PCM fuse blowing after replacing the transmission fluid & filter.

[paulpaul]

I have a 96 explorer 4.0, the PCM fuse keeps blowing when I try to start. It was fine yesturday, all I did today was change the Transmission filter and fluid, since then keeps blowing fuse, any suggestions??

 

[fixxxer]

Sounds like you may have pinched a wire somewhere in that area.

 

[BrooklynBay]

Welcome to this forum! This problem has come up a few times on this forum. One of the internal wires on the wiring harness is shorting against the transmission pan.

 

[paulpaul]

PCM fuse blow

Fixxer, thought the same thing myself, took pan back off a 2nd time and double check the entire area, wasn't near any wires at all. I'm thinking its just a coinsidence, but not don't know where to start??? Could the PCM be bad? Getting a continuity reading between the left side fuse port and car ground?? That should be the port receiving the power thru the fuse, but is reading ground, so as soon as I hit the ignition it blows, but not before. Thank You for your response.

 

[BrooklynBay]

Unplug the wiring harness going to the transmission, and see if there is still a short.

 

[fixxxer]

Is it Fuse 19 that is blowing? It should be a 25amp fuse. That's to the PCM relay. The PCM itself gets it's power though a 30 amp fusible link but it's switched on by the PCM relay.
Try to isolate the issue like Brooklyn suggested, unplug the transmission control wiring harness, it's either a 9 pin or 13 pin connector (if i remember correctly)

 

[BrooklynBay]

A cable tracker comes in handy for stuff like this: http://www.explorerforum.com/reviewpost/showproduct.php/product/285/cat/500

 

[paulpaul]

PCM fuse blow

Fixxxer / Brooklyn, unplug it at the Tranny or at the PCM? also, where is the PCM located? is it behind the firewall (passenger side)? The fuse blowing is the 30amp located in the power box in the engine compartment (1st one in line behind the last relay) Thank you both for your help.

 

[fixxxer]

Unplug at the tranny first, then if the fuse still blows you know it's a short somewhere in the wiring harness.
Looks like the location has been sought after before on the 2nd gen's. http://www.explorerforum.com/forums/showthread.php?t=215304
If you read through it, you find "The Gen2's the PCM is front top center of the firewall"

 

[paulpaul]

will give it a try, Thank You.

 

[fixxxer]

You're welcome and good luck.

 

[paulpaul]

PCM fuse blow

Well, looks like I'm going back in.... diconnected the wiring harness from the tranny and you were right, starts right up with out blowing fuse. So I will have to go back in and see what is making contact. Thanks for the help.