I just replaced the tranmission on my 1993 B250 5.2L by an independant tranny place. After 520 miles of driving the van with the new tranny, I tried to start it on the night after a very hot day in CA (Heat Wave), the van started and then turned off abruptly - no engine light, no clicking - nothing.

Traced the symptom to a blown fusible link in the engine compartment. I then found that when the 3 pin connecter to the overdrive solenoid on the transmission was connected, the link blew. Of course, the transmission place I took it to claims it is an electrical system issues and I should send it to a friend of his and for a day's work where he might find the issue. What they did mutter is that most of the time, things like this is caused by a bad computer.

Being an engineer I found the schematics for the van and found that the overdrive is connected to pins 54 and 55 of PCM with the middle DARK BLUE wire connected to the ignition and always hot.

Since the solenoid pins don't tone out to ground and the signature is a direct short to ground - blowing the fusible link, could the cause be the ECM/PCM? Isn't it a strange that the PCM connection to the transmission fails so soon after the transmission is repaired? Could it be that they screwed up the PCM during repairs? Would a failed PCM cause a direct short through the overdrive solenoid?


Could the transmission place used the wrong overdrive solenoid? - although the dude says he has 25 years experience with transmissions.

I looked at the wire harness by the transmission and things look OK. The engine computer seems to work and reports a short/open overdrive solenoind and short/open torque converter- codes 37 & 45.

Looks like I can get a rebuilt ECM for abouth $150 which is about 1.5 hours labor here and easy to install. Is this the first step in the process of elimination?

Lots of questions here, just another strange Dodge situation.

At least I have a shiney, new transmission.

I have attached the schematic for that circuit; if it helps.

 

So, I sent the B250 to the tranny place to test the solenoids; of course no problems. I then brushed off the ECM and the harness conections and tapped both a few times. Now the van starts without problems although it kicks out a lot of fumes from the exhaust as the ECM reprograms.

Problem gone away? Problem waiting for long distance trip?

Quite a mystery. We had a few hot days since, yet the fusible link doesn't blow. This is the time to get AAA.