78 no brake lights
Thread Starter
4th Gear
Joined: May 2014
Posts: 4
Likes: 0
78 no brake lights
hello all. i know i have posted this before but i am at my whits end. all turn signals work. all driving lights for night driving work when turned on by the light switch. new brake light switch. all new and working fuses. i have the 12 volts at the brake light sockets and yes the bulbs are in correctly and the correct bulbs. have full continuty to all circuits that apply. but the lights just will not light up when pedal applied. all new hazard and turn signal flashers. by all logic they should light up but will not. i am lost. two pieces of tape away from hanging for sale sign in this pile of fiberglass.
Advanced
Joined: Mar 2014
Posts: 73
Likes: 0
Going to add the same.
Check your power you have 12V good.
Now check the ground you want 0 all the time. It show millivolts that's fine but you basically want a 0 V reading.
If you have any voltage on the ground with the brakes applied you have a bad ground.
Really the only thing left.
Remember being a kid setting up the little light bulb battery and 2 wires.
Same idea the power has to make it back to the battery , if it cannot it will not light.
Sure you have the right light bulbs? Single filament will not light tail and brake.
Check your power you have 12V good.
Now check the ground you want 0 all the time. It show millivolts that's fine but you basically want a 0 V reading.
If you have any voltage on the ground with the brakes applied you have a bad ground.
Really the only thing left.
Remember being a kid setting up the little light bulb battery and 2 wires.
Same idea the power has to make it back to the battery , if it cannot it will not light.
Sure you have the right light bulbs? Single filament will not light tail and brake.
Drifting
Joined: Dec 2002
Posts: 1,946
Likes: 28
From: Long Beach CA
You say there is 12V at the socket. On which contact? There are two contacts in the center of each rear light socket. One is for the taillight filament, and the other is for the brake light filament. Have you checked for voltage on the contacts with the headlight switch OFF and someone depressing the brake pedal? You should have 12V on one contact in each socket under that condition. If not, then troubleshoot forward toward the turn signal switch. If voltage OK, then there is a grounding problem.
