2000 GMC Yukon, Rear Lights Inop

This 2000 GMC Yukon came in with the complaint that at different times the stop lights, tail lights, turn signals and back up lights stop working. I did the basis bulb and socket tests and found nothing wrong. When I got to looking a little deeper in the system I found this rear harness junction block at right rear inner fender panel. I disconnected the harness connectors and water came out. Many of the terminals were green and this was the source of the lighting complaint. I carefully cleaned and tightened each of the terminals in the harness connectors and installed a new junction block. I also inspected and found that there had been accident damage at this point in the past. I had to beat the mounting panel back flat. I am reasonably sure that the junction had been cracked.

I informed the customer that if any of the problems returned we may have to start replacing harnesses. So far it has been 3 months and no problems as of yet.

I think that this is going to be a greater source of mysterious rear lighting problems on Chevrolet and GMC light trucks ( Silverado, Suburban, Tahoe, Sierra, Yukon, Escalade and Avalanche )from 1999 through at least 2007 Classic series. Maybe even newer models.

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