'92 740 turbo wagon brake light switch repair

rberner · Post by **rberner** » 31 Aug 2008, 00:58

I've been told replacing the brake light switch should solve no brake light problem. I can get the part for $25 but they say it takes an hour and a half to replace it (which is about $90). Can you show me how to do this myself? I have 234,800 miles on my car.

Post by **billofdurham** » 31 Aug 2008, 11:43

I take it that repair time includes a lunch break.

The brake light switch is mounted above the brake pedal. To get to it remove the trim under the dash on the driver's side. Look up to where the brake pedal pivots on the bar and you will see the switch. Disconnect the wiring, undo the locknut and unscrew the switch.

When fitting the switch screw it in so that it operates after 8 to 14mm (0.3 to 0.5ins) movement of the brake pedal. Reconnect the wires and tighten the locknut. Check for correct operation and replace the trim.

Who said you need a new switch? Have you checked for 12v at the switch using a voltmeter or a test lamp?

Bill.

rberner · Post by **rberner** » 02 Sep 2008, 23:19

Your reply is why I love asking questions about doing work myself. It was Radial Tire where I get my tires and have had brake work done. My Volvo mechanic in Sacramento, CA, when making an apt. for work that isn't an emergency, seems to avg. 2 weeks away so I've gone to Radial Tire for brakes in the past and when I went in to have a new rim put on (hit a large rock in Cache Creek Canyon), I said that I had no brake lights and had no bulb indicator light and the fuse was good, he said it could be the brake light switch which is just under the brake pedal. Then as I was leaving, knowing I could get the switch for $25 (used), asked what they would charge to replace it, he had his brake guy look at it. He said he had no way of testing it, but that it would probably take an hour and a half, which would be about $90 - so I said I'd probably be back next week end. I hate driving with no brake lights, but decided to wait for a reply from you before going back to have them replace it. So, you mention testing for 12v at the switch-I guess it can be tested first, huh?

Post by **billofdurham** » 03 Sep 2008, 12:54

Yes it can be tested - without removing it.

Take out the trim under the dash so you can see the switch. There will be two wires connected to it - Green/Yellow from fuse #4 and Yellow or Yellow/Brown which goes off to the ABS, cruise control and bulb failure sensor.

The Green/Yellow should be live at all times (does not need you to switch on the ignition). Using a voltmeter or a test lamp check that you have 12 volts at that wire. The other wire is only live when the switch is activated. Again, with the voltmeter or test lamp, check for 12 volts at that wire when you press the brake pedal.

As I said the lead in should be live at all times but if you do not get a reading there switch on the ignition in case a previous owner has altered the wiring. It does happen.

Bill.