How to change the BRAKE LIGHT SWITCH

I've got 53,000 miles out of mine so that's good then   Just in case anyone else is looking here the symptoms are the glow plug light flashing and if you have the MFC (Multi funtion computer) you get a scary 'Engine Workshop' message as well. 

Might as well make it a 'How to do'    It's an easy job on a T5 once you know how, but if you don't it's easy to wreck your new switch. 

 

Removal  

 

First take out the six or so torx 20 screws on the plastic panel under the driver's feet.  The switch is then easily seen above the brake pedal.  With the ignition off, just grab it, turn it anti-clockwise and pull it out from its bayonet fitting with the wiring attached.  Then, squeeze the two prongs on each side of the wiring plug and pull it free.

 

Fitting

 

It's really easy to break these unless you know how they work.  The switch has the usual spring-loaded plunger.  Plunger out = brake lights on,  Plunger in = brakes lights off.

 

However, VW TDI switches have an internal ratchet which needs to be set and then locked.   I don't know why this is adjustment is needed but probably so the same switch can fit different VW models with different pedal travel.   

 

The ratchet needs to be set for length first so-  Engage the switch in the hole then make sure that the plunger just touches the brake pedal- don't turn the switch at this point, just stick it in the hole and allow the plunger ratchet to shorten (click click click) until it just contacts the pedal.  Now comes the critical bit- once you turn the switch clockwise to lock it into its bayonet fitting this also locks the ratchet to the plunger length (from the pedal) you have chosen.  If you mess with ratchet from now on you will probably strip the internal plastic teeth.  Click the wires back on and that's it.   

 

If you had the the glow plug light on the dash flashing and/or any other dash warnings, a few presses of the brake pedal with the engine running should clear them if the switch has been fitted correctly.  Don't forget to check that the brake lights go on and off as they should.  Make sure that the brake pedal needs to be pressed slightly before the brake lights come on.  If it's too 'hair trigger' and the brake lights come on with barely the weight of your foot they may flicker on when you are driving leading to the engine cutting to idle as you are driving!  I think you should be ok to reset the length of the plunger if you need to but only with the switch in your hand ie disengaged from it's bayonet fitting.    

 

This description is 'warts and all' and actually it will only take you a maximum of 30 minutes (assuming you are a complete duffer) to do this simple job.   

 

I'm not much of a fan of aftermarket switches/sensors but I paid less than £7 for mine today and surely it can't be worse than the original