Hand brake light - erratic flashing

[jonkoxe11]

Hi all

I am a recent newby to Z4 e89 ownership and currently working through a number of issues.
I have a 2010 35is which is suffering from an erratic handbrake light.
Sometimes it works, sometimes it doesn't, other times it flashes erratically.
It does not seem like the same symptoms that other posts say can be fixed with a software update. I have checked the fluid level and removed the wiring connectors from both actuators, checked and cleaned the contacts etc.
How is the light activated? Is there a micro switch somewhere?

Thank you for your help
Jon

 

[matsmith749]

When you say handbrake light, are you refferring to the red LED on the eBrake switch in the centre console panel just in fron tof the armrest?

The wires for this can be accessed by removing the panel (easy job).

Ignoring the light - is the eBrake functioning ok? You should hear it activating / deactivating etc.

 

[jonkoxe11]

Hi
It is the light within the cluster.
The switch light functions correctly as does the handbrake mechanism. There are no issues other than the erratic cluster light.
It is as if there is a poor connection somewhere.

Jon

 

[matsmith749]

Ah ok - what happened when you scanned it for codes?

(you know that's the first step, right?)

An 'blinky' cluster light could be any wire or connection in the 15 linear miles of cabling thoughout the car.... good luck tracking that down.

 

[jonkoxe11]

No codes are being thrown but I only have the Autofix 7910 scanner. Does a decent job but falls short of finding a dodgy connection :roll:

 

[Pondrew]

Sounds like it may be a brake pad sensor playing silly buggers. One on one front disc (can't remember which one) and one on the diagonally opposite rear. Check they are both intact and wiring is all connected securely.

If it is a sensor, my advice would be to cut the bloody things off and tape the ends of the wires. More trouble than they are worth IMO.

 

[jonkoxe11]

Hi Pondrew
That is a good point. After I viewed the car the garage did discs and pads all around which I can see also included new ware sensors too.
I did not notice any flickering when i viewed the car and I was with it for a couple of hours. It started a few weeks after it was delivered.

 

[flybobbie]

Mine does the same since i had some abs problems and i replaced the abs unit.
But i am convinced it's a loose wire somewhere.
I can press various parts of the centre dash and i get some change of flicker, just given up for the moment trying to solve.
Gone through mot ok.

 

[jonkoxe11]

It is frustrating though.
The car was parked up for just over a week on the drive with handbrake on.
Went to use it yesterday and instantly noticed the light was on. Drove the car a few miles and now nothing again.
Is there a microswitch that triggers the light. It must be within the electronic parking brake actuator or somewhere so the system knows if the pads are actually touching the disc. Maybe a force activated system that detects a resistance.
Anybody know how this things works?

 

[Pondrew]

The only thing I know is the handbrake motors are controlled by current switches. That's how they can adjust with the wearing of the pads.
Judging by how complicated electrical systems on cars are, I doubt there is anything as simple as a microswitch to switch the light on and off.

 

[B21]

If it’s an EMF failure you get both a red brake warning AND a yellow brake warning in the central display..

I assume you don’t have idrive?

 

[jonkoxe11]

No yellow or red.
I do have iDrive. Is this helpful for finding the fault?

 

[flybobbie]

Check to see if you still have tyre pressure monitoring.
iDrive flags up on my car failure.
Can't be reset.
Nothing on obd readout though.

I replaced the two front speed sensors.
Could be system doesn't like them (after market?) but cars stops and brakes ok. No traction warnings.

 

[B21]

No yellow or red.
I do have iDrive. Is this helpful for finding the fault?

Have you checked on idrive the service information for front and rear brakes ?

 

[jonkoxe11]

No yellow or red.
I do have iDrive. Is this helpful for finding the fault?

Have you checked on idrive the service information for front and rear brakes ?

I have checked the drive and used a code scanner and there is nothing showing as wrong. No codes thrown up and idrive reports all ok.

 

[Pondrew]

I have checked the drive and used a code scanner and there is nothing showing as wrong. No codes thrown up and idrive reports all ok.

Check those pad sensors! Easy to 'not see the wood for the trees'. Don't think wear sensors are monitored by the 'puter', so wouldn't log a fault.

 

[jonkoxe11]

I have checked the drive and used a code scanner and there is nothing showing as wrong. No codes thrown up and idrive reports all ok.

Check those pad sensors! Easy to 'not see the wood for the trees'. Don't think wear sensors are monitored by the 'puter', so wouldn't log a fault.

I will take another look at all wiring including the wear sensors.
Probably time to get familiar with the wiring diagram.