Frustrated: Cant fix error code 4340 stop light switch..

[PR36]

Sods law I desperately need to use my car this Friday for a long trip and after changing the brake pads and tran mounts I am now getting constant abs/psm failure warnings with the durametric showing error 4340 stop light switch. I have swapped the brake switch out twice now with a new one and the error still comes back. Would be really grateful if anyone has any ideas to help as I cant get it into the nearest indy (1.5 hours away) till next week which is too late.

[PR36]

?

[cd1957]

Hi What car is and year would help, but as u have changed switch then its something linked to circuit.

Chris

[PR36]

Doh! So busy stressing I forgot the obvious. It's a cayman s 2007. Thanks!

[cd1957]

Hi on a 996 this code throws up

Stop light switch adjustment
Switch faulty
Short to +/ground, open circuit between switch and ABS unit
Control unit faulty

Chris

[PR36]

Many thanks for posting this, I have tested the switches using a continuity test and they all check out. In terms of checking further for a short/ground I am reaching the limits of my diy ability (!) so I just wouldnt know where to start in doing that or what could be the cause. Oh well I think I am edging towards throwing in the towel, why do these cars have to have so much electrical monkey business on them...!

[Steve H]

If you can dig up a wiring diagram for this, post it up and we may be able to help.

[PR36]

OK i managed to find the whole wiring diagram online, here is the brake section:

[Steve H]

I'd start by checking of 12v on the green wire (pin 1) on the switch when the ignition is on. If it has 12v then I'd be looking for the same on pin 4 which should switch off when the pedal is pressed, pin 2 should not have 12v until the pedal is pressed.

I'd be curious to know where the black wire (pin 4) goes to, do you have a link for those diagrams?