ABS Sensor: ABSolute pain!
Hi,
1) Scenario
Car was left parked up/undriven (during several days of very wet weather), and after driving it I noticed that the ABS and ASR (traction control) lights were lit on the dashboard. This didn't seem to affect normal driving and braking, but I did take note and drove cautiously nonetheless.
Managed to scan for fault codes later on, and from the ABS Controller (Address 03) retreived;
00283 - Front Left ABS Wheel Speed Sensor (G47)
012 - Electrical Fault in Circuit
This suggested a fault with either the wiring/connections to the Front Left ABS Sensor, or to the Sensor itself. I ordered a replacement Front Left sensor [1J0.927.803].
2) Attempted Fix
Today, I optimistically tried to determine the fault. Haynes details the steps in Chapter 9.20. Below is my interpretation of this procedure ;)
1) Remove wheel nut covers
2) Lightly loosen wheel bolts
3) Jack up front left of car and also position on axle stand
4) Chcck rear wheels
5) Remove wheel bolts
6) Remove wheel
7) Try and remove connector to ABS Sensor
8) Wow, isn't this sensible. The clip to remove the ABS sensor is obstructed by the shock absorber, so I can't easily remove the ABS connector.
Perform (7 to 8) until you loose patience and pull the connector to the ABS sensor out violently :(
9) Unscrew bolt that retains ABS sensor to hub (5mm hex head).
10) Remove ABS Sensor from car
11) Remove very tightly jammed/rusted ABS Sensor from car
12) Loosen ABS Sensor with copious amounts of WD40
13) Try and tap out or lever ABS Sensor
Perform (11 to 13) until you realise this isn't going to happen :aargh4:
The old ABS Sensor is corroded into place, and simply won't come out.
At this point, I tried to ensure that the ABS Sensor really did need to be removed, and plugged in the replacement sensor, then scanned for fault codes.
After clearing the pre-existing 00283.12 fault code, a rescan proved that the new ABS Sensor was actually working properly, and the old one did indeed need replacement.
The old ABS Sensor, had what looked like iron fillings /rust attached to it's magnetic sensor head (would this cause ABS sensor failiure, and can this just be cleaned up ?)
3) Questions and What Next ?
a) What caused the ABS Sensor to fail ? Was it the rain ?
b) What effect does the rust have on the ABS Sensor, would cleaning this up fix the sensor and how best to clean this ?
c) In as much detail as possible please, how should the ABS Sensor be removed ?
The ABS Sensor is like a corrupt politician: Once it's in for too long, it's a real b*****d to remove. :o
- It's plastic so how much pulling,pushing or abuse will it take before breaking ?
- I've tried pulling it that doesn't seem to work
- It appears to be stuck in the front hub housing. Should it be pushed out from the front. (the disk brake would need to be removed, but the ABS rotor would still be in the way) ?
d) How safe is the car to drive with a faulty ABS Sensor ? (I expect that neither ABS nor ASR traction control will work)
e) Will the car fail its MOT with ABS not working ?
Would really appreciate your experience in this, particularly regarding removing the old ABS Sensor.
It seems easy enough, but because it's made of plastic, and covered by the disc and the ABS rotor it's much more difficult to remove that I would have imagined.
Thanks,
TR7
Re: ABS Sensor: ABSolute pain!
Very disappointed with the lack of response on this post. :(
I managed to replace the ABS sensor myself, and (just for the record) will post my own answers to most of the above questions.
How safe is the car to drive with a faulty ABS Sensor ?
Quote:
Originally Posted by
tornadored7
d) How safe is the car to drive with a faulty ABS Sensor ? (I expect that neither ABS nor ASR traction control will work)
Unfortunately, I had first hand experience of urgently requiring ABS when its wasn't operational.
A driver decided to undertake me, then pull in front of me and brake sharply (:confused:), forcing me to hit the brakes very hard without the benefit of ABS. There was a huge cloud of smoke, the brakes locked and my car swerved slightly.
Very fortunately, I was able to control the car, so no one was hurt and I managed to avoid an accident.
However, I was furious, more so considering that my baby seated in the back could have been hurt. After composing and restraining myself, I decided to drive off in any direction that the halfwit driver wasn't heading.
Ironically I was trying to leave a little extra safety braking distance because of the ABS, not invite halfwits to test my braking reaction times.
Obviously, without ABS the car is much less safer. Without ABS, the brakes don't seem as sharp, the brakes will lock (if pushed hard) and given sufficiently slippery road conditions, traction control won't intervene to assist.
Personally, I'd drive as carefully as possible (being aware of halfwits), or try and avoid driving until the ABS sensor is fixed.
Re: ABS Sensor: ABSolute pain!
Hi. My A3 19996 is due for its mot soon nd guess what.....the abs light stays on. I'm getting a pulsing action on the brake pedal when im slowing down. A mechanic has checked the pads and disks and cant see any problem with them. Any suggestions to what the problem may be/how to fix it/how much it may cost to get fixed?
Iv read that it may just be a "simple" case of dirty sensors? Could this be the answer?
Re: ABS Sensor: ABSolute pain!
so deff not a siezed brake caliper then ??;):confused:;)
Re: ABS Sensor: ABSolute pain!
Quote:
Originally Posted by
spritefzr
Hi. My A3 19996 is due for its mot soon nd guess what.....the abs light stays on. I'm getting a pulsing action on the brake pedal when im slowing down. A mechanic has checked the pads and disks and cant see any problem with them. Any suggestions to what the problem may be/how to fix it/how much it may cost to get fixed?
Iv read that it may just be a "simple" case of dirty sensors? Could this be the answer?
Hi spritefzr,
I think the fact that the ABS light stays on is actually good news, since it suggests that something may have registered/flagged a fault, and the ECU is aware of it.
Hopefully, this should make the diagnosis procedure easier, and you won't necessarily have to guess the issue.
I'd suggest getting your fault code scanned (i.e. use VAG-COM), which should be helpful in isolating the issue. After retrieving any fault codes (and saving somewhere safe), clear any ABS/ASR/ESP related fault codes, drive normally and rescan for any fault codes.
I have heard of both damaged ABS rotors and misaligned/damaged ABS speed sensors producing the symptoms you have described but I'd prefer to;
Let the fault codes, help determine the underlying issue.
BTW, does only your ABS light come on, or does your Traction control ASR/ESP light also illuminate ?
TR7
P.S. Is your highly futuristic 19996 A3 powered by Flux Capacitors ? :Blush:
Re: ABS Sensor: ABSolute pain!
Cheers guys. looks like I have to get it checked out. Hopefully nothing too expensive to fix. In reply to your question, only the abs light comes on. I that good?
Tornadored7, the problem is I only really need the abs when I travel back to 2008. In the year 19996 we DONT NEED ROADS!! Additinally I dont feel safe drivening at the reqiured 88mph needed for the flux capacitor to kick in with the abs light on.
Only the ABS light comes on ...
Quote:
Originally Posted by
spritefzr
In reply to your question, only the abs light comes on. I that good?
Hi Sprite,
If both the ABS and TCS light were activated, then it's more likely to be an ABS/Speed sensor or wiring issue.
Otherwise, it does begin to look more akin to a problem in the ABS or braking systems. Any results from the fault code scan ?
BTW, I've found the following web site useful for Flux Capacitor related issues; http://www.deloreans.co.uk/ :Blush2:
TR7