Thanks for all the guidance everyone. The less hunting and pecking I have to do is very much appreciated. It's 100 - 110° out, so crawling around inside my Bronco is like working in a sweatbox and the less time out there, the better.
I have two Broncos side-by-side, the other is an '84, so it's nice to compare since its brakes work just fine.
On the '84, if I remove the plug to the switch and check the voltage across the plug, I get 12.5v. If I repeat that on the '81, I get 2.5v.
If I check the plug on the '84 with the negative terminal for the voltmeter on a good frame ground, and the positive to the plug, one wire gets 12.5v and the other gets 0v. (Remember, this is with the plug unplugged from the switch.)
If I repeat this on the '81, one wire gets 12.5v, but the other (which was 0 on the '84) gets 9.5v. Both sides had voltage when it wasn't even connected to the switch.
Would bad bulbs cause voltage problems?
I understand the basics of electronics, but I'm not the best at diagnosing what things mean, so thanks for any help.
Heh, and no, Steve, I'm not seeing any ground there.