I have been having problems with erratic tranny function. I have been trying everything I can think of and when I checked the Vehicle speed sensor for reference voltage I only get 2 volts rather than the specified 8 volts.

I noticed when unplugging the PCM connectors one of them appeared to be full of a yellow oil like substance. I originally chalked it up to the A/C that was leaking right under the PCM.

However having fixed that last summer and cleaned out the PCM plug it should not be back. I opened up the PCM itself and it has a yellow substance covering the entire circuit board, looks exactly the same color only not in liquid form.

Anybody have Any ideas? Looks like maybe the stuff is melting and coming out one of the plugs, possibly indicating the PCM is bad.

 

Lary: Not wanting to start a flame war here, but did you remove the emjay controller ? I don't know which circuits it uses but I think that there is a possibility to trace down the problem.<br>The yellow stuff in the PCM coul either be the corrosion inhibitor paint or some of the old muck you got around there when your AC was defect. <br><br>HTH<br>Markus

 

Markus I did remove the Strategy and found it had no effect on it. I did originally think that was a/c oil, but I opened up the pcm and can see the insulation in it is the same color.

My guess is the PCM has been getting hot, I noticed everything functions pretty good until I get about 120 miles on the truck or a 2 hour drive, then things go kaput.

I found that oily residue the day I went to install the Emjay Strategy, cleaned it all out and had already fixed the a/c leak, this is another batch of the stuff.and I believe it is coming from inside the PCM itself.

I am attaching a photo of the PCM you can see the stuff for yourself. Dark yellow looks just like the inside of the PCM itself.

This thing just looks like it has gotten hot and is leaking insulation perhaps.

 

Lary, that looks just like the corrosion inhibitor melting out. I don't know whether there are or aren't companies over there that do check and repair PCMs, over here the do. <br>I can only think of the following sources for extreme heat in the PCM: The generator field driver circuit(on C2),the 5V supply (C2) and the respective grounds. Since it does not act up until really hot you could try to do the following:<br>Fab a heatshield for the PCM and note if it gets better- then it should be heat coming from somewhere else. <br>If not you can look into the 5V circuit. I suppose if you do ovrload it you get too much heat. I'd also have my generator checked, because if you have a partially faulty winding you need much more power to create a sufficient field to supply enough electricity. <br>Be shure to clean all the contacts really good before reconnecting because a high resistance on the contact will also produce heat.<br><br>HTH<br><br>Markus<br>

 

Marcus it has graduated to not waiting to get hot to malfunction, what was once intermittant has become full time.<br><br> I made an appointment to have the PCM diagnosed but they can't do it for 2 more weeks I will probably just buy a new PCM and put it in rather than wait that long.<br><br> Obviously PCM's are not supposed to leak stuff like that so this one can't have much life left in it. I will note here that removing the Strategy controller increased the problem substantially, apparently the filters in it were able to help the sick PCM send somewhat cleaner signals than it can on it's own.<br><br> As I noted in my original article, the PCM was leaking before I hooked up the Strategy, and I made the wrong assumption that it was oil in the plug at that time. I never considered the possibility that it was coming from within the computer itself.<br><br> Thanks for your input Markus, I wonder how far I can toss this old PCM from the top of this mountain ;D

 

Sorry to hear about the PCM going out completely. <br>If you can disassemble the old pcm you can look at the circuitry for open solder points or the like. Have your generator checked, to make shure you don't fry the next pcm. I think the dead pcm could be a symptom not a cause.<br><br>Good Luck!<br><br>Markus