Headlights flickering and no dash lights!

rubiarubia · Aug 6, 2011

Hey everyone!

This is my first "help!" post here. I've been lurking for a bit and you all seem very helpful, so hopefully you might have some answers/suggestions for me!

I have a 67 coupe (302 c4) that sat for a couple of years while I was out of the country. When I got back, the headlights were being a little finicky (sometimes turning off for a split second when switching to my brights), and the tail lights, dome light, and instrument panel lights weren't working.

I replaced the headlight switch, thinking that was something that controlled all those things. It made the taillights work, but now my headlights are flickering like crazy, and still no instrument panel or dome lights. I did replace the fuses for those (though the contacts are a bit rusty, despite my efforts to clean them up). I also replaced the dimmer switch.

One of the contacts in the headlight switch plug seemed a bit loose, the blk/org one that I've found out is the battery feed.

When I press the plug and switch together hard, on the back corner where that battery feed is, the headlights seem to work fine (until I let go). But no luck on the dash lights.

Help please! I'm a bit of a dunce on the electrical side of things...

Thanks!

Realmongo · Aug 6, 2011

I am wondering if this car was exposed to either a lot of humidity or salt air while it sat and all he connections have tarnished.

rubiarubia · Aug 6, 2011

Yes, it was on the northern California coast. I've just spent the last couple hours on it, and somehow got the instrument panel lights working (think it was cleaning the fuse contacts a bit more that did it), but the headlights are STILL flickering. It's driving me batty.

And scratch what I said about pinching the plug and headlight switch together. Doesn't change anything.

I have constant flow to the dimmer switch, and from the battery wire. The contact on the battery wire is perfectly clean (I pulled it), and none of the other lights that flow out from the headlight switch are flickering.

Suddenly, though, now my parking lights aren't working (after I properly mounted the headlight switch). Eh, I can live without that, although I would like to fix it eventually. But my headlights are prrrrrretty important!

Any ideas?

MitchGT · Aug 6, 2011

if it ain't power, it's ground. Make sure all of the ground connections are clean and tight.

Realmongo · Aug 6, 2011

Do they still flicker with the engine off? If not,then you may have a bad diode in the alternator that is allowing AC ripple into the electrical system

rubiarubia · Aug 6, 2011

Yes, they flicker at all times.

Where would be the ground for that particular circuit? It would have to be JUST for the headlights since they're the only thing giving me a problem.

Also, I was wrong about my parking lights not working. They're fine

71fordramair · Aug 6, 2011

my 71 had the headlight flicker but not the dash light problem. the highbeam switch was bad ,warm to the touch. 12.00

Realmongo · Aug 7, 2011

71fordramair said:
my 71 had the headlight flicker but not the dash light problem. the highbeam switch was bad ,warm to the touch. 12.00

That was my thought also, but he stated he had swapped it out and still had the problem.

JonK · Aug 7, 2011

You're going to need to do some wire testing with a test light and ohm meter, you can get a test light for <$5 and a good ohm meter at sears on sale for <$20 normally. I didn't have dash lights when I got my car and found that someone had cut the dash light feed under the dash looking for a hot for the radio but never spliced the wire back one they discovered the radio didn't come on if the lights weren't on....

I pulled the gauge pod and laid it in my lap with the pigtails connected but also had to ground it to the metal dash once found the hot wire to get them to come on for my uninstalled test.
TMK all the power for lights goes through the HL switch, it acts as a relay/fuse, except maybe the brake lights? If your fuse box connections are rusty at all I'd replace it. I wish I would have replaced mine with a new blade ATO style box with more circuits when I had it loose. If there is rust on the connections you may never get the electrical problems to stop. I think the dash grounds are on the metal dash frame, you see the black wires/screw when you pull the gauge pod.
Jon

rubiarubia · Aug 7, 2011

Yes, I have replaced the headlight switch. (Also, I'm a girl )

Thanks for the tip, Jon. I did finally get the instrument panel lights working a couple days ago, but the headlights are still not steady. I do have a multi-meter, but this is one of the first electrical problems I've had to troubleshoot, so I'm not sure I'm being as thorough as I need to be. Hence the post for help!

Also, I don't know if this matters, but my horn is baaaarely working. I hear a faint sound when I push on it. Is that somehow related to the headlights?

Thanks!
Cassie

John in AZ · Aug 7, 2011

Just for a quick test hook a wire from the neg battery cable to the core support nice clean metal for a good ground & see if that helps either of them. They both ground up to that area so maybe something weird like a bit to much coorosion (sp) in that area.
John

rnrjunkie · Aug 8, 2011

The ground for the headlights is on 2 ring terminals that are under the bottom screw on the voltage regulator. (drivers side radiator support)

rubiarubia · Aug 8, 2011

Okay, checked grounds and everything seems to be fine. Cleaned the contacts on the voltage regulator, too.

Very interesting development, though: when I unplug one headlight, the other one stays on perfectly. Works on both sides. But when they're both plugged in, they flicker like crazy... Aaaaah!

JonK · Aug 8, 2011

You do have the '67 wiring diagrams to go by?
1967 Mustang Wiring and Vacuum Diagrams

I'm wondering if the wire that transitions between the 2 headlights is weak, strong enough for one headlight draw but not 2? Odd.
Jon

rubiarubia · Aug 8, 2011

Yes, that seems to be the case. I've heard of that happening when higher-powered aftermarket headlights are installed but I don't have those (to my knowledge.. though I haven't changed the bulbs in years). They used to work just fine.

I've heard there's a relay you can put in, so the switch just controls the relay, and then the headlights are fed directly from the battery. Does anyone know anything about that?

Also, could it just be that my battery is old/weak?

Thanks!

Rusty67 · Aug 8, 2011

rubiarubia said:
Yes, that seems to be the case. I've heard of that happening when higher-powered aftermarket headlights are installed but I don't have those (to my knowledge.. though I haven't changed the bulbs in years). They used to work just fine.

I've heard there's a relay you can put in, so the switch just controls the relay, and then the headlights are fed directly from the battery. Does anyone know anything about that?

Also, could it just be that my battery is old/weak?

Thanks!

I was going to suggest adding the relay in, its a better system all together and greatly increases the life of the headlight switch as well as the performance of the headlights at idle.

Also, is it possible the headlight switch you got is a bad part ? You didn't seem to have this flickering problem with the original switch. Obviously it was bad because you had all sorts of other issues that putting the new switch in fixed, but the new one my have a bad head light circuit. Try putting the original back in and seeing if the head light flicker goes away.

horseballz · Aug 8, 2011

If you do the relays (highly recommended) simply make a new harness with #14 wire (minimum) from the relays to the headlights and use the headlight wires/socket closest to the relays for your control circuit. Of course you need to make sure the switch is working properly, although if it works fine for just one headlight, it should be strong/sturdy enough to operate the relays. Replacement switches are notorious for being electrically weak, especially if the headlights have been upgraded even to halogens. You should check to see if the bulbs are indeed halogen.
Just My $.02,
Gene

rnrjunkie · Aug 9, 2011

I would try another switch...

Headlights flickering and no dash lights!

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