a wire down in the terminal and then crammed the fuse down along side of it thus stretching the connector.

Eldyfig
11-30-05, 01:03 PM
Good find, thanks for the info.