Brake Light Confusion - Urgent Help Needed

[ferguscawley]

Got the warning lgihts on the dash of my 97 Sharan TDi showing that neither of my brake lights were working. Sure enough, they were not, including the high level brake light.

 

Checked the fuse. Ok

Checked the brake switch - OK (goes open circuit when brake pedal is pushed)

Checked the loom that goes through to the tailgate via the rubber bellows thing - OK

 

 

Anyone got any ideas why all 3 should suddenly fail ?

 

I have looked thought the ETKA cd antil I almost went blind. No help there.

 

Is there an interposing relay for the brake lights ?. If so, where is it and what number is it ?

 

Any help at all would be appreciated. I feel nervous driving the car with my kids on board without having brake lights.

 

Thanks

 

Ferg

[Guest vr6galaxy]

Checked the brake switch - OK (goes open circuit when brake pedal is pushed)

No! AFAIK it should go closed circuit and make the circuit, try unpluging it and shorting out the pins on the plug? the brake lights should then come on?

the light failure unit relies on you pressing the brake pedal and making the circuit in order to test the brake light bulbs

you may be testing the cruise control switch? these goes open circiut when operated IIRC?

[ferguscawley]

VR6 - thanks for your reply - much appreciated !

 

I don't have cruise control on my car so it's definitely the brake switch I was testing- a blue 2 pin switch above the brake pedal.

The switch definitely goes open circuit when the pedal is depressed. I tried unplugging it and shorting the pins also - no difference - the lights still don't work and the warning lights on the dash stay on. Thats what leads me to think there is either another inline fuse or relay somewhere between the brake switch 'unit' and the rear lights.

 

As an aside, a friend of mine borrowed my trailer last week and damaged the lights on the lighting board. I have used the trailer since so there possibly may be a short somewhere in the trailer lighting circuit that could have caused a fuse to blow. However, the main fuse (number 20 as I recall) is still OK. If there is another inline fuse or relay (although I cannot see why there should be), it must have a lower current rating than the primary fuse.

 

I have checked the earths at both tail-light clusters and they are sound. There is no evidence of corrosion or anything simple that could be causing it. Bulbs and bulb holders also perfect.

 

The power supply to the right rear brake light is via a red/black wire. This is dead - no voltage.

 

This thing is driving me mad. I hate vehicle electrics with a passion - simple circuits but finding the f**king wires or a decent wiring diagram is a nightmare. The Haynes manual is almost useless electrically.

 

Any other ideas ?.

[Topbloke]

first to check is, is there any voltage at the switch connector, if answer yes then there is a problem between switch connector and rear lights, if no voltage then there is a fuse blown between switch and fuse board , if you are desparate to use the vehicle you could substitute a feed to the switch from the fuseboard , i am unsure if there is another fuse in the system, there are some fuses under passenger seat (the area that fills with water) that supply the rear but i do not think that these work the lights, as an also there are some times two switches fitted even though you dont have cruise

[ferguscawley]

Thanks guys

 

Maybe there is another switch that I haven't seen yet - I'll have another look tomorrow when the rain has stopped pissing down :D

 

I did see another one up there but it seemed to be activated by the clutch pedal (I have no idea what it's purpose is though).

 

I'll let you know what I find.

 

All the best

 

Ferg

[Guest vr6galaxy]

Should be a Red/Yellow supply from the fuse (F20 10A) and a Black/Red out to the brake lights, try sticking a temp supply up the Black/Red and see the lights operate?

clutch pedal switch will be for the cruise control, this switch will be a normally closed type, although you havent got it fitted most of the kit to operate it is most likely fitted, as yours is a TDI all you need is the control stalk and it switching on via Vagcom!

[Masked Marauder]

 

I don't have cruise control on my car so it's definitely the brake switch I was testing- a blue 2 pin switch above the brake pedal.

Your car is still wired for cruise control, only the stalk is missing. Are you sure the switch has two connectors as some have 3 and are a dual purpose switch.

 

If it only has two wires then make sure there is not another switch behind it.

[ferguscawley]

 

I don't have cruise control on my car so it's definitely the brake switch I was testing- a blue 2 pin switch above the brake pedal.

Your car is still wired for cruise control, only the stalk is missing. Are you sure the switch has two connectors as some have 3 and are a dual purpose switch.

 

If it only has two wires then make sure there is not another switch behind it.

Yep -definitely only 2 wires - very small wires too - I reckon 0.5mm cross sectional area - probably too small to be switching power directly to brake lights. It must be part of the cruise control system alright.

 

The more I think about it, the more I am convinced there must be another switch hidden up there somewhere for the brake lights only.

 

I'll have another look tomorrow.

 

BTW, where do I get a stalk for the cruise control from ? Is it easy to fit ?

 

Thanks

 

ferg

[Masked Marauder]

The cruise stalk is very easy to fit. Two screws.

 

Then you turn on on the ECU if required (some do, some don't) and you have CC

 

The stalks are rare though, I got mine from a breakers yard. They had about 15 Galaxy/Sharans/Alhambras in and only one stalk.

[ferguscawley]

SUCCESS !!!!! B)

 

Sure enough, above the blue switch (cruise control) was a black brake switch (it was impossible to see with the blue switch in it's way). Got the part number and drove to the VW dealer and got a new switch for

[Guest vr6galaxy]

result B) it's nice to hear when someone has fixed/found the fault :D

[VeeDub Nutter]

Now I just need to find a cheap cruise-Control stalk somewhere !

If your very lucky a scrappy will have one, if not, you won't get much change from