Join Date: Nov 2009
Location: Redford, MI
Bronco Info: '96 Black 302 XLT - '94 Green 351 E. B. both are E4OD, 3.55 axles, 31 10.50x15
Your truck (and all Broncos) have a negative ground, that means that the negative terminal of the battery is the "ground". The negative terminal has cabling that connects the engine, body and all the other metal parts. As any circuit, by definition, has to be connected in a circle (circuit), the electrical flow starts at the battery positive, through the load (solenoid/lamp/radio/fan etc.) and then to "ground" which carries the current back to the negative terminal of the battery.
The paint acted like an insulator, and the current couldn't find its way home.
Usually, the threads of the bolts holding the solenoid to the fender and the flanges on the solenoid are conductors that brings the "ground" to the flanges on the solenoid. Internally, the winding of the solenoid core is connected to the little terminal (I) and the other end of the solenoid winding is welded to the frame of the solenoid.
Take an old solenoid and open it up (grind the rivets off), then you'll know how it works. It is not magic.
"The simplest solution is usually the best solution" - Occam's Razor
"The significant problems we face cannot be solved at the same level of thinking we were at when we created them." - Albert Einstein