Brake lights

[k_r_b_]

i have had the glow plug light flash on my dash (2002 golf) when i used vag-com it said
brake switch implausible signal
i dsont understand the acutal problem because if its the brake switch none of the brake lights would come on but i still have the middle light come on but not the side ones
any help please?

[elPaulio]

The obvious check for the lights is to see if the bulbs have blown!

Then I would get into Vag-Com and scroll through the reading blocks until you find the one for brake pedal activation (Forgive the lack of correct tags, long time since I have seen it!) and try the brake pedal to see if Vag-Com acknowledges the pedal working. This should tell you if the switch is faulty.

That's what I would do

Paul

[ky_bren]

The obvious check for the lights is to see if the bulbs have blown!

Then I would get into Vag-Com and scroll through the reading blocks until you find the one for brake pedal activation (Forgive the lack of correct tags, long time since I have seen it!) and try the brake pedal to see if Vag-Com acknowledges the pedal working. This should tell you if the switch is faulty.

That's what I would do

Paul

Iv had a look but cant quite find what bit you mean on the vag com, iv checked the bulbs and they are ok but only middle one works still any ideas im stuck got my mot in 2 weeks

[elPaulio]

Hmm... if the middle light comes on when you push the brake pedal then the switch is ok.

Must be a wiring issue, have you checked that the plugs going into the bulb holders are secure and clean?
Get a multi meter and check for any voltage coming from the wiring when someone pushes the brake pedal!
Check and see if there is a fuse for the brake lights, could be seperate from the middle one being LED's.

I will have a look when I get home and see if I can dig up anything else to try.

Cheers

Paul

[elPaulio]

Hi there,

You could try checking fuse 13 in the fuse box and also Relay 13 in the relay box under the bonnet. This is a "Brake Light Supression Relay" Not sure what that means or what it does, but you could have a look.

The fuse should run all three brake lights so I can't see it being the culprit but worth a look.
Are you getting any other bulbs working in the rear clusters?


Paul

[petercooper]

Some of brake light switches have 4 wires, 2 for outer lamps and other two for abs and centre stop lamp.

Its most likely a faulty brake light switch.


The new brake light switch has to be adjusted correctly before fitting.
So if you are having a go yourself ask the VW dealer if you can have a print out of the fitting instructions.



Hope its of use


Peter Cooper

[chillin_uk]

Im having exaclty the same issues with my 1.9 tdi a4
centre brake light working, brake lights in clusters not working, checked bulb, checked fuse, checked wiring...!!
any help greatly appreciated...mot in couple of weeks so needs sorting a.s.a.p

[elPaulio]

Hi there,

Going by what Peter said, it sounds like your brake switch is faulty.

Check the switch which is above your brake pedal and see that it's switching all four wires. This appears to be the only common point to the outer lights that isn't common to the centre light so it stands to reason it is the fault.

Cheers

Paul

[tornadored7]

Car:

Golf MK4/Bora


Symptoms:

• "Engine Workshop!" on Multi Function display
• Flashing Glowplug light (for a TDI)
• All three brake lights don't respond to brake pedal (either always lit or unlit)
• In my case, the following VAG-COM fault codes;

00526 - Brake Light Switch-F
008 - Implausible Signal - Intermittent

01435 - Brake Pressure Sensor 1 (G201)
008 - Implausible Signal - Intermittent


Commonly due to:

Faulty 4 pin brake light switch.

The 4 Pin Golf MK4/Bora brake light switch (BLS) is a poor quality, badly engineered piece of plastic with cheap metal contacts, (rather than a quality micro-switch, what has happened to VW? ).

This switch definitely puts the breaking into braking .

Internally, the 4 pin BLS contains two seperate switches, which should be activated/decatived in unison. Pins {1,4} (outer pins) connect to one of the internal switches, while pins {2,3} (middle pins) connect to the other internal switch.


Other possibilities (won't necessarily generate a fault code):

• Fuse 13
• Faulty brake light bulbs (12V 21W, G4/Bora top bulbs in rear cluster)
• Bad wiring
• Relay 13 has also been mentioned (but I don't know enough to comment)

Using VAG-COM to diagnose a faulty Brake Light Switch:


1) Start VAG-COM as normal, with an appropriate data lead connected to the diagnosis port, and ignition key turned to illuminate the dash tell tale lights.

2) [Select Control Module] -> click Select
3) [Common Modules] -> click 01 - Engine
4) [Basic Functions] -> click Meas. Blocks - 08
5) [Group] -> Type in 006, then click Go!
6) Read the value in the Bin. Bits Field;

• With the brake pedal not pressed Bin. Bits should read: 000
• With the brake pedal pressed down Bin. Bits should read: 011

With a fully released or fully pressed brake pedal, Bin. Bits values of 010 or 001 indicate a faulty brake light switch.

Aside: Denoting the Bin. Bits field by [b3 b2 b1], then b1 and b2 are actually the state of the 2 seperate internal switches within the BLS (mentioned previously). Hence, 010 or 001 values signify that the internal switches aren't moving in unison, which may (for example) explain the high level brake light operating, but not the side brake lights.


Sourcing a replacement BLS:

Original 4 Pin BLS VW Part numbers:

• 1J0.945.511B
• 1J0.945.511C
• 1J0.945.511D (how faulty were these switches ? )

Replaced by: 1J0.945.511E (dropped on 01/02/2006 ?)
Finally replaced by: 1C0.945.511A (dropped on 01/08/2007 ?)


Replacement switches can be sourced from

• Euro Car Parts
• GSF (Need to double check)
• I believe that VW Dealers also sell them .

As the parts history testifies, a broken BLS is so badly made, that it's not worth repairing. Simply dispose of it in an environmentally respectful manner.


Useful Links:

1) VWVortex: Installing a new brake light switch (without breaking it!)
2) VWVortex: Removing interior parts II (dash trim, brake-light switch ...)
3) Jason Ettorre: Repairing the Brake Light Switch on your Mk4 ...

TR7

[elPaulio]

Nice write up mate!!

Explains a lot about why this fault appears to be popping up more often!!

Much kudos to you!!

Paul