UROBARG

For the second time when I changed the pads the brake pad wear light would not go out out. The first time happened on my A6 earlier in the year. I spent a little time trying to figure out why, but since the car had 180k on it and I was selling it for a pittance, motivation was not high. I've replaced the pads many times on the A6 and '93 S4 and never had a problem before.

But this weekend I wanted to change the pads and rotors on my 2000 A8 and the same thing happened-
new pads but warning light still on.

Looking at the old pad plugs, there were signs
of corrosion. An OHM meter check across the new pads looked good. What I really needed to measure was upstream of the plug to the next connection (so that I was measuring with the new pads plugged in). There was a good posting back in '03 in this forum complete with the wiring diagram that talked about this. That was for a '99 A8. So the first task was to locate the right wiring diagram in the Bentley. This is a non-trivial exercise (their searching capability seemed a bit limited or maybe I just couldn't figure how to only search the 2000 info). Anyway, finally located it at 55-11.

So, again, I'm looking for the next connection upstream of the connection where the brake pad wear indicator plugs into the connector on the front strut. The description in the wiring diagram says T4ad and T4ae are the two connectors, one "in engine compartment, left" and the other on the right side. What they really mean is "if you want to locate this connector, trace the wires until you find it". Fortunately for these two, they were easily found behind the fender liner.

I unlocked two of the twist screws that hold on the under-car panel and removed the two 10mm nuts that were holding the panel where the wire disappears behind it.

Once I could bend the panel I could see the connector. I pulled the connector from it's mount and then using a small blade screw driver gently bent the tab on the connector until I heard an unpleasant snap, like I'd broken it. But that was the sound of the tab slipping free from it's matching surface on the other side of the connector and the connector easily slid apart.

So then it was easy to check continuity with my OHM meter. First I did the left side. Looked OK. Then did the same on the right side- also looked OK. Checked the dash and still the light was on. Went back to the right side.... there actually was some resistance. I took some fresh copper wire segments (maybe 16 gauge) and stuffed two or three (to get a good connection) across the two terminals on the plug near the wheel. I checked the warning light again, and now it was out.

At this point I'm guessing that some continuity isn't enough. My A8 wants no resistance. Maybe the combined corrosion of two plugs over 7 years and 80k miles was enough to fool the system into thinking it really was broken. Odd that this manifested itself after unplugging the old pads. There is no doubt the light should have been on- the wire from one of the old pads was just hanging down having been completely severed.

Anyway, I rolled up some fine grit sand paper and did my best to polish the inside of the plug and now the warning light doesn't come on.

So, in hindsight... if you see corrosion, assume that is the problem. Trying to locate the upstream connector didn't really help much. Then again, on my A6 I cleaned the contacts and gooped them with a conductive grease and still no luck in getting the light to go out.

Pads are an outrageous $200, but rotors at $100 seemed not unreasonable for Audi. The dealer gave me a 10% discount. Blau was about $80 cheaper, but shipping charges were over $40 so this time I went with the convenience of getting the parts for this weekend. I've got the Ate brakes (312mm rotors). Everything is more expensive if you have either of the other brake options.

Always Overcharged

occurs throwing the light and fault
See Audipages repair of wire.
Easy and cheap