Brake Lights do not light up?

pablo45vt · 03-30-2014, 01:22 PM

A while ago I had an issue with the circuit board on my 1971 914-6. Turns out that the board was fine but the voltage regulator was bad. I replaced it but now I have a weird thing with the front driver yellow parking light and the brake lights. The front light will not turn on but the turn signal works. I've checked the bulb and that's not the issue. In addition, the rear tail lights work along with turn signal but when I tap the breaks, no brighten of the lights? Is this a relay problem or a switch I don't know about?

Your advice is appreciated.

Joe

PCA7GGR · 03-30-2014, 03:25 PM

There is a brake light switch under the brake pedal - check it that got knocked out of place (little lever switch that makes contact when the brake pdedal is depressed).

TheCabinetmaker · 03-30-2014, 03:47 PM

the brake light like he said is switched at the pedal, remove the wooden board at the pedals to access it. however you said the brake lights do not brighten. If you mean they glow dimly when headlamps are on, and you expect them to brighten with the brakes, that is not correct, the brake light is a single filament bulb that is either on or off.

the parking lights in front not coming on might be traced to the headlamp switch fault.

you mention a circuit board issue, which circuit board???

where all the lights working fine before the circuit board issue?

pablo45vt · 03-30-2014, 06:09 PM

I'll check the switch under the brakes. What I meant to say is when I depress the brake pedal the rear brake lights do not brighten to signal that I am stopping.

As to the circuit, it's the one in the engine bay, maybe relay board is better terminology. A mechanic I had told me that the whole board was bad. He removed the voltage regulator and removed a blue wire from the large bundle of wires in the plug and directly plug the wire into the spot where the regulator had been. Since it was winter, I didn't peruse it much but did notice that the driving, yellow light on the driver side was out and that it wouldn't signal.

As the snow is melting, I decided to look into this, hoping to get the car ready for spring and summer drives. I discovered his "wiring" and I had also bought a couple of replacement boards from eBay hoping 1 would work. (This is another story, since those boards don't work and have less contacts for one of the cable plug bundles.). So, I pulled the board off to look at it and discovered there was no voltage regulator. I inspected the board and the potting is all in place. I repaired the "wiring" plugged everything back up and the car actually is running even better than when I put it into the garage last fall. Unfortunately this didn't fix the driving light. I discovered the brake light issue today and have no idea if it is related to the board or regulator change or not.

My weakness is wiring. I've looked at the diagrams on this site but they have just confused me. I'd love to know what all of the relays are for on the board. 2 slots are empty on the board in the engine and 1 slot is empty on the board attached to the fuse panel.

I'm not sure my mechanic who did a great job on the engine was too good at wiring either.

Thanks for the advice. I hope to look into the Switch on Tuesday night.

Joe

John Rogers · 03-30-2014, 08:19 PM

Some things to check while you are laying under the dash on your belly looking at the switch are. Fuse #8 which feeds the brake light switch. Make sure it has power and is not open or blown. At the switch, there should be +12 volts with the key on at the black/yellow stripe wire and there are usually two at the hot side. If you have power to the switch, cycle it to see if you get power at the outlet side, +12 volts when pedal is depressed. If all of that is okay, you can check the voltage to the light bulb socket. You can do this by pulling the bulb and checking center connector to ground with brake pedal pushed. Finally you can check the ground for all the lights which are the brown wires and I forget where they run on a '71 but on my '73 they went to a small stud on the inner trunk wall near the lights.

I would suggest using a known good volt meter and check it against the battery to make sure it reads right. I would surely hope you have one, if not, NOW is the time to buy one. It also helps to lay 4 or 5 pillows on the floor to lay on as it helps keep your stomach and chest from getting sore!

pablo45vt · 04-05-2014, 01:16 PM

Thanks for the tips. There was a loose wire at the switch. The brake lights are working. One small notation, my 6 has dual filament brake lights. I did find one bulb that had an issue with 1 filament. Tiny break in it.

Now to start a new thread for the turn signal/driving light. Which the turn signal works but the driving light won't come on. It isn't the bulbs. I measured the voltage at the plug and it doesn't seem to be getting power. When I pulled of the cover, there are 3 wires in it. One is brown(ground), one is black(connected) and one is white (which isn't connected). I don't see anything to connect the white wire on the bulb plate. Any ideas before I tear apart the other side to see what's going in correctly on that side?