The brake lights on my '66 coupe stopped working again. A year ago I replaced the brake switch and it cured the problem but now it's back. I checked the fuse- good. I checked the switch button travel and it operates as it should. Inadvertently I left the battery connected while removing the lower lead from the switch and it sparked against a nearby brace so I'm assuming there's power to that lead. I checked the fuse again after that spark and it was still good. Tail lights work. Maybe it's the switch again. How do I check that? Looking for some advice from someone who has run across this before. Thanks in advance.

 

A couple questions to start with:

1. Do your tailamps light when you turn on the lights?
2. Do your turn signals work?

 

Measure with a voltmeter or test lamp on the two leads coming out of the brake light switch. When the plunger is extended (brake pedal pressed down) BOTH wires should have 12v on them. If only one does the switch is bad. If both have 12v with the brake on, your problem is between that point and the turn signal switch on a white wire. Check the connector on the steering column where all the turn signal connections plug together. Make sure the connector is fully seated and that the white wire is fully inserted in the slots on both sides of the connector.
If your turn signals work and the brake lights don't AND you have 12v on both sides of the brake light switch when brake is on, the only two places it can be are on the white wire connections or inside the turn signal switch.

 

I'll check the switch with a VOM tomorrow. Tail lights and signals work. Thanks.

 

I'm not sure how to do this test. To test with a meter, do I disconnect the 2 connectors from the switch and insert the meter leads into the connectors or do I leave them in the switch just far enough to have room for the leads and operate the pedal? Also there are 2 additional wires that have folded metal tabs that fit over the switch conductors and are held in place by the wire connectors. What are those?

 

Originally, those two wires were attached to a condenser which would eliminate a static "click" on the AM band of the radio when depressing the brake pedal, illuminating the brake lights. Bottom line, when you unplug the brake switch to test it, you can toss those two wires with the flat spades on them.

 

If the brake light switch is disconnected, you should only get 12v on the orange wire (or black/orange stripe on some cars), If you short that wire directly to the white (or black/white stripe on some cars), the brake lights should come on and you'll have12v on both. If you leave it connected and press down the brake pedal, you should have 12v on both wires. If everything else is working, the brake lights will come on when you short the two wires together, thus bypassing or doing the job of the brakelight switch.
The easiest thing to do if you're working alone is place the black meter lead on a good ground, and measure with the red lead on the white wire, when you press the pedal you should have 12v on the white wire, and zero when you release the brake pedal (with the brake light switch fully connected). If that's good, move on up to the turn signal connector on the column and do the same thing on the white wire on both connector sides. Report back what you find.

 

May not help, but when I removed the flag connector for the radio condenser from the brake light switch, I had problems with intermittent brake lights. After a couple hours troubleshooting, I finally removed the plastic connector and squeezed the female contacts to tighten them up on the male lugs of the brake light switch.
Just a thought.

 

If the switch was replaced a year ago and now the brake lights stopped working again my bet would be the Chinese brake switch failed.

To test

Take a short piece of wire. crimp a male spade terminal on each end. unplug the brake switch connector and connect the jumper wire one spade to each of the 2 slots in the brake switch connector.

If the brake lights come on it's a bad switch.

 

Let me see if I've got this right. With the made-up double ended wire, plug both ends of it into both leads that were plugged into the switch. So like a jumper, effectively bypassing the switch. Correct? Lars said the 2 condenser flag ended wires are not in the equation and only for radio noise suppression.

 

You're really trying too hard to make this difficult. Take the part circled in red and it's wires and put them in a drawer somewhere.
Short the two wires together that were plugged on to the end of the brake light switch. (black/orange and black/white) (in some cars solid orange and solid white) You don't have to make anything up, just bend a paper clip and plug it from one wire connector to the other. DO NOT let it touch anything under the dash that is grounded, it has 12v on it even when the key is off. The brake lights should come on, if they do, the brake light switch is bad.
That is NOT the best way to test, the best way is as I described before, measure the voltage to make sure it's on the orange wire coming in from the fuse box. IF it is, measure on the white wire going out of the connector (with the switch connected and the brake pedal pressed down or the switch plunger extended and goes up to the turn signal switch connector on the steering column. If you have 12v on both sides of the white wire in the turn signal connector and the brake lights aren't on, you have a bad turn signal switch. Shorting the two wires at the brake light connector will tell you if the rest of the circuit is working or not, but if they still don't work, you're still going to have to measure where you are losing it anyway.

 

IF your connector has two single wires instead of a connector, just plug the paper clip from one to the other. (orange and white) If the brake lights come on with the paper clip in place, buy a brake light switch. If you decide to measure for voltage, post back where you have voltage and where you don't per my previous descriptions.

 

OK. All the responses tell me what I need to know. I suspect the switch so I'm trying the jumper first. If it isn't the switch, I'll chase it down with the vom. Like everything else, I'll figure it out sooner or later. Thank you to all who responded.

 

GREAT diagram!! Thanks

 

I had that same problem on my 65. It was a combination of a cheap switch and misalignment. If the switch bracket gets bent or the petal arm shifts due to worn bushings etc. it puts a side load on the cheap plastic plunger which eventually causes the switch to fail.

 

It's the switch. I used the wire jumper and the brake lights went on. Junk aftermarket from a reputable auto parts distributor. The switch had very very light usage since I replaced it last year as I hardly drove the car. I'm looking at an Echlin SL169 as a "quality" replacement. Any better alternatives? And thank you again for all who contributed.

 

Glad you found it.

I think most of the Echlin products are fine. You have a wide variety of choices at Rock Auto as well, including Standard Motor Products (which I think owns the Echlin name). Sadly, though, it sounds like these and other reproduction switchgear parts have to almost be treated as consumables these days.

 

Well I have a similar problem but different. My turn signals are not working correctly. Only the right rear one is blinking but not correctly. It acts like it has a short. The left one does not work at all. The brake lights come on but also not correctly. One on each side is bright and one on each side is dim. The parking lights and tail lights all work correctly. I removed the brake light switch and I will test the connectors tomorrow. Any ideas on where to go for the shorts. This is on a 63 with an original unmolested harness that does not have any issues anywhere else.

Thanks
Jay

 

That's not even similar. Your best bet to get answers is to click on "new thread" at the top and start your own thread so that you get readers and answers pertinent to your issues and not all mixed together because people aren't reading the dates of the posts. Sounds like your grounds at the rear bulb assy's and sockets need to be checked. Start a thread if you want specific advice. It won't be the brake light switch.

 

Will do.
Thanks
Jay