What the hell is causing this to happen?

Venom351R · Sep 9, 2009

I was driving down the interstate last night and my head lights started to flicker on and off. It stopped at one point but started again on the way home. When I got home I left it running and looked at it from the front and its only the head lights doing this, no interior lights and not the parking lights. They just get really dim or completely shut off and then come back on again, like flicking a light switch on and off.

Davis83 · Sep 9, 2009

It could be your headlight switch going bad, the connections go bad after awhile and lose contact.

urban96 · Sep 9, 2009

Davis83 said:
It could be your headlight switch going bad, the connections go bad after awhile and lose contact.

+1

pop off the headlight knob and the trim piece and check the wiring on the back of the switch. Sometimes when higher wattage bulbs are used the wiring in there will heat up and melt

HISSIN50 · Sep 9, 2009

Another vote. You'll probably find charred wiring. You can get a new connector if needed.

Do post if you have higher wattage bulbs. The headlight switch should have a circuit breaker, so as the circuit overloads, it opens and closes (like a hairdryer does when it starts to get too hot).

sgarrelts01 · Sep 9, 2009

Do you have stock headlights.

If not i have seen this on some aftermarket lights specially ones like the Halo lights, in my friends case it was just some of the wires he ran/spliced were getting a bad connection causing the light to flicker.

Adam95GT · Sep 9, 2009

think they got you covered.

Venom351R · Sep 10, 2009

Thanks guys

Yes they are aftermarket bulbs (and head lights but that's just the casing anyway) So Im sure this is my issue. When I have enough time when Im not working I'll check it out.

Thanks for the info

HISSIN50 · Sep 10, 2009

One solution might be to add a relay for the low beams and one for the highs (if you desire). It's quick and simple and really helps headlight output, even for stock wattage bulbs.

99FiveOh · Sep 10, 2009

I had this problem before, found the headlight switch connector melted. So I replaced the connector and thought I was good to go. Nope, still did it. The melted connector was just a coincidence. Turned out to be the multifunction switch (turn signal switch) that was bad.

If your switch is good/connector.. that's the next place I'd check.

HISSIN50 · Sep 10, 2009

Mark, it was probably more than coincidence. A failing MF switch or connections probably caused the headlight switch or wiring to overload.

Venom351R · Apr 18, 2010

Been awhile since I posted this topic but I just wanted to update it. I added these.

Amazon.com: Go Series (Model: 9007) Plug-N-Play Heavy Duty Headlight Wire Harness: Automotive

yesterday was the first time I got to test it out and when I got behind a car at a light I noticed that my headlights were still flickering. They were not doing it really fast as before. Now it was just slower.

What can I do now? Can I just put stock bulbs back in and end this annoying mess b/c I just want it fixed. I have enough going on with the car right now to have to deal with a stupid flickering head light issue. If I just put the regular stock bulbs back in that was meant for the car will all this go away?

Husky44 · Apr 18, 2010

Point your car at a garage door or wall, so you can sit still and see what is really happening. If your flickering problem went away while driving, and now only is appearing at idle (you said you noticed it at a light, so I'm assuming you were at idle), I'm guessing that you're seeing a different "issue". My headlights also dim/flicker some at idle, and I've always just attributed it to the underdrive pulleys not spinning the alternator quite as fast as it was designed. Not a big deal when you're above idle, because the RPMs are high enough that alternator's making sufficient electricity.

If you feather the gas to get it up around 1200-1500 rpms, do your lights get brighter and stay steady?

Venom351R · Apr 18, 2010

It was most likely doing it while driving. I had my headlights on b/c it was raining but it was during the day time so I could not see my lights in front of me. I just noticed it once I got off the interstate and pulled up behind a car at a light and I could see the reflection of my lights flickering.

Pokageek · Apr 18, 2010

Mine does this at idle a little bec of the cam. When I tap the pedal ,it goes away. That does not mean it may not do it on the bway I guess if the rpm's are too low ..but they arent now with the 3.90's.

Venom351R · Apr 18, 2010

well I guess I need to find out if its doing it all the time or just when I come to a stop then. But if it is doing it all the time whats the best thing to do to stop it? Put the reg size alt pulley back on ( I do have UD's) or get a set of stock type bulbs?

Venom351R · Apr 18, 2010

here is what its doing. I let it idle outside for awhile. It was not doing it until I turned the high beams on but when I put them back on low they still flickered. Hitting the throttle did nothing to make it stop blinking when the RPM's where higher.

Mustang Pics :: 007-14.flv video by TravisMcEwen05 - Photobucket

HISSIN50 · Apr 18, 2010

Did you add a relay to those extensions? If the issue is the headlight switch overloading its internal breaker, relays can help unburden the circuit, esp if you have non-stock wattage bulbs.

Otherwise make sure the lighting grounds are clean.

Husky44 · Apr 18, 2010

Venom351R said:
here is what its doing. I let it idle outside for awhile. It was not doing it until I turned the high beams on but when I put them back on low they still flickered. Hitting the throttle did nothing to make it stop blinking when the RPM's where higher.

Mustang Pics :: 007-14.flv video by TravisMcEwen05 - Photobucket

Huh...

If it didn't go away when you held steady throttle at say >2k rpm, it's most likely not your pulleys or alternator. I'm inclined toward Hssin's thoughts, that your lamp draw is too strong for your circuit layout. The relay addition is a pretty common thing to do in the firs gen Mustangs to help the wiring support a stronger bulb, but I'm pretty much completely out of my area of knowledge at this point.

If you've got stock bulbs laying around, I'd say throw them in next, and see if the problem goes away. That would be my next trouble-shooting step.

Venom351R · Apr 18, 2010

HISSIN50 said:
Did you add a relay to those extensions? If the issue is the headlight switch overloading its internal breaker, relays can help unburden the circuit, esp if you have non-stock wattage bulbs.

Otherwise make sure the lighting grounds are clean.

I just used the Plug and play wire extensions. Where can I get the relays?

HISSIN50 · Apr 18, 2010

At this point you can start over with an extension and relay kit, or just add a couple of SPST relays to your existing extension harness.

You can get relays at Radio Shack or use the ones they sell in the driving-light section of your local parts store (where the aftermarket fog lights are). You would likely want one for low beams and one for high beams.

Good luck.

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