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Rear brake lights not lighting up

VYY930

VYY930

New member
Hello,

I took the 930 out for a spin today (was actually used yesterday to take the groom to my sisters wedding and was on route back home) anyway, I pulled onto my drive and the guy across the road noticed my brake lights weren't coming on.

I have had a look today at some diagrams and see that the actual circuit looks pretty basic.

I am referring to page 970-64 Electrical Wiring Diagrams of the worshop manual (thinks its a Carrera manual to be honest). The diagram shows a feed from the battery to a couple of "stop light switches". These are located on the brake master cylinder. From here the feed to the brake lights literally go all the way to the light itself.

So, with my trusty meter I tested for 12v on the incoming side of the switches - got 12v, working on my own isnt too easy in this case as I need to watch the rear lights and pressing the pedal etc but I think to myself "no problem" as I can simply bridge the switch out with a piece of wire. This I think would then put a feed to the brake light and light it (ignition on of course).

Hmm, not quite. I did a continuity test from the outgoing side of the switch right back to the offside brake light and that seemed ok.

So, my question is simply why doesnt the light come on? The sidelights, indicators etc all work fine so that proves the "ground point" is good.

I take it that the switches are nothing more than made / broken when the brake pedal is pressed.

I'm going to take another look in a bit when things are slightly darker. At least then I can do all testing on my own AND see the brake lights come on...if they do.

Any help on this one is appreciated. Seems easy but am I missing something.

Chris
 
both of my switches have failed during the time i have had my 930, i have a high level brakelight so can see them in the mirror at night. when first switch blew the lights would come on but only when the pedal is pressed really hard, new switch fixed it.. couple of years later same problem, but second switch blew...maybe both switches have blown at once?
 
Hi,

Thanks for your response.

I have now sorted it out [:)].

Having had 12v going from the front to the back of the car proved the wiring was ok, the bulbs were tested too and were also iliminated. I couldnt understand why I had 12v on the back of the light cluster contact and yet the bulb was not lighting. The drivers side rear light cluster was removed and the wiring checked which was also fine.

So, still baffled I decided to go back to the switches. I tested for 12v on the incoming side of the switch, it was there! Then using a 2 inch piece of wire made a bridge across the wiring connector. Stuffed my meter on to see if I had 12v and didnt. Huh! So, here I am with 12v on one side of a 2 inch piece of wire and not on the other end of it. Moving back to the fuse box I rechecked the fuse and found that the spring contact which holds the fuse in place looked a bit light. Out comes the fuse and I see that both ends of it had been arcing and caused small black rings. A quick adjustment to the spring contact, a reinsertion of the fuse after a clean up and hey presto my lights are working fine again.

So, it appears that as soon as a load was placed on the circuit it would crap out.

I will now go through all the fusebox connections to make sure they have enough spring pressure against each fuse.

Chris
 
ha ha nice avatar Christian!

I took one look at that and instantly had a flash back of me going to my Grans for lunch on a school day - thanks for the trip. [;)]
 
LOL!

Yep, that Pipkins show was something I used to run home from school to watch too. Class act indeed.
 
I had a problem with my headlights once. Mechanics spent ages trying to fix it. New fuses fixed it even though the old ones were not blown, it was the contact to the fuse box & the fuse. I suggest you replace the fuses with new ones. I hate to think how much it cost me for those mechanics trying to fix my fault for that sake of a few fuses.
 
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