Headlights shorting out

1.) it could be the headlight switch, do the lights in cabin itself like dash lights turn off as well? It could also be faulty grounds, check the grounds for the headlights. If a wire is corroded at one point it is most probably corroded all the way through, a 3" splice probably won't do much.

2.) If it's going to only be to the firewall and to the lights i'd just get 16 gauge wire and run it through, you're going to replace it anyway when you rewire. Same for the oil pressure, its easy to wire its a single wire that connects to the top of the sensor and then to the gauge.

As for replacement harness recommendations, i believe its either between Painless and EZ wiring.
Painless costs more but i hear its easier to install because its an exact or pretty close reproduction of the stock harness.
I used EZ wiring, i bought it for 120$ or something close to that, its a universal harness with 21 fuses, it uses mini fuses, the other fuses some can be hard to get ahold of I'm not 100% sure tho but that's what i've heard. If you do go with EZ wiring get the mini series not the regular ones, i heard the regular fuse one has a huge fuse box, mine on the other hand (the mini version) is a smaller than the stock mustang one. The tech support for EZ wiring is really helpful and quite a few ppl on the forum who have used either or. Also, EZ wiring makes you use the old connectors, for example the bunch of wires that come through the firewall, they come through a rubber plug called the master disconnect, there are two, that is a rare part, i couldn't find that anywhere, i was forced to use the old one, but i didn't use the ones that were badly corroded,


3.) i believe it is normal for that to happen, it happens on mine

What year is the car? 65, 66 have practically the same system not sure about 67+

http://midlife66.com/wiring/wiring.html

That is a great reference, it tells you where the grounds are and how the wires are run, specifically check out exterior lighting both the detail and the schematic.

The head light switch has a circuit breaker in it to protect the wiring to the headlights. Like everything, when it gets old they start getting quirky. Replace the switch. If you have Halogen replacement headlamps, do a search on Head Light relays. You might want to do this mod.

Has the steering wheel been off or changed?
Lack of lube on the horn contacts under the wheel will cause this condition.
If so, use a small dab up lith grease on the underside of the wheel on the horn ring.

PB

Does it do it on high beam AND low beam? THe power for the headlights all run through the dimmer switch. Make sure you check that connection and the switch.

Start with the headlight switch as it sounds like you are tripping the self-resetting breaker.

This happens all the time to people who have upgraded their headlights to halogens (or simple replaced them with off the shelf parts and un-knowingly upgraded to halogens in the process).

If the headlights are halogens, you'll want to install a headlight relay (do a search, there are a million threads).

Otherwise, you might want to change the switch just in case.

Had the same problem in my 72. Replaced the headlight switch and BINGO!

It seems like most of the time its the headlight switch. I've sold many headlight switches that cure the problem.

headlights

Here is what I did:
http://www.theclassiccougarnetwork.com/tccn2/index.html

The aforementioned link only takes you to their index. From there go to tech/How to, then restomod, and finally Halogen headlights.

Thanks