O/T: '91 Dodge headlight problem

[Anonymous-0]

My brother has a '91 Dodge Ram, 3/4 ton, 4x4, Cummins auto. He's having a problem with the headlights occasionally blinking of and on. It started with the high beams, but now does it on low beams also(both headlights, not just one side or the other).

The way he describes it, it has a steady rhythm, similar to the way the turn signal flashes. He's watched the amp gauge when it happens. The needle doesn't drop, like something would be shorting out. We cannot recreate the problem in the driveway.

I could be wrong, but here are my thoughts: I don't suspect a loose connection, due to the rhythm. I don't suspect the switch, only because I've never had one act like that before; I've only seen a work/not work scenario with a switch. I'm thinking a bad circuit breaker or headlight relay. If there are other possible causes, please let me know.

I've googled for wiring diagrams, but I can't find one. Can someone point me in the right direction? Or possibly tell me where the headlight relay is located?

Thanks in advance to all who respond with suggestions and/or solutions. Your assistance is appreciated.

Sincerely,

Anthony

 

[rustyj]

Check your battery ground to frame or truck body-where ever the other end of the ground cable attaches to the frame of the truck. Also, check all battery connections, and take cable ends off where they bolt on the battery, and the ground cable where it is attached to the frame. Clean all with a pen knife, or buy a battery cable cleaner, with the wire brush on one end, and in the cap on the other end. Install new bolts at frame ends, and in cables. If it persists, new cables might do the trick. They get corroded inside the covers, and lower the asmount of current going thru them.
After all that, a bit of chassis grease on the exposed shiny parts will slow down any more deterioration. And also, make sure the battery hold down holds the battery in its holder tightly! And, if the battery isn't the sealed type--has caps, check the battery water level monthly, and apply distilled water with a tool that yer wife uses to baste the turkey or roast with! Don't get battery acid on it--tastes terrible on Sunday's roast!

 

[RayP(MI)]

Headlights are typically on a circuit breaker instead of a fuse. A short will trip the breaker, and it will reset again in a few seconds, leading to a flashing phenomenon. I would look for a short in the headlight circuit, and possibly replacement of the breaker, if it turns out to be defective. Am not familiar with your particular vehicle, but this is typical behavior when a short happens.

 

[ArleninOr]

I have a 93 that did the same thing. Thought as you did WRONG was headlight switch plug on switch was burnt Built new wiring for switch problem solved

 

[KSTractor]

I've had that problem with a '98 the head light rely was bad.

 

[Davis In SC]

Any chance that it could be somehow affected by the cycling of the preheater grid.. It pulls a lot of amps, just a thought..

 

[RWK in WI]

I don't know about a Dodge but on our Fords it means replace the headlight switch, plug connector, and if so equiped, the relay and problem solved.
I hope this helps you.

 

[doogdoog]

Aloha,
Yes, check your ground.

Mahalo,
doogdoog

 

[david from mo]

No relay from factory (i don't think) Circuit breaker is in head lite switch. Check wiring to switch for burned connections.

 

[shinnery]

On a 82 Chrysler Imperial I had the circuit breaker was inside the switch. It started with lights blinking off on Hi Beam (4 lites on). Replaced the switch and no more problems.
bryce