Stop lights not working

mike rigg

Member
Hi just got my P6 v8 auto back from the mot station. It failed because of rear brakes not working efficiently plus poor handbrake and no stop lights.
I've booked it into the garage to get things sorted but wondering why the stop lights aren't working. Should I get get a new switch and if so where is it located. Or is the lack of stop lights associated with the poor rear brakes, right hand side only showed 17 kgf whilst right showed 87kgf.
Maybe I should just look at replacing both calipers, are they readily available?
 
The brake light switch is on the driver's side (RHD) inner wing, down in front of the servo. They are prone to failure. Remove the 2 wires and join them together and the brake lights should come on if the switch is faulty. It won't be due to the rear brake problems. It sounds as though the RH caliper is mainly at fault but a visual inspection of both will tell more. Calipers are readily available, but if they're not leaking it may just need the mechanical side repairing. Worthwhile resealing at the same time though.
 
As mentioned check that both brake light bulbs are OK before changing the switch . They seem to often go in pairs.
 
Here is the brake readings from my p6 I MOT last month.
Note the handbrake efficiency is as good as the foot brake when they are working / set up correctly.20190123_084810.jpg
 
The brake light switch is on the driver's side (RHD) inner wing, down in front of the servo. They are prone to failure. Remove the 2 wires and join them together and the brake lights should come on if the switch is faulty. It won't be due to the rear brake problems. It sounds as though the RH caliper is mainly at fault but a visual inspection of both will tell more. Calipers are readily available, but if they're not leaking it may just need the mechanical side repairing. Worthwhile resealing at the same time though.
 
Hi Harvey, can't seem to attach photo. Is it on the bottom of the tee piece which leads into the servo. There are two connections one has two wires one has one wire. If I have to replace it do I just undo the nut, my concern is will brake fluid run out. Cheers mike
 
That's it, have your new switch to hand, remove the old one immediately putting a finger over the hole, then swap the switches and quickly screw the new one in. You shouldn't need to bleed, but if you feel that you must you can just bleed through the "out" pipe fitting on the connector.

PS that switch does seem to be oriented differently to how I remember them. Yours is downwards, I remember them as horizontal.
 
Last edited:
Harvey, not getting anything. Tried measuring voltage and current bur nothing across the wires. I also noticed no reversing lights so thought it was a fuse but they all seem ok, in the fuse board. Any ideas or it's going to go to auto electrician.
 
Hi, checked fuses again, and one had blown, replaced and now have reversing lights so will check brake light switch again, tomorrow. If that is ok any suggestions
 
That's it, have your new switch to hand, remove the old one immediately putting a finger over the hole, then swap the switches and quickly screw the new one in. You shouldn't need to bleed, but if you feel that you must you can just bleed through the "out" pipe fitting on the connector.

PS that switch does seem to be oriented differently to how I remember them. Yours is downwards, I remember them as horizontal.

I see replacement pipes there, I'll bet that's a restorer's custom configuration there. I agree, the switch should be horizontal.

Yours
Vern
 
It should work in any position, but being in the bottom it's going to slowly collect any sludge & debris that settles out so it's not the ideal position.

Yours
Vern
 
All my parts catalogs show the switch either on top or facing forward on single circuit brakes. But the NADA twin circuit system (which has two switches) has one of them mounted on the bottom, so obviously it was done by the factory at times.

Yours
Vern
 
Back
Top