Window electrical short

[Northbound]

Well I just finished repairing the wiring in the window circuit of my '89 Silverado. I'll just post a brief description of the fix, as I see this could be a fairly common problem. The right window could be operated down but not up, from the left side (driver's) switch. When commanding up, the lights would go dim as though there was a dead short to ground in the window circuit, which there was. After disconnecting the harness from the right door by pulling the harness out of the front cab door opening structure and disconnecting the plugs found inside, the short to ground was still there. This meant that the short was in the harness between the left and right side of the truck. Here's the problem — the window and door lock wiring harness runs along the top of the inside of the firewall in front of the firewall insulation blanket so the whole instrument panel and dash has to be removed, which is quite a job. I disassembled enough to move the whole dash aft about 6 inches, which gave access to the harness. I found the harness to be draped over 3 or 4 hard points with no protection other than the black electrical tape used to wrap the harness. I found the harness had chaffed through on a canted firewall support just right of the steering column support. The support had very sharp sheet metal edges, and was a really stupid place to drape a wiring harness over without any anti-chaffing protection. The support had chaffed through the insulation on 4 of the 7 wires in the harness, but fortunately not the pink power supply wire, which would have shorted out the whole window system. ... really stupid design and really poor manufacturing techniques by GM.