Troubleshooting my brake lights

Yes, it's not uncommon for both switches to be bad.

There is a simplified diagram of the switch wiring on this page of my web site:

Easier than jumping at the switches is to find the plastic splice under the hood where the little harness from the switches comes out.

It's also possible that the connections *inside* the rubber boots on the switches are corroded.

Speedy Jim

Hopefully it's just the connections. My oil pressure sending light connection needed a bit of cleaning recently and I know the connection to the horn must be dirty because it's real weak. I'd rather clean some connections than have to replace the brake light switches and probably bleed the brakes. We'll see. At least the weather is decent here right now. Thanks.

I replace the 2 brake light switches on my 1973 VW beetle about every 3 years. On mine, they go out about every 3.3 years. This is about the easiest way:

-disconnect the battery

-drain and remove the fuel tank

-while you're in there, replace the tank outlet finger filter screen and hose.

-might want to paint the tank too.

First rule of electrical T-shooting:

90 percent of all electrical issues are a ground problem.

You may not have a bad ground, but this is something that hasn't been mentioned yet.

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MUADIB®

If A Quiz is Quizzical, What is a test?

The Peacemaking Meeting scheduled for today has been cancelled due to a conflict.

Why would you remove the fuel tank? On a 70 standard bug you can just remove the left front tire and have full access to the master cylinder.

Bad ground? These are the dual element bulbs so if the ground was bad the regular running light side of the bulb wouldn't work. Anyhow, I did clean the contacts already.

However, I didn't just check the elements for the brake side of the bulbs so they could perhaps have gone bad in both bulbs at the same time. Seems unlikely but I know if I discount that possibility, it WILL be what has happened.

Check the bulbs, the obvious things that people usually don't check!!! You also assumed that they were ok. You can also connect a bulb directly to the master cylinder using two wires and hold it on you hand while you brake to test the switch and the bulbs.

Jo=E3o

I would 1; check the bulb. 2; connect a jumper across the wires to the M.C. and I would add a 3 rd brake lite. one that allows you to monitor the system in your rear view mirror. Good Luck ! You can do it.

Yeah, that's what I was saying - if I assume that can't be the problem, it will turn out to be the problem. It's often the little thing you discount while troubleshooting that turns out to be the problem in the end. So I will be checking the bulbs. :)

I was thinking about adding one of those third lights but I need to make a tray for the rear trunk area behind the seat first.

One good thing about this is if I do need to do some wiring I have two different cordless soldering irons that I got as gifts this past Christmas. Maybe a chance to use them.

Following up on this for anyone who wants to know - the bulbs were okay, the connection under the front hood seemed a bit loose, but in the end it was the switches that were bad. I was able to replace them without letting any air bubbles into the brake system (although I still plan on replacing the 36 year old lines this summer with braided steel ones). Also replaced my horn - I thought the connections were just weak again but it would barely chirp so I got a new one that is nice and loud. Never use that anyhow. Maybe I will now.

Thanks for the update - it will be usefull in the future i am sure !

Rich

I also had a bad switch. In my case the lights were always on! I only notice it when I went to the annual inspection (MOT on UK). I had to quickly disconnected one of the switch to pass ;-)

Jo=E3o