High beam headlights

[Tims1965MercuryComet]

When driving with the high beams on the headlights start to flash on and off after about ten minutes. Switching back to low beams the lights stay on. Switching the highbeams back on the headlights start flashing on and off. I replaced the dimmer switch with one from a 72 Maverick. Did not fix the problem. Could this be caused by a faulty light switch? All four headlights are halogen. I'm going to start working on it tomorrow morning. All opinions and advice will be very much appreciated.
Tim

[Groover]

I don't think it's the light switch. I believe all lighting power goes from the source to the light (on-off) switch and then to the dimmer switch. From the foot dimmer it either goes to the low beams or both hi and low.

If the switch were bad, I would think that it would flash/intermittent on both hi and low. The fact that it's only bad on hi tells me something between the foot switch and the hi-beams (or your 72 Maverick switch is also bad). Those things are not the best engineered thing in the world. Two copper contacts that toggle between the two positions. But it's either one or the other. So if your low beams work, then the light switch works and one half of the foot switch works.

Or maybe both lights together is too much current draw for the Gen/Alt but I'd think you'd blow a fuse then?

Least that's what I think.

[lavron]

My '62 Ford F-100 did that when I got it, changing the headlight switch fixed it. Been too long and I can't remember if it did it with high and low both.

See Ya,
Mike

[popscomet]

POP'S rule of thumb on this stuff IS...before you buy anything or work your butt off to change out different things.......check all points of connection,,check grds....jmo ,,good luck and thank you pop

[Lou's Comet]

Headlight switch.

Replaced a lot of them over the years. The high beams draw more current , that is why the problem occurs when the high beams are on. Pretty sure there is a circuit breaker built into the switch and that is prob worn out or the contacts in switch are going. But would bet you need a new headlight switch

Lou

[barrys65cyclone]

Replace Headlamp Switch . Breaker is weak

[Comechero65]

The headlight sw has a built in circuit breaker and that is cutting in and out because it is tired. Cuts out more on Hi beams because they draw more current than the Lo beam and the CB is just on the ragged edge. Time to replace the sw. While you are at it install headlight relays which will take the load off the sw, the sw will literally last forever then. Plus you'll probably have brighter headlights to boot.
I added relays to mine plus added a horn relay since ford did away with the horn relay in 65. I thought my horns were bad and was ready to replace them. But the relay saved them and now they work perfectly.
I installed new headlamp bulbs and discovered Sylvania no longer make the old sealed beams for the 4 lamp system on 65's. But their replacements are quartz and carry the same wattage rating.
I built my own relay setup with my own enclosure.
As an afterthought I probably should have split the power feed with 2 seperate fuses in case it ever blew I would still have the other pair of lamps instead of being in total darkness. I should pull it off and add another fuse.

BrighterheadlightsDual768.jpg (195.28 KiB) Viewed 3983 times

IMG_5243.JPG (165.55 KiB) Viewed 3983 times

Ron

[Tims1965MercuryComet]

Thanks for the replies. I checked connections this morning and they are good. Will be buying a new headlight switch at NAPA Friday.

Ron: what headlight relay did you use and where can I get them?
Tim

[Comechero65]

Thanks for the replies. I checked connections this morning and they are good. Will be buying a new headlight switch at NAPA Friday.

Ron: what headlight relay did you use and where can I get them?
Tim

It says Bosch in the diagram but they are just generic 30 Amp relays you can get at most any auto parts stores. I think I got mine from Radio Shack.

IMG_4439.JPG (38.5 KiB) Viewed 3943 times

The tedious part of the job was getting all the wiring layed out so it fit in the box. I used an old gen reg as the enclosure as it was bigger and 3 relays fit inside. Fuse included.

[Tims1965MercuryComet]

Ron: what headlight relay did you use and where can I get them?
Tim

It says Bosch in the diagram but they are just generic 30 Amp relays you can get at most any auto parts stores. I think I got mine from Radio Shack.

The tedious part of the job was getting all the wiring layed out so it fit in the box. I used an old gen reg as the enclosure as it was bigger and 3 relays fit inside.

OK. Thanks
Tim

[StPro]

I had the same problem with my 78 F350 . It is the circuit breaker in the headlight switch having a over currant problem. What I found was the old wiring could not carry the head light load due to oxidation on the wires in the headlight circuit. So take a good look at the wiring.

[Comechero65]

After 50+ years of exposure to heat and moisture it's not uncommon for poor connections to develop in any of the many points wher wires connect. That can drag down the power available to loads which can accelerate the cb in the headlight sw dieing a slow death and opening intermittantly. One of the things you need to do to refirbish an old car is to go over all the wiring and clean up all those many connections. Not hard to do on our older cars as they are not as complex as modern day cars.

Adding relays to the headlights is a big improvement for longevity.
Ron

[Tims1965MercuryComet]

Installed the new switch Monday, bought it from NAPA, one that cost more, not made in China. All the lights work. Will get a relay and wire that up next.
Tim

[Comechero65]

Very good on getting the sw replaced. You can usually find many different headlight relay kits on ebay if you don't want to build your own. I could have too but was a challange to build my own. Plus lots of time during the cold winter months when I couldn't do anything else. Plus for me I enjoy making or fabbing my own things.

Found a couple good candidates on ebay. Units for 2 headlights are cheap. Most almost double in price for 4 headllights. And other than possibly heavier wiring the only difference is 4 plugs for the lamps. They use ceramic instead of plastic plugs. Misht be better to order the kit for 2 lamps and two extra plugs and hook them all up. But found one set for the same price as for 2 lamps. $15.99

Ron

[thrnelson]

When I rewired my Comet Ron Francis recommended a relay system if I wanted to run all four lights at once for the high beams. They sold me the relay kit with great instructions. It works like a champ now.