1999 Mustang GT battery draw:

What else is on the ignition fuse that isn't controlled by the ignition switch?

If there is nothing else, and there probably isn't, then the ignition switch should be shutting everything off. If it isn't, the switch is bad.

If there IS something else, it could well be an aftermarket radio or alarm system that was spliced into the nearest available wire. This is sadly a common cause of leakage problems.

--scott

Hi a buddy has a 1999 Mustang GT 4.6L that keeps drawing on the battery and dying when left for more than a day. The draw is significant enough that when you touch the negative cable to the battery, it arcs. Current draw on a dvom is ~5 amps. Thinking the alternator was to blame by ther humm it produced we replaced it. Same thing so we started pulling fuses. When the ignition fuse is pulled, the current draw stopped. Bad ignition?

Thanks!

Ford had a problem with ignition switches over several years involving most car and truck lines. If the draw stops by pulling the ignition fuse and you know everything is off, I would replace the ignition switch. The failure in the switch was wear of the contacts. The wear particles would collect in the lubricant in the switch to eventually produce a current path. The longer this goes on, the more current will be drawn until the current is great enough to overheat the switch and ignite. The switch is not terribly expensive. BTW, the switch is not on the other end of the ignition lock and key. It is down below the instrument cluster on top of the steering column. I think all of the switches made since about 2003 or maybe before are of the updated design.

Lugnut