Brake Pad dash warning light on after new pads

hitechtherealone

Registered User
Hi this is a bit of a head scratcher. I had this car in for a service. Done the service and noticed that the brake pad wear sensor had lit up the dash light. I asked the customer who said its been like that since last guy changed the pads. I checked the pads. plenty left on them. Checked the sensors. front and back.They both trace out as short and not open which is what they should anyway.So whats the script. Dont see anything in VCDS for any kind of reset or anything. Its quite a head scratcher. Ive even checked for continuity from connector all way back and everything checks out. Nothing shows up on a diagnostic scan.What an earth????? Anybody shedsome light on this please. If only for my own sanity to understand this very bizarre fault.
 

DJAlix

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Hi this is a bit of a head scratcher. I had this car in for a service. Done the service and noticed that the brake pad wear sensor had lit up the dash light. I asked the customer who said its been like that since last guy changed the pads. I checked the pads. plenty left on them. Checked the sensors. front and back.They both trace out as short and not open which is what they should anyway.So whats the script. Dont see anything in VCDS for any kind of reset or anything. Its quite a head scratcher. Ive even checked for continuity from connector all way back and everything checks out. Nothing shows up on a diagnostic scan.What an earth????? Anybody shedsome light on this please. If only for my own sanity to understand this very bizarre fault.
Common issue on a8 vehicles which is how I know about it :(The wear sensor wiring loom has corroded and will need tracing back and replacing. Could be one corner or more.
 

hitechtherealone

Registered User
A broken wire anywhere on the loom would indicate an open circuit. There are no open circuits with the pad sensors. They check out closed circuit, both ends.

Common issue on a8 vehicles which is how I know about it :(The wear sensor wiring loom has corroded and will need tracing back and replacing. Could be one corner or more.
 

elan2s

Registered User
Not entirely sure no. This thing is a UK S-line thing. if im in wrong place my apologies. where should I go ?

If it is on a 68 or 19 plate and has the twin touch screen set up on the dash for navigation and climate then you are in the right place. If it has the pop up nav screen (probably on a 61 to 18 plate) the it is a c7 type. If it has the nav screen fixed on the dash next to the main dials (probably on a 06 to 11 plate) then it is a c6 type


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elan2s

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C7 forum.


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B5NUT

Well-Known Member
VCDS Map User
Nothing to be sorry about, just helpful to know the correct car as it makes it easier to diagnose the fault. I take it you don't have any diagnostic scans of the car. There are only two sensor cables one front, one rear. It's also unlikely the cables have corroded in just one 4 years When he changed the pads were they ones with the sensors or after market without.
 

RAF_S7

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DJAlix

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A broken wire anywhere on the loom would indicate an open circuit. There are no open circuits with the pad sensors. They check out closed circuit, both ends.
Yes indeed however I am talking about corrosion which not only “breaks” wires but can fuse wires together.
 

V6_Man

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hitechtherealone

Registered User
I have come across some mercedes where corrosion orheat has boned wires together and therefore the actual circuit is still short as it should be but the resistance is slightly diffirent for the ECU to detect the diffirence. Would you say this is the diffirence. If one of the sensors had actually had its wired short together then a dead short is enough to throw up the brake pad wear fault/warning ?

The pads are after market PAGID pads that is all ive investigated so far. Ive got this car coming back on Tuesday so have to get to the bottom of it.

A full diagnostic VCDS scan comes up with nothing to do with brake pad wear sensor which adds to the head scratching.

Yes indeed however I am talking about corrosion which not only “breaks” wires but can fuse wires together.
 

DJAlix

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I have come across some mercedes where corrosion orheat has boned wires together and therefore the actual circuit is still short as it should be but the resistance is slightly diffirent for the ECU to detect the diffirence. Would you say this is the diffirence. If one of the sensors had actually had its wired short together then a dead short is enough to throw up the brake pad wear fault/warning ?

The pads are after market PAGID pads that is all ive investigated so far. Ive got this car coming back on Tuesday so have to get to the bottom of it.

A full diagnostic VCDS scan comes up with nothing to do with brake pad wear sensor which adds to the head scratching.
Not 100% sure on the ins and outs of how it works, or doesn’t in this case, and was surprised myself but between DHAutomotive / MRC Scotland and myself we have seen a number of vehicles with this very issue since diagnosing it for the first time.
 

hitechtherealone

Registered User
Its a bit bizarre, what has been your prognosis and fix on it? Actual loom replacement of faulty sides? Finding out exactly where this fault is occuring would be quite important for Audi I would think as it seems to becoming a common expensive fault for customers who have cars just out of warranty.

Not 100% sure on the ins and outs of how it works, or doesn’t in this case, and was surprised myself but between DHAutomotive / MRC Scotland and myself we have seen a number of vehicles with this very issue since diagnosing it for the first time.
 

hitechtherealone

Registered User
Not much input in here. I returned the car to the customer with my honest admittal that I cant find the fault, Nothing shows up on a full VCDS scan and everything has been ruled out as far as pads and sensors go. New pads/sensors been changed out twice and also old ones put back on out of curiosity. Continuity readings for wiring to each wheel including sensors and ABS. Each set of wiring showing a complete circuit. No open circuits. The only test that was not carried out was to behind the dashboard into the cluster. The likelyhood of a fault in the cluster is so slim its not worth the time and labour. This was also advised to the customer. Software update or reflash or whatever the dealer can do is my suggestion. The customer has bad a bad experience with Highland Audi in Inverness previously though so unfortunately they lost the customers trust there completely. Most likely they will shift the car on in a tradein. Wouldnt waste any more time/effort/stress/money over it.
 
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