The Stovebolt Site Forums The Shop Area The Electrical Bay Headlights flashing

RE: 1957 chevy truck

My headlights are flashing after being on for about 30 seconds.

I have checked all the connections and wires from the headlight switch thru the dimmer switch to the driver's side headlight on thru to the passenger side headlight. I pulled all the connections and applied dielectric grease to the terminals.

One note...If I unplug the passenger side headlight connection, the driver's side headlight stays on without flashing. IDEAS?!?!?

There is a thermal breaker in the headlight switch. Something is drawing to much amperage. What have you changed lately?

All that I did yesterday was replace the three bulbs in the in the top of the instrument cluster. Two of the three were burned out.

and while you were poking around under there you moved something so there's a short? particularly likely if it's old brittle wiring .... putting dielectric grease on the pins before plugging connectors together is a definite problem, it's an insulator, NOT a conductor, it's meant to be applied after connections are made to prevent corrosion ... if disconnecting the one side stops the thermal breaker cycling, most likely the problem is on that side, check there while you're cleaning off the grease

Bill

I had the same problem before. I replaced the headlight switch and been fine since!
Darren

Thanks, Darren.

I have one on order. Hoping this will solve my problem too.

Randy

perhaps a relay for the headlight circuit will fix the problem

Picking a part out of the air and replacing it is not a good way to troubleshoot electrical problems. If you are drawing too much amperage somewhere, changing a switch is not going to fix it. You need to find the problem before fixing it.

I agree with cletis. Before you go spending money on parts that may not be broken, pull out the multimeter and check the electrics properly. It'll save you a few bucks and tell you more about what's going on with the flicker.

Here are the facts.

1. I have instrument panel lights.
2. I have dome light.
3. I have turn signals, front and back.
4. I have parking lights, front and back.
5. I have brake lights.
6. I have license plate lights (rear)
7. When I pull the headlight switch know out to the headlight position...rear light remain lit, but after 15 seconds or so the headlights will begin flashing.

Regarding #7...here's what I have checked.

1. When I disconnect either one of the headlights, the other REMAINS lit continuously.
2. I have tried #1 on both headlights, respectively.
3. Using a multimeter, I have tested voltage on the headlight switch, dimmer switch connections, all connectors on the headlight wiring going
from the headlight switch to the actual headlights. I have done this combined with both headlights connected and individually on each headlight with
the other headlight disconnected. I have 11.5 volts consistently on power WITH NO fluctuations. Of course, this is with the headlight(s) lit.
4. I have CLEANED all terminal connections on the headlights with a electrical terminal spray on cleaner, from the switch to the headlight(s).
5. I have re-attached all body grounds using star washers.

So, what is left? What have I missed?

try bending the spring arms on the thermal breakers to tighten up the contacts and see if that at least makes it work a minute longer, also lightly clean between the points with a point file or some very fine emery - might fix the problem, or show the switch is the problem

Bill

I replaced my old switch with a new one from one of the vendors, and had the same problem you're having. Checked everything, every connection,ground, still couldn't fix it. Put a relay in and I now have lights that stay on. Easy and inexpensive to do.

Please reread what 'Cletis' posted. Too much current is your problem causing either a thermal breaker to cycle or another device/part to fail including a wiring junction. If the #3 test is correct and you maintain a constant 11.5 volt to the headlights at the switch then the switch is not the problem. Is it possible this thermal breaker is "downstream" of the switch? You might have to 'chase' the problem by using your vom with a sharp pointed lead to probe the wire(s) going to the headlights. When the voltage goes from constant to pulsed, back up toward the sourse and 'zero in'. You also need to look hard at the dimmer switch, you can wire around it with a couple of jumpers if necessary. Good luck.

Ran the test on by-passing the dimmer switch with jumpers. Nothing changed...

Still troubleshooting, wondering why this is happening. On the top of my (what appears to be a regular headlight bulb), appears "2X".

Would this indicate a higher power bulb and if so, could it be drawing more power thru the headlight switch than normal?

Thanks again for your thoughts!

Can anyone validate this...

standard and 2x standard (130/110 or something like that). 2x doesnt necessarily mean twice as bright, it means they use twice as much power.

As mentioned earlier, I have found that the two headlight bulbs installed in my recently acquired truck, have the "2X" glass markings on the top face of the bulb.

Could this be what is causing the extra power draw on the headlight switch and thus the headlight flashing?

yes, I'd say you have H7 bulbs [HID or Xenon], meant for BMWs, Audis and rice rockets .... why?? you should have T3 style [which may have a '2' at the top]
I believe the standard bulbs for your truck were about 110/90 [watts high and low beam] - as suggested above, if you want to "upgrade" to "modern" equipment, you need to do it the way the modern parts were meant to be used, with a relay .... is your problem on high beam?? not suprising

Bill

I did not install these. And since this truck was probably not driven during darkness very little or even at all, I doubt the prior owner ever noticed the flashing issue. When illuminated, these bulbs, certainly do not look brighter to me than an ordinary lamp.

As mentioned before, they flash on both low and high beams. My new headlight switch arrives today, so after trying that, if I still have a problem, I will look into a "stock" type of bulb as a test.

I cannot believe there are no identification markings on these headlight bulbs to determine mfg, voltage, type, etc.

Thanks for your reply.

Here's an update...

I received my NEW headlight switch today from Classic Industries. Installed it and all lights work. Headlights stay on without flashing. No other changes were made, keeping all bulbs in place.