No tail lights

[Pittsburghkid]

I know its crazy but with electrical who knows what could be at fault. Have you checked the brake light switches or the headlight switch?

 

[RmvBfrFlght]

No still trouble shooting. Only works when 12v applied directly to the truck.

If the lights didn't light up when you connected the +12 volts to terminal F (BRN/WHT) of the fuse box connector, then the wiring in the conduit is open. Remove the sill plate, the wires run in the plastic piece under it. Check the wires the full length, likely broken someplace along there.

RemoveBeforeFlight

 

[87BuickT]

Under the "body by fisher" door sill plate???? drivers side????
Will it be a brn/wht wire?

 

[RmvBfrFlght]

Under the "body by fisher" door sill plate???? drivers side????
Will it be a brn/wht wire?

It will be BRN, not BRN/WHT like I posted (not sure where I got that from...).

Yes, under the sill plate with the Body by Fisher.

Just to clarify, at C209, terminal F, apply the 12 volts to the harness side of the connector, not the fuseblock side. Basically, unplug the connector from the fuseblock, find terminal F (BRN) on the harness end, apply 12 volts, and the tail lights should light up. Here is a diagram of the tail lamp circuit (click on thumbnail).

Look at connector C209-F and C320-C, the wire between them is what runs under the sill plate. With C209 at the fuse block, and C320 in the trunk. Also shows which bulbs should light up (RH same as LH).



RemoveBeforeFlight

 

[gsgnnut]

theres a break in the circuit somewhere it could be the light switch. You said you have power in it but did you check for power ( or continuity) out of the switch with switch operation? there should be at least two light feed leads out, one from the reostat for the dash lights and another for the tail and running lights. Good luck. Electrical gremlins can be a headache sometimes. Get a schematic of the lighting and chase it down. A volt ohm meter is a definate necessity here.

 

[Turbo6Smackdown]

Try this. (first of all, it's never fuses. that's way too easy) close your garage door so that you can see your brake lights/tail lights illuminate the door from looking in your rear view mirror. Start the car, turn the lights on with your steering wheel all the way up. If they're on, hold the steering wheel and pull the tilt lever. Now watch your lights as you slowly pull your steering wheel down. Do they go off at all? If so, you know the problem. If not, then hold your foot on the brakes. If they illuminate, you're good. Now while holding your foot down on the brake, slowly raise up the steering wheel again, while staring in the rear view. Did they brake lights go off? If they did, there's your problem.

I've been chasing intermittent brake/tail light problems since I owned this car in 2005. I must say though that I haven't chased them too hard. All I did was of course, check fuses,(they were all good of course) check bulbs, and check the wiring to the bulbs inside the tail light box itself. They were good. But after really getting annoyed at the last cruise with the on/off crap I read a boat load on here, and kinda diagnosed it by just reading. There's supposedly some wire that runs through the column that can get screwed with from the tilt mechanism. So I did what I explained above and sure enough, they worked just fine while the steering wheel was in the normal position for driving, but not when I moved it just a tad. They quit working then. So I would just turn them on and tilt the wheel and watch them go on and off with the wheel position. I would have never put two and two together had I not read this board.

 

[hiboom]

Try this. (first of all, it's never fuses. that's way too easy) close your garage door so that you can see your brake lights/tail lights illuminate the door from looking in your rear view mirror. Start the car, turn the lights on with your steering wheel all the way up. If they're on, hold the steering wheel and pull the tilt lever. Now watch your lights as you slowly pull your steering wheel down. Do they go off at all? If so, you know the problem. If not, then hold your foot on the brakes. If they illuminate, you're good. Now while holding your foot down on the brake, slowly raise up the steering wheel again, while staring in the rear view. Did they brake lights go off? If they did, there's your problem.

I've been chasing intermittent brake/tail light problems since I owned this car in 2005. I must say though that I haven't chased them too hard. All I did was of course, check fuses,(they were all good of course) check bulbs, and check the wiring to the bulbs inside the tail light box itself. They were good. But after really getting annoyed at the last cruise with the on/off crap I read a boat load on here, and kinda diagnosed it by just reading. There's supposedly some wire that runs through the column that can get screwed with from the tilt mechanism. So I did what I explained above and sure enough, they worked just fine while the steering wheel was in the normal position for driving, but not when I moved it just a tad. They quit working then. So I would just turn them on and tilt the wheel and watch them go on and off with the wheel position. I would have never put two and two together had I not read this board.

I like your idea except for starting the car and closing the garage door that's a good way to end up with a bad headache from carbon dioxide. Maybe turn to the on position and not start the car. I'm just saying.

 

[Turbo6Smackdown]

Just trying to replicate the exact situation my cars acts up in. And don't worry about the headache. If you've owned a Buick for more than a few years half of your brain cells are dead by now any how from "death by diagnosis" lol.

 

[hiboom]

Just trying to replicate the exact situation my cars acts up in. And don't worry about the headache. If you've owned a Buick for more than a few years half of your brain cells are dead by now any how from "death by diagnosis" lol.

Yes,I've had three all had issues none were the same they diffidently can be a pain in the but lol