Went to start my 91 mF250 w/7.3 and nothing. All the lights, etc worked. I then noticed the connection for the glow plug harness was smoking. Turned key off. Same thing a couple more times. Finally I jumped across the starter solenoid and it runs great. Smoke stopped after truck started. Any advice where I should start tracing the million miles of wire? Thanks in advance!

 

First off check the connection for good contact. Overheating or burning at a connection is usually the result of high resistance due to corrosion or the arcing of a loose connection.

 

Look on the right inner fender there is a large black connector or grey connector.... depending on year .....there have been considerable melted connections within these connectors. Most members remove the connector and wire direct...... solder and heat shrink.