1964 brakes lights will not work

[Mike Yager]

It appears I have a short in the brake light circuit of my '64. The brake light circuit also works the courtesy, clock and radio light. When I put a new fuse in, everything is fine until I step on the brakes. The fuse will immediately blow.

There are two wires in and out of the brake light switch. One is black with a white stripe and the other is black with an orange stripe. I assume one is power in and the other is power out to the brake light. It was difficult to determine which was which from the wiring diagram. Does anyone know? I recently had my pedal assembly out of the car to replace the clutch pin. A visual inspection of the wires coming out of the switch does not show any breaks or bare wires, at last for the small portion that is visible but I suspect I might have damaged something in the removal/replacement of the pedal assembly. The turn signals and tail lights work fine.

Does anyone have any suggestions as to where to start checking? I certainly have long enough leads to reach from the switch to the tail lights so I can check the continuity of the line to the lights.

If I find a break in a long section such as back to the brake lights, is the best method of repair to just replace the entire section of wire?

Thanks.

[Wayne W.]

Re: 1964 brakes lights will not work

Orange stripes always indicate hot. First disconect the rear body connector behind the LH kick panel and recheck. This will isolate the problem front to rear. If it turns out to be rear, look at the bulbs and sockets. 95% of the problems will be there.

[Jack H.]

Remote....

chance you've got a problem with the radio. Radio-waz up??????

There's an interference capacitor mounted to the brake light switch. It's intended to thwart surge current flow when the brake lamps turn on (popping noise audible in the radio). Early mid-year cars mounted the capacitor in one topology (if memory serves, in series across the brake lamp switch) while later MY cars mounted the capacitor in parallel to ground across the switch.

Idea is, voltage across a capacitor can NOT change instantaneously, so when the the switch closes the voltage (and resultant current flow to the lamp filaments) 'ramps' up gradually (gradually in electrical terms--compared to the speed of light) and this thwarts the radio interference noise component(s).

If your brake light radio interference cap is shot, the lead wire is making inadvertant contact to ground, Etc. the symptoms you mention WILL result. Diagnostic fix is to completely remove the RF cap and see if problem(s) go away. If so, you found the failure mode culprit. If not, the problem lies in downstream wiring and/or corrosion inside the socket(s) of the tail lamp(s) themselves. Good luck!

[Michael H.]

Re: 1964 brakes lights will not work

Hey Mike -

I had a similar problem. The brake light circuit is shared by the rear turn signal circuits - probably because GM saved a whopping $0.14/vehicle that way. When you step on the brake, you are actually closing both rear turn signal circuits simultaneously and bypassing the blinker. Anyway, If you check the wiring diagram of the turn signal switch, you'll find that the brake lights pass through the turn signal switch. I took the wiring diagram from my 1963 (should be very similar to 1964) and sketched out a separate wiring diagram for just the brake light and turn signal circuits. If you want send me an e-mail (mghaluska@aol.com) and I will e-mail you a copy of the diagram. At any rate, the brake light problem was due to a faulty turn signal switch.

[Mike Yager]

Re: 1964 brakes lights will not work

Mike, Wayne and Jack:

Thank you for your responses. It gives me a good place to start tracking the problem. I did not realize the brake light circuit went through the turn signals. I will take a look at this first. I had dropped the steering column to remove and work on the pedal assembly. The problem seemed to begin after that. I am wondering if I might have pinched a wire when putting the steering column bracket back on.

Mike, I may take you up on your offer based upon what I find.

Thanks again.

Mike

[Mike Yager]

Re: 1964 brakes lights will not work

Found the problem. After determining the wiring was good to the rear lights, I pulled the steering column bracket and clamp out so I could get a good look under the dash. One of the wires that ran to the brake pedal switch and one in the bundle to the turn signal had enough wear to show copper wire. I may have done this while tightening things back while repairing the clutch pin.

Anyway, put some electrical tape on the problem areas and I am now back in business.

Thanks for the help.

Mike

[Michael H.]

Re: 1964 brakes lights will not work

I thought that the turn signal switch had something to do with the problem. Until I unravelled that wiring diagram, I would have never guessed that the brake light circuit went through the turn signal switch.