justagoodolboy

Anyone know why my reverse lights dim when I hit my breaks? I've also noticed the dash lights and radio dim a little too. I've checked every ground I know of. Thanks!

Chrisreyn

Is this constant or only when the truck is cold?

Why not try measuring the voltage at the light sockets?
Search for some sort of drain that is pullign voltage from the reverse lights..IIRC correctly they share a common ground?
that would be my first check. then check back along the circuit to the running lights, and on back to teh HL switch ... there has to be a short in there somewhere...

Better yet, check your HL switch and associated wiring first for signs of overheating or melting.. that is very common.

justagoodolboy

I changed the switch about 2 weeks ago because my running lights had went out hoping that would solve the dimming problem but didn't. I could wiggle the **** and the running lights would blink, but they would not stay lit. It did fix that though.

Any clue where that common ground is your talking about? I guess it'd be a wire coming out of both tail lights back to a common point?

Santaclaus

If you have a digital voltmeter check the ground wires at lights. You might actually try some out and clean the connections almost always gets a ground problem at the tail lights. You also might check in this method.
Turn on your headlights, put the truck and reverse then step on the brakes my guess is you would not have any lights in the back. What seems to happen is when you lose ground to lights start backing up through the other ball and back through the system. If they all have power this can't happen.
Good luck,
Mike

06RAM2500

Do you have a 5th wheel or trailer plug installed??

Chrisreyn

If I recall correctly, the ground for both the back-up and brake light sockets join and go to a common ground wire back into the harness... I had issues with my tail-lights once and replaced the socket and ran teh ground to the fender well behing the rear tires, solved all my problems!
Check in the stickey for the wiring diagrams for a 91.5.. the lights wiring is the same throughout the first gen trucks