Not sure, We got the car in October 2004 167k for $2000 DD put another $2k in for tires, radiator, shocks, nothing electrical... Our service tech did tell us the door was replaced and the Plastic door panel was shot ( the 7mm screw area is missing, panel was ripped off)

 

OK - Circuit 56 (BLK/WHT) is on the power source for the rear liftgate release. You need to trace this wire all the way back to the underhood fuse block.

Looks like the only thing that could cause this is the door lock switch malfunction where it allowed a short to ground and fuse was not proper.

Circuit 56 is fed from the 3A MIR/LKS fuse in the underhood fuse box, so make sure there is a 3A fuse in this position.

Attached PDF for Door Locks shows the schematic.
Attached PDF for C500 shows the big connector in your photo
Attached PDF for Door Connectors shows the little connector in your photo.

The other circuits to the door lock switch are named in the connector view.

If the shorted wire doesn't go all the way back to the underhood fuse block (liftgate relay) and only goes to the relay block near the door, then the power for the short came from another circuit.

Hope this helps.

 

Make sure to address all of the corrosion in the wires and connectors. Those points act like resistors which limit the current and prevent the fuses from blowing but heat up as that current passes through them like a space heater element hence the fire. Like Les says there is also the Possibility of improper fuse values.


George

 

Well this #56 fuse spot had a 30Amp in place of a 3Amp Also I tested the wire that was burn in the large connector, It was dead with or without the key on... And I pulled the #21 15Amp fuse from the dash side fuse panel ( it was labeled door lock)

 

MIR/LKS 3A Feeds:

Outside Rear View Mirror Switch, Door Lock and Side Window Switch - Left/Right, Lift Glass Relay, Liftgate or Endgate Lock Cylinder Switch

Do you want to fix or just disable? To disable just try leaving out the MIR/LKS fuse.

To fix clip out the blk/wht wire between underhood fuse box connector and pin B8 of C501 and hope Circuit 56 did not melt into any others under the dash. Run another wire to replace the melted citcuit 56 wire in the area that was clipped out. Then get a used door wiring harness with same options (mirrors, locks, windows, etc). Replace the Door Lock Cylinder Switch (one with 4 wires (blk/wht, blk, wht/blk, lt green going to it). Finally, install a 3A fuse.

Looks like the root cause was this switch and the wrong fuse.

Good luck and best wishes for a successful repair.

Here is the diagram for the pertinent IP wiring.

 

Well burnt wiring not a issue any more

DD survived... Blazer not so much

 

Whoa! What happened!



George

 

!!!!!!!!!!!!! Really hope it looks worst then what it was... that looked like a sweet ride! Would've loved to see it before.

 

Swerved to miss a deer, we think, roadway was wet, muddy light fog perfect storm of conditions I was about a minute behind her... She was trapped for 45 minutes... rural area
I've never felt so helpless.. Thank goodness younger people stopped to assist till EMS arrived

 

The Good side It was my daughters, I fell in love with it, even looking for me one She needs a Humvee