chopperclay

Yes, I did disconnect ECM connector A when checking Voltage... My friend recommended the coil swap but I was wondering myself as to why and how this could affect the problem.. Plus it is a new Coil...

c4_4ya

What have you done recently to the car before this started? Have you specifically done any work under the dash? I replaced the speedo in my 92 and when I put it all back together, I had a CCM data wire pinched between the steering column and bracket with voltage to ground. Drove me crazy for weeks.

chopperclay

Interesting point, I had the steering wheel off some time back because of a blinker problem. I planned on replacing the Blinker switch but found the problem was actually a broken part/linkage preventing the blinker lever from actuating the switch. This could be a possibility and I am running out of ideas as to any other causes.. Thank You!

chopperclay

I have also noticed difficulty turning the key switch to the off position. I'm guessing that maybe this could be a wire interfering with the mechanism....Maybe????

desertmike1

Did the car run normal before this work was done..

chopperclay

Yes, Its always been a strong running car, the only problem I've had has been restarting the engine once it warms up. I think I caused this by Gunking/washing the engine (like a fool) At first it developed a miss which later turned into difficulty starting after it warmed up. The miss went away. I assumed the Optispark was the problem, replaced that and ran fine but still would not restart when warm. replaced Coil, ICM now it does not want to start even cold. I did get it started once and ran fine for 5 minutes then crapped out again.

toptechx6

What was the voltage reading on circuit 423? Assuming the test procedure was followed correctly, I would be surprised if the steering column problems are relevant to the issue since circuit 423 does not run inside the cabin.
My suggestion would be to run the voltage check again while a helper flexes the harness between the ICM and ECM, if you get a change in the reading the portion of the harness being moved should be inspected carefully for damaged wiring. good luck.

chopperclay

I think we were getting around 12 volts. My buddy was helping and I wa sin the car, I'll have to ask. This makes sense.

toptechx6

When searching for a circuit shorted to voltage, I would expect to see battery voltage (12 volts) or 5 volts which is the supply voltage sent to sensors by the ECM. Pay close attention to the spot where the harness transitions from the engine to the firewall, it is a common spot to have problems with chafing.

c4_4ya

You may want to have the ICM tested or replaced again. I've gotten bad ones from the parts store for both my '85 and my '92. The '92 ICM and the way its mounted/cooled has issues with heat. There are several threads on this forum that talk about this issue and how to fix it, use the search to find them that's what I did. Good luck man!

chopperclay

Wow, I jiggled the harness around from ICM to ECM and it started and is running fine. I'm letting it run for a while and will see if it restarts once warm...

c4_4ya

Awesome! Progress is good. If it still has problems starting when warm, check my last post about the ICM and heatsink issues!!!

Also, really try to find the offending wire/short and wrap it up good otherwise it will likely rear its ugly head at a very inopportune time!

chopperclay

It finally died at which time I was getting a SYS light pop up and abnormally low temp readings. The digital temp showed only 90 degress while the temp needle was getting toward the extreme end-

chopperclay

Thanks and will do C4!

c4_4ya

Find that shorted wire! I bet if you read out the codes, it will give you ECM or CCM serial data line errors...

chopperclay

Checked the DTC and got another C41, Cleared the code and started up fine...

c4_4ya

Was that C41 in module 1? That is loss of serial communications most likely between the CCM and ECM. You have an intermittent short. The good news is that you now know what you're looking for. The bad news is that it will take patience and persistence to find it.

What I did was this: I used a DVM to measure amperage by connecting one lead to a pin in the ALDL, and the other lead to chassis ground. Key on, car off I went through each pin until i found power to ground from the ALDL pinout. Mine was the brown serial line (CCM/ECM communications). Then I traced that wire everywhere through the dash until i found where it was pinched and found where the copper was exposed and shorting.

chopperclay

HMMM, Is the CCM behind the radio? Never been to or seen the CCM.

c4_4ya

Yes it is. But I would be willing to bet that in your case (like mine) the answer is to start looking around the steering column since you were doing some work in that area. You shouldn't need to worry at this point with trying pull the CCM.

desertmike1

Was your code a DTC41 Module #4 or was it a 41 Module #1 ? If it is a DTC41 then this is a fault code for the ICM not receaving 4.5 volts. This is giving in the video, and should be tested on the car at both the ICM terminal, and the ECM terminal with a good Quility DVOM.

When you remove any of the connectors make sure the (pins) and (sockets) are absalutely clean and shiny, if there is any corrosion at all this could be a problem..

I would spend some time and go over all of your (Grounding) points, and make sure they are clean and tight.