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My 66 f-100 has a problem with the headlights. After turning on the headlights,, after 10 minutes or so,, they start blinking on/off I may go 4 miles and no problem,, then here they go again-off/on/off/on Sometimes my dash light goes out also. I thought maybe it was the dimmer switch in floor. But when the dash lights went out,, I feel sure its the headlight on/off switch. Must I use an original ?? Or is there an updated one that will work(modern). Thanks for any input...Dan
The headlight switch is shot. When they are worn out, they overheat and trip the circuit breaker in the switch causing the lights to blink. You can get a new one at any auto parts store.
I agree that your problem is probably the light switch. All Fords of this vintage suffer from the same thing. My '65 Galaxie had the problem in '67!While it's true that you can probably get a replacement at any auto parts store, I seem to recall hearing about "issues" with some aftermarket switches. NPD has some NOS Ford Motorcraft switches that sell for about $41 (see page 14 of Catalog #8). There are probably several switches that fit, and if I remember correctly, the newer they are, the more likely they are to withstand higher loads. The one NPD sent me is P/N D3ZZ-11654-A. Good luck.
Replacing the switch is a good idea. But, have you installed an upgraded light system, like halogen bulbs? These systems tend to draw lots of current through these switches and may overheat them. Also I have found loose connections at the switch plug will cause overheating. Rotten and corroded bulkhead connectors can also be the problem. So the switch is responding to a high heat/amperage and actually doing what it is supposed to do---shut down the circuit. Use plenty of dielectric grease on the plug so that it seats completly on your new switch. To remove the switch reach up under the dash and feel for a small spring loaded button on the top of the switch. Push the button and gently pull the switch **** out, then unsrew the bezel and drop the switch out and down. Now is the time to unplug it. Install is the reverse of removal. There was an article in the tech section a few years ago that may still be there called whiter whites brighter brights that details how to install bosch relays to improve power to the lights and reduce the load on the switch. Good article!