i don't know what the problem is!?
 

I have just recently done a ground up restoration on a 1969 gmc 3/4 ton 4x4 and when i drive with my brights on, after about 5 mins. they start flashing on and off really fast and just start freaking out like that. i will turn the brights off for a while, then turn them back on and they will work for about 5 mins. again until they do this again... what can be the problem!! this is really frusterating for me!!

Re: i don't know what the problem is!?
 

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I take it that both lights are doing it. To me that would rule out the sockets on the back of the bulbs.

I would say it's a connection that is heating up, or possibly the contacts inside the light switch, or maybe the dimmer switch.... Quite a few possibilities here. I would start with the dimmer switch because it is the easiest part to replace. Make sure that the contacts inside the plug are not corroded on it. Maybe a place to start anyway.

LockDoc

Re: i don't know what the problem is!?
 

There is a circuit breaker on the back of the headlight switch that is probably getting overloaded by the power needed to run your brights. Did you go to some custom lights when you did the restoration? If so you may want to do the relay upgrade to your headlights.

Re: i don't know what the problem is!?
 

I had the same thing happen years ago on an old chevelle. Was the voltage regulator. It can't handle the load so trips in and out.