Brake Light Problem

[Iain]

Can anyone explain to me why my rear brake lights are constantly on when I turn on the ignition, is it something to do with the PDWA switch into which I've recently put new o rings and the positioning of the shuttle valve or something to do with the way I've bled the system? I know I've seen something on this subject somewhere before but can I find it when I need it!!
Any ideas or advice would be appreciated.
Iain

[Ian Durrant]

Hi Iain,

The brake lights are operated by a switch on the brake pedal itself. I'd start trouble shooting there. It might be that your pedal is a little low (not returning properly) or the switch may have fallen apart inside. IIRC there is some adjustment on the switch too.

[Danny]

My bet would be a faulty brake light switch, i have seen this a few times. eventually it can cause overheating of the switch and the insides can melt.

Danny

[Iain]

Thanks guys, both of the above would make some sense as I also replaced the master cylinder recently so I think I'll start by checking all is back together properly.

[StagnJag]

If, in the process of changing the master cylinder you happened to have lifted the brake pedal, you may well have bent the bracket that the brake light switch attaches to. It pushes onto the front of the pedal stem and thus the circuit is made when the pedal is pressed and the plunger extends. If you lift the pedal, the bracket bends and the switch plunger is permanently extended until you bend the bracket back. (BTDT)!

Rgds

Dave

[ukbiggles]

Had the same problem when I replaced the master cylinder on mine. When all connected up again, the pedal didn't quite come as high off the floor, so the plunger in the switch remained extended, and hence the lights stayed on. Just had to bend the braket containing the switch to make if work again. Cheap fix!!

Gord

[Ian Durrant]

Just had to bend the braket containing the switch to make if work again. Cheap fix!!

Gord

See, I knew it was adjustable

[Moraystag]

Had the same last summer after master cylinder replacement, the switch at the brake pedal was being constantly pressed. 2 seconds to sort it out and readjust.
Simplest of simplest thing to do but I did scratch my head for a while LOL
Mike

[Iain]

Got to be one of the easiest fixes ever! Thanks to all of you.