i have a 91 D350. if the headlights stay on to long the lights start blinking on and off. i have replaced my head light switch and after a month or so the same problem comes back. also my running light fuse will blow at different times. i have traced all wires going to my running lights and have found no possible rub throughs in the wires and no place it could be grounding out.

 

Sounds like it could be a weak relay !

 

You should have a circuit breaker for the headlights. It sounds like it is getting weak. From what most people say you should consider changing to relays that will illuminate your problem with the headlights. You're running lights are most probably connected with your parking lights. Most probably ought to consider moving them off to a relay, though the problem might be caused the switch getting hot from the headlights. Good luck.
Mike

 

The headlamp switch has an internal thermal circuit breaker if you have too much current being drawn off the lighting circuit it wall cause the breaker to cycle.

Try to unplug 1 headlamp and see if it still cycles, something is drawing too much power either through too many lights, not stock super flamethrower headlamps or a short circuit somewhere.

I would have to check but I think the breaker should be about 20-amps.

Do you have any extra lights or gauges on the truck? Also if you drive with your dimmer rheostat in the DIM position it can overheat the housing and cause the breaker to trip prematurely.

I would install relays on the lighting circuit and make this the last switch you will ever replace.

I used to have a trick lowered 70 Mustang that I used to road race; it had if I remember correctly 9 Stewart Warner gauges plus tachometer all with #1898 lamps in the chimneys, 100-watt Lucas headlamps up front and one night at 85 MPH on PCH everything went black when the breaker tripped. After that scare I became a believer in relays and now use then for everything.

I was standing on the edge of my toilet trying to see my car out the window, the porcelain was wet, I slipped, hit my head on the sink, and when I came to I had a revelation, Use a RELAY

Jim

 

My head lights are also acting up, some times they dont come on when I pull the switch, they will come on but not till later, can you expand on how to use a relay??

Thanks


Andy

 

hahaha i love how you dropped a quote from Back to The Future!!! you only learn your lesson the hard way. and hopefully, as you did, others take your advice and read your threads in the sticky with their fixes.

 

That was quite a lesson in driving blacked out, I think I was at about 5000 RPM in 4th gear at the time.

I was hoping someone would catch on to the quote,
One of my favorites, they filmed that move about 10 miles from where I now live, Twin Pines and Lone Pine Mall is the Puente Hills Mall, it only changed after he ran over one of Mr. Peabody’s trees. And they also filmed on Bushnell St. in South Pasadena I work on some condos on that street.
I have a lot of trivia on those movies.
Jim