The Stovebolt Site Forums The Shop Area The Electrical Bay Brake lights/dash lights

Gotta question. When I hit the brakes or use my turn signal, the dash lights light up. Just started doing this. Anybody got any ideas? Thanx

The only way I can think of that this would start on it's own without someone moving wire connections is for one or more wires to have lost or worn through insulation allowing a short circuit to power up your dash lights.

Could be a bad ground on a rear light or the wires shorting together. Make shure your bed is grounded to the chassis.

Ten to one it's a bad ground at a taillight assembly.

I'd say it was a short in the circuit, a bad ground wouldn't make the dash lamps to come on, the tailights simply would not work. Could be in the light switch or bare wires in the harness.

Thanx for the hints. I'll get out there tomorrow and start trying to trace it down. The wiring is a Painless wiring harness I put in 8 years ago.

Just thought of something. I used the old headlight switch with the new wiring harness. Think maybe something could have gone haywire in that switch? Thanx for the help.

Not true, Bill.

With a bad ground to the taillight assembly the current from brake light filament can't find ground there, so it goes from the ground side of the brake light filament to the ground side of the taillight filament, through that filament to the taillight wire, back to the switch and out to the panel lights where it finds ground. This is a very common problem on old vehicles (and new European vehicles including Mercedes). This is the same problem when you see someone in front of you putting on their brakes and a taillight goes out. In that case there is a high resistance ground that can't carry the higher current of the brake light. The brake light and the taillight are lower resistance than the the dash lights, that's why they come on.

Pablos49, the old light switch won't have anything to do with the problem.

Baldy, I looked at the wiring diagram, I see what you are saying. Most cars I deal with don't have the dash lamps on the same circuit as the taillamp. So what it's doing is shorting in the housing due to a bad ground. I had a ground problem with my brakelamps, but the dash lamps never came on, the lamps simply did not work. I added a 1o guage ground wire from the bed to the cab, that solved that problem.

My brake lights were doing the same thing, it was a bad bulb. The base was loose, and the bulb had twisted until the wires for the brake lghts shorted with the wire for the turn signal light. When I put on the turn signal on that side, both rear lights flashed. When I put on the brakes, the dash lights went on! A new 1157 bulb fixed the problem.

It has happened to me more than once. The bulb being bad also will do this stuff.

Hey Guys,
Just found the problem. The 2 wires (one for tailights, one for brakelights) had a worn spot in the insulation and were touching. Found it when I discovered that when I turned on the lights, the right brake light was on. Cut the wires, resoldered them and put on new shrink tubing. Now no more dash lights when I hit the brakes. It's the simple things that getcha!!!

I agree w/ longbox, the ground would have caused a short and blown fuse or heated wires, but the cross (old telephone co. talk)- would allow something else to get voltage and almost work. but because the connection was weak it probably would have been intermittant.

sounds almost like the cars in an old walt disney cartoon w/ goofy behind the wheel.