Malfunction in Brake Lights.... grrr

[Cosmic88]

This has ben a VERY frustrating problem. I shall lay out all the steps I took to find the fault so as to narrow down the possibilities.

Prob- Brake lights do not illuminate when pedal is depressed... the bulbs DO work when connected to 12v supply on both parking light setting and brighter brake setting. Contacts are clean, sockets are making good contact with bulbs. Turn signals both work, and parking lights (both upper and lower light sockets) illuminate when switched on at instrument panel.

1. checked bulbs (L & R) - both working fine.
2. Checked socket contacts - both working fine,
3. wires leading to both sockets in tact and good connections / good ground.
4. 12 ish volts at lead to brake switch on hydraulic brake line junction. When brake bedal is released there is no current... 12v + detected when pedal is depressed.
5. disconnected hot lead to brake light switch and jumped to bulb with good result... then reconnected hot wire to switch and jumped output wire from switch to bulb (and ground) with no illumination. ???????

How could I detect a voltage coming through the switch and yet when the bulb is connected to it get no light?

WTH? that last "H" has an E and a pair of double hockey sticks with it.

[JimCT]

test lamp

ues a test lamp and not a multimeter to check voltage, I have been there and the meter will show 12V but if you put any load on the circuit it fails. Dirty contacts or the like.

[Jeff Aronson]

Sounds like you may have a bad brake light switch; if you can get the lights to illuminate by bypassing the switch, and know that that the wiring from the switch to the bulbs is good, then the problem would seem to be within the switch itself.

Jeff

[greenmeanie]

ues a test lamp and not a multimeter to check voltage, I have been there and the meter will show 12V but if you put any load on the circuit it fails. Dirty contacts or the like.

I'd second the dirty contacts. I had this exact problem on my 101. It has a rather cheap and nasty reed switch operating on the pedal itself and eventually I had to take it apart and clean everything inside. Never a problem since.

[Cosmic88]

Well huh...

Turns out to have simply been a bad brake switch ( the one located at the hydraulic junction for brake lines). The output voltage turned out to be about 9.5 v.

traced every connection with a voltmeter and test lead / test lamp.

Thanks for the tips.