Vehicle: 2003 Chevy K1500, 4WD, V8-4.8L, VIN V

Mileage: 238,782

Problem: The vehicle was dropped off at the shop because the turn signals would operate at standard speed only when no other lights were in use. If the brakes were applied or if the headlights were on, the turn signals began flashing much faster than normal.

Case Details: The technician checked all the bulbs and they were correct, in good shape and were making good contact in their sockets. He also verified that all the other lights throughout the vehicle were working normally. A quick call to ALLDATA Tech-Assist provided the technician with a good idea of where to start diagnosing this problem. The consultant suggested to first check the grounds related to the lighting system for being loose or corroded and provided their locations (see chart).

The technician inspected grounds G100, G401, and G403 and found them all to be rusted. Not only were the ground wires and connections rusted, some were almost broken all the way through with only about half the wire strands remaining.

Confirmed Repair: The technician cleaned or replaced the ground connectors, repaired the wires, cleaned the contact points on the chassis and reattached the connectors with new hardware. After the repairs, the turn signals operated as designed even with all the other lamps in use. Problem solved!