I have a 65 coupe with a NMN 350. Early this winter I replaced my instrument panel wiring harness complete with fuse box. As part of this upgrade, I also replaced both the power window and the headlight circuit breakers. The headlight switch was also replaced. It took me 4 weeks to accomplish the job but it turned out well and everything checked A-OK. When I checked the headlights, they were on for only a short time period.

Last weekend I entered the car in a local show and during the drive home, I exercised the low/high beams during the drive. The low beams worked perfectly but when I activated the high beam circuit, they flashed with the rhythm of a morse code message. Additionally the dash lights flashed. Switching back to low beam mode, they returned to normal ops. Once back into the garage, I duplicated the problem.. Low beams (no problem), High beams (flashing). I suspected either a bad dimmer switch, radiator support ground, or headlight switch wire not making full contact. I could not find anything obviously wrong. I thought the circuit breaker was protecting only the headlight motors. This car is almost acting like a CB is cutting the high beam circuit on/off but I'm not certain.

Has anyone had any experience with this situation before? Can you offer some direction? As usual, thanks guys .

 

You either have a bad circuit breaker in the headlamp switch, or something in the circuit is drawing enough current to make the breaker open and close as it should when it sees overload. Check your lights to make sure all the filaments are working as they should including the tail and park lamps.

 

The headlamp switch has a overload function built in. The high beam currant is to high for the switch. I have always added a relay to the head lights feed from the horn curcuit and have found the voltage will improve at the lights by 1 to 2 volts. Better lights and less currant going thro the switch.

 

If only happening at high beams could be the dimmer switch. Cheap and easy to replace.

 

very unlikely the dimmer switch would flash rhythmically. Headlight switch cb either weak or detecting overload on bright much more probable. Also the dimmer switch would not flash the dash lights, the headlamp switch protection would.

 

Put the original headlamp switch back in and see if problem remains. If it does then something else is pulling way too much current when the high beams are turned on. Go from there.

 

Thanks to all of you that responded. Your comments have made me recall that during my wiring harness replacement, the old headlight switch began overheating. I disconnected the battery and removed the switch replacing it with a brand new one. I was assuming the old switch was old and for some reason malfunctioned. With the new switch and the successful checkout, I felt the problem was solved. Now I'm sure something in the system was overloading the original switch to cause its malfunction and I need to find out what it is.

From what you guys are saying, the C2 headlight switch has its own protection built in? Is the remote headlight CB protecting only the operation of the electric headlight motors or the entire circuit?

Thanks again for any input. I'm not sure exactly where to start on this troubleshooting. Maybe disconnect the headlamps individually will isolate the problem. Is it coincidental all this happened when I adapted the new harness? I don't know what the install error could be since everything was clearly identified going into the car. I feel a headache coming on. Maybe an adult beverage is now in order.

 

Reproduction electrical parts aren't always the best. Your high beams only have to be on "the edge" to cause the strobing problem. And a dimmer switch could absolutely cause the thermal cutout in the headlight switch to activate if it has a high resistance - just like any other marginal part in the circuit. IF there is no other problem in the circuit relays are an excellent way to offload the current from the switch and there are lots of posts on this. I had this EXACT came problem on my '61 with a repro headlight switch and put relays in 4 years ago with no issues since.

 

Thanks for the advice. I plan on doing a quality control check of my harness work this evening. I take another look at the previous posts concerning this problem. Seems its always the little things that are the most frustrating.

 

Higher resistance in the dimmer would lower the current. So still don't think the dimmer is the problem. You may have a headlamp drawing too much current, or wrong type. The headlight switch has it's own protection and the cb you're talking about is for the motors. Remember the current goes through the tail lamps and dash lamps and parking lamps too, so it could be in any of those.

 

Ok got it ,I know exactly what's happening you need to get this from
summit racing http://www.summitracing.com/parts/rfw-hr56/overview/
The picture shows the circuit breaker that's open and closes with the high beams on it designed to do that to protect the harness. Its inside light switch housing.
Reason is you installed quartz headlight's ,they pull move amps than the stock headlights. To split up the circuit you need to buy the part from summit .This part hooks to the high beam switch on floor ,then you pick up new circuit from the fuse panel when you put high beams on they have there own circuit. I had to do this on both split windows. Even if you didn't add quartz this will fix the problem .

 

Sherpapilot,DID you install non-stock headlamps?

 

Yep. I have been using halogen high beams in this car for 8 years but never experienced any problem. It wasn't until I replaced the wiring harness that a problem developed which made me think I didn't do something correctly. Your solution certainly makes sense. I still have the bulbs that were in the car when I bought it in 2003 and will switch them back around tonight. Wow, that would be an easy fix. If that works, I can always do the relay mod as suggested and run the better high beams in the future. Thanks for the input.

 

yea you can have a cold tonight ,its almost easer to do the mod than go back to dim lights ,every mid year I have has this mod when I drive at night I like to see good.
Good luck

 

A theory, the new wiring and connections provided enough less resistance to increase the current enough to trip the breaker in the switch.

 

I have Halogen Hi's and low's in my 67 for 30 years now - Original headlamp switch and stock harnesses and no mods and never have had one issue.

 

The old harness were 30 amp I don't know for sure it had to be less
then the old one it heats up and flicker's it doesn't trip.

 

My headlight switch has never been removed from the dash since day one - it never gets warm and everything including the original clock and radio still works!

 

Not the switch the breaker bolted to the side where carpet kick pad is
That's what carries the load here's a picture

 

Gentlemen, tonight is successful. I switched out the bulbs to confirm the problem and sure enough all returned to normal. 65GGvert's theory about the new harness is most logical because the old one had a large voltage drop, enough to kill the radio. If I pushed on the fuse block, voltage was restored. Pulling the fuse block indicated lots of corrosion inside. Because this was a fire getting ready to start, I changed out the harness with a brand new one to include the fuse box. The old headlight switch immediately overheated which also confirmed it's poor condition. After replacing the new switch, the new internal CB did its job by cutting out the high beam circuit with the more efficient harness. I plan on living with the original high beams for the time being until I can mod the circuit with the relay. This just goes to prove you can't trust 50 year old wiring. Once again, thanks to the great Sting Ray owners that helped me out with this problem.