As soon as I hook up my battery, all 3 of the rear brake lights come on and so does the light in the idiot cluster. The only way I can get them to turn off is to unplug the two wire connector on the switch above the pedal. If i unhook the single wire on the switch, they stay lit. The same thing happens by unplugging the single wire on the e-brake. I also noticed the switch above the pedal is getting kind of warm. It is a NA -> 5spd swap if it matters. Any ideas?

 

this one time i put a FB together and i plugged the brake lights into the cruise control cancel switch and then cruise control into the brake light switch....

i looked at the diagram, the actual brake lights get switched by the switch directly.

the warning light is totally separate, and is triggered by low brake fluid and or the ebrake switch.

 

ive got a 2nd identical model sitting in my driveway. i checked and it has a green & green/white wire going to the brake switch. it is the same as the car i am working on. so i don't think i got it mixed up.

 

S4 or S5? On an S4 the Green/White wire has constant power and White/Green has voltage when the brake pedal is depressed. It is possible the Brake Switch always passes voltage from one wire to the other (faulty/stuck closed contact in switch). The other possibility is the W/G wire is receiving voltage from another source. So disconnect the Brake Switch plug and check which one has voltage. Also, not sure if it is possible to reverse the plug on the switch as already suggested as it's not just relevant if the wires are the same color,but more importantly whether the wire w/the voltage is feeding the switch or coming out of the switch. If the voltage wire was connected to the output side of the switch then the brake lights would light up constantly.

 

its s5...i get battery voltage on the g/w wire. the plug will only go onto the switch one way. i do have a spare switch on another car i could try if that is the culprit.

 

Then the Green wire should not have voltage when plugged into the switch. If it doesn't have voltage when not plugged into the switch, but does when plugged in then the switch must be the cause. The Green wire is connected to various components but if this wire does not have voltage unplugged then it should not when plugged in either.

W/the switch unplugged, you could run a jumper wire from G/W to where it connects to the switch then take a reading from the other terminal on the switch w/o the brake depressed and check for voltage on the terminal that the Green wire would run to. This will tell you of the functionality of the switch.

 

im getting voltage on the green wire only when plugged into the switch...gonna take the spare switch off my parts car and try it.

 

replaced the switch and it's working now! thanks a lot, i really appreciate it. one more step to getting this car back on the road