'94 940: testing brake light switch

[writer100]

Okay, my brake lights do not light. The fuse passes a continuity test. When I remove a bulb, it does not indicate a bulb out. This points toward the bulb out sensor relay. But first, how do I find and test the brake light switch?

I haven't done a lot of electrical work, so pictures and as much detail as possible would be welcome.

Thanks.

[billofdurham]

The brake lamp switch is mounted on the bracket holding the brake pedal. It is normally open, closing when the brake pedal is depressed. One wire is live and the second becomes live when the switch closes. To test the switch remove the two connectors and, using an ohmmeter, test for continuity at the switch when you press the brake pedal.

Another way to test without an ohmmeter is to remove the two connectors and use a short piece of wire to bridge them. If the brake lights come on the switch is faulty.

940 brake light switch.pdf

(35.48 KiB) Downloaded 706 times

Bill.

[writer100]

Thanks, Bill. It is still too dark to work when I get home from work, so I am waiting for Saturday to perform this test. I will report back.

[writer100]

My brake light test was inconclusive. My switch did not appear as the one you posted.

In any event, I tested the bulbs and tail light circuit boards for continuity; both were okay.

I removed the coin tray and extracted the relay. With the link from brickboard below:

http://www.brickboard.com/RWD/index.htm?id=715116

I tested the relay pins for continuity. It failed two of these tests. So I ordered a new relay from IPD. We will see if this does the trick.

[writer100]

Well, Saturday came, I dropped the relay in, and it did the trick! By the way, this was an aftermarket relay from IPD made by KAE. It was actually German made, unlike the plethora of Chinese made stuff that we are inundated with here.

If I can get the top off the old relay, I might try to solder it to make a back up.

I learned a lot from trouble shooting this.

Thanks, Bill for your prompt help!

[billofdurham]

Thank you for the update. Happy motoring.

Bill.