Lights go on and off

'46Ford

'46Ford

Junior Member
I have a 46 ford sedan, all stock, 6 volt system. The lights, all of them, headlights, tail lights, dash will all come on and function for a while, approximately 5 minutes, then they will turn off for several seconds and then come on. This will be repeated sporadically. I have a generator on the vehicle. The amp meter on the dash shows charging and appears to be functioning okay. Any ideas on where to go with this. Could it be the regulator? I have checked all connections, everything seems tight. Thanks for any help.
 
Does this happen while you're moving and or stopped? Could be a bad light switch or connection being bounced around, if it happens while moving.
 
Could be the thermal cut-out under the dash attatched to the firewall, either faulty or the light circuit drawing too much current
 
Yep, I would check the circuit breaker first, it is the CB or a loose connection in the lighting wiring.
 
I did replace the light switch. The lights go on and off while sitting still, not moving. Not sure where the thermal cut off would be or what it looks like. I will look and try to check that out. I guess that is the same as the circuit breaker also mentioned.
 
The circuit breaker board is in the passenger compartment about in the middle of the firewall. Your '46 should have the "newer" two-section breaker, covered by a perforated metal box-shaped enclosure to ventilate it.

When I first had my '47 the circuit breaker would cut-out and in just as described if I had the head lights and heater on at same time. Turned out the CB was okay but (in my case) the alternator was wired incorrectly, couldn't keep up with the systems needs, so the CB would shut it down .... No fun at night on a country road. I corrected the alternator wiring and some of the system wiring and all has been okay.

Circuit breakers can be hazardous. They can fail, overheat and burn up a car, even with the engine shut off. If you hear them continually giving-off a clicking sound, disconnect the battery ASAP.
 
Last edited:
Yes the circuit breaker is in fact a thermal cutout. It is designed to heat a bimetal strip with the electric current passing through it and if it gets too hot then it opens the points cutting off the load until the bimetal strip cools down again, thus the lights etc. will cycle on and off. I think it is intended to prevent a short in the electrical circuits burning out the wiring and in turn causing a fire in the car.
 
Hi there, If by chance you have fitted QH headlamp bulbs which have a higher wattage than the original ford sealed beams then the extra current draw may cause the circuit breaker to flick on and off because its amps rating has been exceeded. Regards, Kevin.
 
The circuit breaker should look something like this. The unit on the left is the ignition coil resistor and the unit on the right is the circuit breaker.
 

Attachments

  • $_35.jpg
    $_35.jpg
    13.5 KB · Views: 11
Have you recently done anything that involved the electrical system or moving wires? How long has this been going on? My 46 was doing the same a few years ago and after replacing the circuit breaker, everything was good-to-go. There are plenty of NOS available-I got mine from Mac Van Pelt. Hope you are able to resolve the problem soon.
 
You must log in or register to reply here.
Back
Top