Exterior lighting headlights: The headlights worked intermittently, flashing from low beam to high then off and back on. I am an aircraft mechanic, and I started diagnosing the problem, finding no ground to the headlights. Following the wiring diagram, this led me to believe that the dimmer switch portion of the combination switch on the steering wheel had failed. Upon further investigation, I found that the black/white ground wire for that switch on the wiring harness side of the connector under the dash was blackened from excess heat. Also the terminal inside the connector was almost melted. The wire from the switch itself to the connector is a 16 gauge wire, but the wire on the other side of the connector, going into the wiring harness to ground is only a 20 gauge wire. Each headlight is fused at 10 amps, with a possibility of a 20 amp draw on a 20 gauge wire. The nominal current draw for the headlights was almost 10 amps, which is certainly too much for such a small wire. For some time I had been smelling an electrical burning odor at times when driving the vehicle, and now I know where it was coming from. The wire was blackened, and the terminal melted, so a fire was a definite possibility.

- Atoka, TN, USA