Mk 3 rear brake switch

I found my rear caliper to be quite stuck, so i removed it and manually pushed the piston(s) back out a bit-( it seemed to be both pads are hydrauliclly active), put it back on and flushed the tank with about 10 ounces of DOT3 ran thru it, a little orange/yellow at first, then eventually clear, was in the little plastic pipe i had plugged onto the bleeder- now, as then, the brake light stays on--does that pressure activated switch get plugged and hold itself in? the calipers releasing satisfactorily now since the flushing
i tried to make up a tool to spin out the caliper disc to deep clean the caliper, but that will require the real deal factory tool ,(also to screw in a stainless version) its not a left hand thread is it?

If the brake is off, then the brake light should go out, unless there's some pressure trapped inside the hydraulic system, in which case the brake should be dragging? I can only suggest that you remove the switch and check if the small pressure hole in the switch is plugged up? Otherwise there isn't much that can be done, only replace the switch with a new one.

The caliper plug is normal R/H thread.

With the key on apply the brake and release. Then crack open the bleeder. If the light goes out your master cylinder is not releasing fully. If it does not, the switch needs to be replaced.

On a Mk3 you must carefully reassemble the rear master cylinder body or you can wind up with the piston not retracting fully.

Since your caliper was corroded enough to be stuck, you master cylinder could need rebuilding also.

You can often help the removal of the caliper blanking plug with a little heat on the caliper body with a blow lamp. No need to get it really hot, just hot enough to just hold with bare hand.


New seals & stainless pistons should male the caliper good for a long while.

Bob.