Porsche Enthusiasts Club Forum

Hi All

Brake lights gone ...any ideas ??? Brake lights been playing up lately, now lost them completely and its driving me nuts as to why...
Using my Snap-On probe.... Ignition on....I have 12 volts to one side of switch...activate switch by pushing down pedal, which then makes other terminal on switch go red (12 volts again).... so switch is working... and power going from one side to other.... BUT it aint getting to the back of the car, as no brake lights....ggrrrr....fuse (number 4 is fine but changed it anyway) still not working,,,, any ideas ????

All the best Brett

Hi Brett

If you're certain the fuseholder connections are clean, then I have couple of suggestions:

My S4 has bulb control computer attached to left side of passenger parcel shelf. If this is unplugged brake lights won't function. I'm not certain if S2 has module in same position, and you may have removed shelf to make room for nitrous bottles!

Check connectors behind rear tool tray cover. This is where power from front is fed to rear lights.

If neither suggestion works then could be issue with switches on master cylinder, or interconnect wire dislodged at rear of central etec panel.

Adrian

Hi ADRIAN

Interesting, not sure IF i have a bulb control module ....have you got a pic of it ?

It certainly could be a problem behnd the tool tray as I have LOTS of my wiring for Nitrous etc back there...problem is WHICH wires to test back there ? any ideas as to wiring colour etc ?

I will ring Paul A tomorrow, to see if he has any bright ideas....wish I was nearer Stroud lol.... I bet he could fix it in 2 mins...

All the best Brett

Sorry Brett no photo but if you've got it you can't miss it - black plastic module mounted to door end of passenger shelf, and connects via big multiway plug.

I can check wiring diagrams at weekend to see which plugs you're looking for at rear.

Hi Adrian

Many thanks, I think I have got a black module hanging down near wing side of passenger shelf (not fixed as no shelf that side any more)

Not sure what to check on it....lol

Will not be able to check this all until Sunday afternoon (because of work) so any more information would be hugely appreciated...

All the best Brett

Stupid question, but have you tried the bulbs, or cleaned the bulb holders?

G

Hi G

They were ok , no corrosion a couple of months ago.....but will check..

All the best Brett

If module hanging down and no shelf then very likely that is bulb unit. The brake light power routes from CE via that unit.

Should have multiway plug and big, chunky pin terminals. If plug attached may have been pulled out slightly if module not supported by shelf. If no plug just feel around for it nearby. Should be easy access if shelf missing. Never heard single instance of bulb module failure, so very likely simple plug problem if it's hanging free as you describe. If it is that then after sorting just zip tie the cables to something convenient so no stress on them.

Originally you said problem intermittent, so may be just loose plug. When it fails do you get brake light warning on dash?

Hi Adrian

This really helpful, will look at plug tomorrow... no warnings on dash... just no brake lights at back....

Tried Paul but no answer....he may be racing though, I will be able to speak to him on Monday now that Jude (his wife) is answering phone weekdays....but hopefully will be fixed by then.. lol

All the best Brett

Hi All

Well I found the problem, I think....lol

Thanks to Adrian I had a very close look at the bulb control module....

Took it apart...i.e unplugged it and the thick round pins were a little grotty, so cleaned them up with wet/dry....

Still didnt work...

Then prised the cap off the top and found a wire broken to a brown wire which the little picture on the side of the module says 21 watts for that pin...which is brake lights ...

So I think hooray, found it... get my Snap-On soldering iron out ...(gas one) fill it up.... then find im out of solder lol....

Solder on broken joint is 30 years old so will do it on Tuesday when at work with nice fresh solder...

Hopefully i might have some brake lights then ....lol

So thanks Adrian

The wierd thing is that even with the broken wire there is still 12 volts at the switch at pedal but it just is NOT getting to the back,,, so I must assume that the power goes FROM the pedal switch TO the module ,,,then TO the back....i think ...lol.......and no warning lights on dash either...


Next instalment on Tues lol

All the best Brett

Great investigative diagnostic Dr. Brett...

It's a great feeling isn't it?

Hi

Yup but mainly thanks to Adrian to be honest

All the best Brett

Great that you may have found the problem Brett.

Yes you are correct - bulb module is "last stop" for power before it's fed back to lights at rear.

Hi All

YAYYYYYYYY,,,finally have brake lights....

Long story on cure but basically there were two problems... lol

One was the broken brown wire in the top of the bulb control module...soldered that and that bit was fine, but still no brake lights at rear....

So rang Paul A and he talked me through testing every connection and fuse and connector on fuse board... lol

So we finally got to...it SHOULD be working assuming a good 12 volt feed at the pedal switch.....

I said ... its got a red light on my Snap-On probe....

Paul said..... hmmm... that doesnt mean its got a GOOD 12 volt feed.....

He said... try running a separate 12 volt wire from my Nitrous fuse board....

So did that, attached a new terminal and voila.... all working....

I still cannot quite figure out why the old wire (which comes from fuse 4) would light my probe but not have enough ooommmpph to run the brake lights...lol

But Paul was absolutely spot on and spent around 40 minutes on the phone with me running through all the testing.....

Amazing service from him as usual

I am so relieved they are working as its REALLY annoying even though its a small thing lol...

Thanks to Paul and Adrian yet again.....

All the best Brett