09 Passat TDI rear brake lights stay on

[Hans Senior]

Hi all

A mate of mine is a VW mechanic here and is currently stuck with a 09 Passat 2.0 TDI where the rear brake lights stay on permanently.

Diagnostics computer shows a faulty brake switch, this has been disconnected / removed (to be replaced with a new switch still), the problem still remains, parking brake seems to be functioning correctly still, brake lights still on even though EPB disengaged.

The car was presumably in an accident before and that there is one other fault code (05712) showing up on the diagnostic scan, databus to instrument cluster. The car does cut out intermittently when idling. Fault codes have been erased, but show up again when a diagnostics test is done.

Numerous warning lights on the dash stay lit up when the car is started.

I think the main issue to be solved for now is the brake lights staying on permanently.

Ideas / advice please

Thanks

[RichardSEL]

You say numerous lights stay on the dash. Soas we can see what lights they are, or more importantly what faults are being reported by the control modules in your car, get a diagnostics scan done with a tool that produces a text output -- VCDS (Vag Com Diagnostic System) will do it if there's anyone there with that. Or a VW main agent or indie shop will have VAS 6052 but you'll have to pay for that. Usually half an hour but over here many dealers are charging an hour

Try disconnecting battery, fully re-charging it (overnight if using a small trickle charger). Short the two battery leads together before re-connecting to see whether your battery is no longer giving enough current. These electronic modules are very susceptable to lower battery volts, especially on switch on of IGN of a TDi when the glow plugs are operating. And then when starter motor is taking most load.

Let us know how you get on? Otherwise too general a description of fault scenario to get into too much depth.
What accident? To what part of car?

[Hans Senior]

Hi, thanks for the reply.

Guess we could try the dealer. Accident - not known, but one can see the airbag had popped out previously and the hole has just been patched up again, the front bumper was fitted badly again, not sure if the airbag was put back, seems the customer does not have much money to maintain his car. Engine light, steering light, parking brake light etc. remain on whilst driving.

[RichardSEL]

Sounds like it's been tarted up soas it runs. And who know what's been fudged to make it just run? Undoing all that sounds like grief

Good luck! Totsiens

[Hans Senior]

Yip. my friend not really keen on working on the car further, would take too long, he has a business to run, customer is impatient and probably lacking funds.

[Anis7867]

Hi guys.. I have a Passat Estate 2012 1.6TDI... I have a fault with the break lights they stay on all the time as soon as you put the key in... we replaced the break switch.. it does nothing.. even when you disconnect the switch the break light still stay on... I was told replace the body control module.. so we replaced that and still nothing, we change the ECU and still nothing... I have had the car a year I never had a single problem with it until the battery failed and we replaced the battery with a agm genuine vw battery... (could this be related to this fault ?) please guys your help is needed.

[Crasher]

Disconnect the clutch master cylinder Hall sender on the side of the cylinder in the engine bay, low down and in line with the clutch pedal.