Fan switch

[Jack21]

Problem solved. Always put high amperage accessories on their own separate power leads. 30Amp realays should suply the power from the battery to the accessory, and should have a 20 or 30 amp breaker (instead of a fuse) on it. Only the control side of the relay is controlled or switched. Fans, halogen headlights, horns, CD ignitions, sterio amplifiers need relay operated circuits. Minimum of 12 ga wire on power circuits.

Another headache saver if installed during the initial build is redundant grounds. Redundant grounds use the chassis frame only as a backup (redundant) ground. Although these can be made easily, Ron Francis wire works (wire-works.com) makes a ground strap that connects all ground leads directly to the battery ground. I used one on the engine side of the firewall, and a second behind it on the dash side of the firewall. All component grounds terminated on one of these two busses, which was wired directly to the battery ground. A frame to bus connection was also added.

If you've ever been driven nuts trying to diagnose intermittent grounds, or corroded grounds on steel bodied cars, you'll appreciate the simplicity and reliability of a redundant ground system.