Mysterious Brake Pad Warning

M-A8 · #1 4th January 2017, 03:34 PM

Hello
I didn't want to hijack 1781cc's thread further so here is a separate thread about my mysterious brake pad warning I mentioned the other day.

Don't know if this is just coincident or it has anything to do with it, but in September when car went for a full and comprehensive service inc. gearbox service, all the fluids, wheel bearings etc, I've had also rear pads replaced as the rear suspension was completely stripped down and rear pads were low anyway.
Front pads hasn't been touched, but the brake fluid has been changed.

I can't remember exactly if it was week or two or three since all the work, hence me thinking it's just the coincident as it wasn't straight after, when I got the first brake pad warning light on the dash.

It has been like that since, originally I've scanned the [03] ABS ECU for faults, but there was non. Then in 1781cc's thread it has been suggested to also look in [53] Parking Brake ECU. It took a good week or so for the fault to come back (I didn't drive much recently anyway), but it finally did.

For a second today I thought this could be related to ESP because the fault came on after getting the rear end a bit happy which happened quiet often in past few weeks due to wet conditions, but I've ruled that out on basis that fault was coming on even on motorways driving steady and in dry conditions in October and November.

I did scan both ECUs while fault was still flashing on the dash and there was nothing, absolutely no faults whatsoever.
See attached photos.

Any clue what this might be??

I haven't get to the stage of replacing the EPB ECU yet as it was suggested few days ago.

Thanks guys

mattylondon · #2 4th January 2017, 03:45 PM

That looks like front pad warning either G34 Front Left wear sender or G35 Front Right, which is controlled by [17] Instruments. Check wiring to front pads and [17] for stored faults

M-A8 · #3 4th January 2017, 04:19 PM

Will do and thanks Matty.
Been in a little rush so had no time to do a full scan.

On what basis are you suggesting front pads if there is no faults in either of the ECUs??
Is there a different warning for the rear pads ??

M-A8 · #4 4th January 2017, 04:38 PM

Just did a quick selective scan as I'm still on the go.
Nothing in Cluster, Level Control, gearbox or CAN gateway, I mean no faults whatsoever ?!?!

paulrstaylor · #5 4th January 2017, 05:04 PM

I don't thing there is a fault logged for front pads on the D3, just a simple light on the dash - Check the front pads and the wiring would be my advice

M-A8 · #6 4th January 2017, 05:29 PM

That was the first thing I did when it happened for the first time...and I'm still checking pads every time i get the fault even if I know that there is plenty of meat left on the fronts.
Last time I just did a quick inspection with endoscope camera to check the inner pads due to access in case inner pad does wear quicker due to pistons being seized or whatever, but thats not the case.

I will take the wheels off soon to inspect wiring.

No log of the fault?? You 100% sure?? If there is warning light then why wouldn't be logged in?

I have also put a brand new (new revised type) brake light switch since it started happening. No cure of course.

Also I have disabled TPMS in CAN, Cluster or somewhere else I think before this fault, only because I am waiting for next tyre change, wheels refurb and all new sensors at the same time before summer. Don't know if that is relevant, but worth mentioning just in case.

Pug · #7 4th January 2017, 05:41 PM

'Conquistador' experienced a similar anomaly with his D3 S8, all it was just one of the wear wires (or sensor thing) that had come adrift, making it seem like the pads were worn. Audi couldn't even diagnose it, but we got it up on the ramp at my place of work, and it wasn't very hard to spot.

M-A8 · #8 4th January 2017, 05:45 PM

Quote:

Originally Posted by Pug

'Conquistador' experienced a similar anomaly with his D3 S8, all it was just one of the wear wires (or sensor thing) that had come adrift, making it seem like the pads were worn. Audi couldn't even diagnose it, but we got it up on the ramp at my place of work, and it wasn't very hard to spot.

Nice, thanks mate

Will defo get the wheels off soon to inspect it. Is it better to look from underneath or above??
Have you guys got any pictures??
Did you solder the wire back or ...??
I may actually call Ollie tomorrow or over the weekend.

paulrstaylor · #9 4th January 2017, 06:04 PM

Quote:

Originally Posted by M-A8

No log of the fault?? You 100% sure?? If there is warning light then why wouldn't be logged in?

Almost certain, check the wiring diagram to be sure but I think that it is a very simple circuit that loops round the left and right brake par wear sensors and to the cluster - not everything is logged by and ECU

One of the plugs had been damaged/cut on my old D3, ultimately it also affected the ABS sensor. I bought a partial loom from A8 Parts and spliced it in - on lesser models it is a plug in loom but sadly not on the A8

Could be the "sensor", plug or a wiring fault - but that is where my money is! If you want to cheat and you know your pads are okay, you can just short the pin to ground behind the cluster thus removing the function, again check the wiring diagram for details.

Pug · #10 4th January 2017, 07:30 PM

Quote:

Originally Posted by M-A8

Nice, thanks mate

Will defo get the wheels off soon to inspect it. Is it better to look from underneath or above??
Have you guys got any pictures??
Did you solder the wire back or ...??
I may actually call Ollie tomorrow or over the weekend.

The work was done by one of the technicians at my 'garage', and he simply said "the wear sensor had come adrift so I refitted it".

The technician was in the process of changing the pads anyway, so the car was already raised and wheels were off.