93 JGC Keeps blowing fuses

[krazy3]

My 93 keeps blowing the the trans/ecm fuse under the hood whenever you hit a bump. I've looked all over/under the car and cannot find a bare wire anywhere. I'm not sure what all this fuse controls to narrow it down. When it blows, the car dies and the check engine light won't come on, other than that everything seems to work. Any help would be appreciated!!

[bringselpup]

If this were me I'd make up a 12v audible tester and put it in the circuit of the fuse that's blowing and go around and push all your cable harnesses. Wiggle every wire you can see to simulate the movement of hitting a bump. When you hear it beep you'll have found the harness that must be shorting out against the chassis.

[krazy3]

Originally Posted by bringselpup

If this were me I'd make up a 12v audible tester and put it in the circuit of the fuse that's blowing and go around and push all your cable harnesses. Wiggle every wire you can see to simulate the movement of hitting a bump. When you hear it beep you'll have found the harness that must be shorting out against the chassis.

I tried shaking and wiggling every harness I could get to with it running. Even underneath, all the transmission, O2 sensor and fuel pump as well. I banged on the bottom of the dash where the transmission control module is supposed to be with a rubber mallet. It all started in January, replaced the fuse, went a long time then again when my kid tried driving thru a frozen field. That went until yesterday and now it is whenever you hit a bump. I can't find a good schematic to find what this fuse controls to try and trace down the wires.

[krazy3]

Update: I traced the wire from that fuse to the connector on the crankshaft position sensor. Right now I can start it and I wiggle and tug on that wire and the wires down to the sensor and it won't die, Anybody had a problem withe the CPS like this before?

[krazy3]

Another update: It appears that this wire feeds the crank sensor, cam sensor, vehicle speed sensor, fuel pump and ASD relay, goes to the PCM and the TCM. I replaced the relays so they aren't the problem. The other night it did it as soon as I put it in reverse and it kept blowing them for awhile. Could the PCM or TCM be shorting out? The TCM controls a lot of solenoids in the tranny, could one of them be doing it? I've been all over this thing checking continuity and can't find wires shorting out.

[bringselpup]

Putting it into reverse and getting a blown fuse right away is probably the best and strongest indicator you've gotten so far. I'd focus my efforts in that direction either by getting a tranny shop to have a look or dropping the pan yourself if you're up for dealing with the mess.

[krazy3]

Originally Posted by bringselpup

Putting it into reverse and getting a blown fuse right away is probably the best and strongest indicator you've gotten so far. I'd focus my efforts in that direction either by getting a tranny shop to have a look or dropping the pan yourself if you're up for dealing with the mess.

I thought about that. I called a transmission shop to see if they had any experience with this problem, maybe it was a tranny solenoid. They told me they thought it was electrical. I'm gonna call AAMCO Monday if see if they have experienced it. The car's not probably worth sending to them unless they have experienced this problem before. I did find yesterday that one of the plastic looms was rubbing on the linkage. I was sure I found the problem. I pulled the wires out of the loom and they were all fine. It only blew the fuse twice when put in reverse. It blew it like 5 times hitting a bump. You could replace and keep going till the next bump.

[krazy3]

Just to let everyone know, I found a wire to the TCM that went thru the wire loom around of the back of the engine had a bare spot. It seems that the loom had laid on the back of the engine and this was the only wire that part of the insulation had melted off of. Definately has been a bear to find as it would only do it occasionally and I could just barely reach it, but last night I was able to get it to short and stay shorted until I could eliminate everything down to that spot. In fact I wasn't sure what had caused it until I tried to put the wires back in the loom and it crumbled.

Thanks to everyone for all the tips and suggestions as this was getting to be a big PITA!!

This forum is great, I'd be glad to pass along anything I can to repay everyone's efforts!!