brake lights don't work!
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Joined: Feb 2005
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brake lights don't work!
Hey guys,
I'm just about to get my 77 back on the road after 6 months out of commission but I came across a little problem tonight...
All the electronics are working fine, except for the brake lights. The tail lights turn on with the headlights, the blinkers all work, but for some reason when i depress the pedal nothing happens. I tested the switch with my multimeter and it works fine. I did notice, however, that if I hold the button on the brake light switch in, I hear a faint whining sound coming from under the dash somewhere. Does this mean that something isn't grounded?
>Matt>
I'm just about to get my 77 back on the road after 6 months out of commission but I came across a little problem tonight...
All the electronics are working fine, except for the brake lights. The tail lights turn on with the headlights, the blinkers all work, but for some reason when i depress the pedal nothing happens. I tested the switch with my multimeter and it works fine. I did notice, however, that if I hold the button on the brake light switch in, I hear a faint whining sound coming from under the dash somewhere. Does this mean that something isn't grounded?
>Matt>
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Joined: Oct 2006
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Start by checking the brake switch for power. Make sure it's got power to it and the other terminal has power when you make the switch. The brake lights run thru the turn signal switch too. I have seen that go bad- everything will work except the brake lights. I'm thinking the turn/brake lights are the same fuse. Your diagram will allow you to track that. Also, if you have the factory service manual, there's a good troubleshooting tree in that. Shows power feed, fuse, and terminals.
Burning Brakes
Joined: Sep 2008
Posts: 805
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From: Naperville Illinois
Start by checking the brake switch for power. Make sure it's got power to it and the other terminal has power when you make the switch. The brake lights run thru the turn signal switch too. I have seen that go bad- everything will work except the brake lights. I'm thinking the turn/brake lights are the same fuse. Your diagram will allow you to track that. Also, if you have the factory service manual, there's a good troubleshooting tree in that. Shows power feed, fuse, and terminals.
Check the fuses first, but if they're good you can still troubleshoot this yourself. There's a big plastic connector (referred to as the harmonica) at the base of the steering column where the wires from under the dash feed into and return from the turn signal switch. A wiring diagram will help (look up forum member papawana) but you can get by without it. Jumper a hot wire in there and bypass the turn signal, keeping track of what lights up when you power each wire. Make sure your turn signal is centered (off) when you do this. If your brake lights come on, the culprit is the turn signal switch. If not, it's wiring/bulbs/ground...this is what I remember, anyway--I did this last year.
I'm pretty sure every light back there, or at least every circuit, is individually grounded with wires that run to a grounding block. A bad ground has been the source of 3 out of the 4 electrical problems I've had with mine...
Good luck
Last edited by Rally68; Jul 31, 2009 at 09:21 AM.
