Non Buick Help Needed: Directly Wiring Taillights

[The Blob]

I've got an old Jeep truck that keeps blowing the fuse in the tail light/dash light circuit (blinkers and brake lights work fine). It is not worth it to me to spend a lot of time chasing down the cause so I thought I'd just hardwire the tail lights to the battery and use a toggle switch on the dash to turn them on and off.

Gave that a shot yesterday. Took the tail light assembly apart, but no matter which wire I connected the power to, they would not work. The best I got was a very dim glow. I could get the brake/blinker filament to work, but not the regular light.

Obviously I'm missing something. Can anybody help?

 

[John Larkin]

So what you're saying is the running lights are dim, but the blinker/brake are plenty bright? Sounds like low voltage which could be attributible to poor ground most likely. My Pontiac had a bad ground on the headlights and once I repaired the ground, they worked good. It could be the dual socket that is bad. They are not too costly to replace (the ones with the two spring steel contacts in the bottom), particularly since they should be plentiful at the junkyard. Maybe a good cleaning of the socket would help.

 

[The Blob]

No, it wasn't low voltage because I was running a wire directly from the battery and I was testing around 11.5 volts.

There is a short somewhere in the circuit containing the rear running lights and the dash lights. The fuse will blow as soon as the lights are turned on. I want to make the truck at least driveable at night by by-passing the circuit completely and wiring the running lights directly to the battery, but the best I can get is a very, very dim glow.

The new socket idea is a good one. But assuming the sockets are all OK, supplying one of those wires with battery voltage should make the lights come on, no?

 

[John Larkin]

This may sound crazy but make sure you have the bulb in correctly. I've put dual filament bulbs in wrong (they have the stepped slots that are offset from one another). If they are in backwards, there is a potential that they won't work right. I'm out of ideas. Just be careful running straight power back there unless you isolate the circuit completely from the harness. It could backfeed and cause a short to ground or worse.