Having a problem with the brake lights. Can anyone be of assistance?

When the brake pedal is pressed, the running lights (including dash lights, parking lights, and the low power filament in tail light) turn on, but no brake lights. When the lights are turned on and brake pedal is pressed, the brake lights do not turn on at all.

The 4 way flashers and signal lights work correctly with lights on and off.

Things I have tried:
Replaced the tail light bulbs.
Checked fuses (#5, #10).
Disassembled the brake switch and bypassed it with a jumper wire.
Checked the grounds (tail lights, rear ground, drivers inner fender).
Tried to trace the wiring. Didn't see any noticeable damage, but the wiring is in a loom so it is hard to see.
Used contact cleaner on brake switch, rear wiring harness, body harness.

Still hoping it may be something simple that I've overlooked. Thanks for any help.

 

I used to own a '94...and as it got rustier, the ground wire connections were always failing,,,causing me to remove and wire brush/scrub with sand paper to clean the grounding surface.

Based on your list, I wonder if your brake light switch is bad internally.

Keep us posted on your progress........ Thanks & good Luck!

BarnieTrk

 

I initially thought bad brake switch. But when I took the switch off and jumped the wiring, the problem remained. I took this to mean that the problem was not in that switch.

Are there any other grounds that I'm missing?
I'd like to narrow down where the problem is located (switch/ wiring/ fuse panel/ ground) but not sure what other tests I can do beyond what I have already done.

 

maybe this link will help,,,save and pass it along ,,,,,,Search Wiring Diagrams

 

The switches are cheap and often bypass will not work. Put a new switch in and then check. Get at autozone, if dont work you can return.

 

Ended up putting a heavy duty ground from the engine block to frame. But unfortunately that didn't work either.

I tested the body harness connection and that seemed to be working correctly. So I tore apart the rear harness and started tracing wires. Seems the previous owner spliced in new tail light wires and had them wired incorrectly. After some cutting and testing, I think I have figured out the issue. Now only remaining issue is the license plate light doesn't work for some reason.

 

UPDATE:
So I wired a mock driver's side tail light to test. I ran the lt green (brake)/ lt green with red (signal) to one light bulb terminal; brown (running lights) to the other light bulb terminal. I tested all the various scenarios - with and without running lights on. Everything seemed to be working correctly. I got new tail lights and wired them up. Brake lights and 4 way flashers work but now I have new problems.

1. With the right turn signal or left turn signal, both tail lights flash.

2. If I put the running lights on, the fuse blows.
-I thought I may have wired the passenger side incorrectly. (The one I didn't test!) I disconnected it and the fuse still blew. I disconnected the entire rear harness and the fuse still blew. 2 packages of 15amp fuses later, I still haven't found the problem. How can I test where the short is? I haven't touched any wiring anywhere else.

Thanks for any assistance!

 

I'm confused about the fuses and what could cause it to blow.

#10 fuse (keeps blowing): Turn/Stop/Hazard Lamps, High Mount Stop Lamp, Speed Control Amplifier, Warning Chime Module. Power supplied through fuse 2 of engine compartment fuse/ relay box.

Instrument illumination is #13 fuse. Power through fuse 2 of engine compartment fuse/ relay box, fuse 10, and main light switch.

When I turn on the main light switch, it blows fuse #10, not #13.
-Stop/Hazard Lamps work correctly.
-Turn signals are not functioning correctly, but does not blow the fuse when turned on. I disconnected the turn signal switch and it still blew the fuse.
-It blows the fuse even when the rear wiring harness is disconnected. When I had the brake light issues, I was able to test each pin in the wiring harness including the running lights. This is how I was able to determine how to re-wire the tail lights (when each terminal was hot for brake, turn, running lights, etc).

FYI - High mount stop lamp is not in use.
I'm not sure what the speed control amplifier looks like/ where located.
Warning chime module - I disconnected it, sprayed electrical cleaner and plugged back in. Did not open the module.

Going nuts here trying to figure this out.

 

turn signals sound like bad grounds need to recheck the work.blowing fuses you have a bad short someplace. You siad the PO wired in some stuff on the circuit. Had a neighbor having light issues and when I traced the wires found some of the inline taps that had corroded and were broken wires at that point. go to the spliced place and start from there.

 

Thanks for the reply, Hank.
What I don't understand is when I disconnected the rear wiring harness (where the spliced wires are located), it still blew the #10 fuse.

I previously had the rear wiring harness disconnected and it wasn't blowing any fuses. None of the other wiring was modified. Previously I added a new ground from engine block to frame.

 

Use/rig a test light, or 12 volt buzzer in place of a fuse until you find & fix the circuit short/overload. when the lamp goes out, or the buzzer stops sounding, the short is cleared.
Refer to the above wiring diagram link in spooktn post #4 for your vehicle, to trace wire color codes & let us know how it goes.