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Vauxhall Astra - ABS fault - all 4 wheel speed sensors show a fault at same instant - Fixed #

Posted by Martin Kelly on July 23, 2016, 2:11 pm

Year of Manufacture *: 2008

Hi, this fault occurrs intermittently, and for only about 1 second or less, at speeds between 25 and 70mph.
Some times when brake pedal is depressed the ABS operates as it thinks there is a wheel speed problem at that instant - which there is!

No DTC's logged.

The screenshot below shows that when it happens at around 30mph the following speeds are detected at the green cursor line;
Front Left 78mph - increase
Front right 105mph - increase
Rear left 21mph - decrease
Rear right 0mph - decrease

When the fault happens at whatever vehicle speed the same false readings above are shown.

I have been able to swap control unit for an identical unit and the fault still occurrs.

Could a single faulty wheel speed sensor have this effect on the other 3 wheel speed sensors?

Any help here would be most appreciated.

Thanks, Martin.

Re: Vauxhall Astra - ABS fault - all 4 wheel speed sensors show a fault at same instant.

Posted by andy pethig <iframe src='https://members4.boardhost.com/ukautotalk/info/user=ukat3731' width='330' height='300' border=0 style='border:none;'> on July 23, 2016, 4:07 pm, in reply to "Vauxhall Astra - ABS fault - all 4 wheel speed sensors show a fault at same instant."

what is the repair history of the abs system. or the car for that matter , we see a lot of funky stuff from poorly crash repaired cars,

4 cheep sensors could be the problem, buy a front one and try it could be one method, if that does not work .... move on .

the fact that the front and rear faults are mirrored is a clue, and will depend on what type of sensor is fitted,

If you have a scope have a look at what you get from the front right at 30 mph you should be able to do this on a jack , as this sensor looks like the worst offender .

you could also try unclipping the 2 front sensors from behind the CV joint and drive it and see if you get a increase in road speed on the scan tool when the fault happens .

if you do it would suggest a wiring fault and not a sensor/ reluctor fault

Strange fault ,

Re: Vauxhall Astra - ABS fault - all 4 wheel speed sensors show a fault at same instant.

Posted by tony bickers <iframe src='https://members4.boardhost.com/ukautotalk/info/user=UKAT5143' width='330' height='300' border=0 style='border:none;'> on July 23, 2016, 5:31 pm, in reply to "Re: Vauxhall Astra - ABS fault - all 4 wheel speed sensors show a fault at same instant."
Anthony Bickers

As Andy has hinted at,bet you have an ECP or GSF sensor fitted on one corner !

Re: Vauxhall Astra - ABS fault - all 4 wheel speed sensors show a fault at same instant.

Posted by Tim Watts <iframe src='https://members4.boardhost.com/ukautotalk/info/user=ukat3942' width='330' height='300' border=0 style='border:none;'> on July 24, 2016, 9:22 am, in reply to "Vauxhall Astra - ABS fault - all 4 wheel speed sensors show a fault at same instant."
Tim Watts

Seeing live data I would be looking for o/s/r air gap fault. Possibly wheel bearing play or rust under sensor seat. Maybe even grabbing or binding brake.

The ecu will cope with fairly large speed differances without error but any drop out off signal sounds alarm bells which will reset once all signals return.

Re: Vauxhall Astra - ABS fault - all 4 wheel speed sensors show a fault at same instant.

Posted by Martin Kelly <iframe src='https://members4.boardhost.com/ukautotalk/info/user=UKAT2863' width='330' height='300' border=0 style='border:none;'> on July 25, 2016, 8:34 pm, in reply to "Re: Vauxhall Astra - ABS fault - all 4 wheel speed sensors show a fault at same instant."
Martin Kelly

Hi, thanks for your replies.
We have looked after this car for about 5 years, no signs of any accident damage, no wheel speed sensors fitted in that time ( built into hub bearings), all bearings ok.
This afternoon I disconnected both rear speed sensors and went on road test and the front ones spiked as before.
Tomorrow I'll disconnect the fronts.

Thanks, Martin.

Re: Vauxhall Astra - ABS fault - all 4 wheel speed sensors show a fault at same instant.

Posted by Tony Ludford <iframe src='https://members4.boardhost.com/ukautotalk/info/user=UKAT5539' width='330' height='300' border=0 style='border:none;'> on July 26, 2016, 6:53 am, in reply to "Re: Vauxhall Astra - ABS fault - all 4 wheel speed sensors show a fault at same instant."
Tony Ludford

Is it a petrol? Just an out there thought: Coil pack spiking?

Re: Vauxhall Astra - ABS fault - all 4 wheel speed sensors show a fault at same instant.

Posted by andy pethig <iframe src='https://members4.boardhost.com/ukautotalk/info/user=ukat3731' width='330' height='300' border=0 style='border:none;'> on July 26, 2016, 6:09 pm, in reply to "Re: Vauxhall Astra - ABS fault - all 4 wheel speed sensors show a fault at same instant."
Andrew Pethig

continuing in the way out there theme ,
try disconnecting the live batt cable from the alternator ,
if the wheel speed sensors are a VRS type ( which i don't thing they are but..) and the alternator is bleeding some AC voltage in to the system this will mess with any sensors that are producing there own voltage as this will also be AC.

Re: Vauxhall Astra - ABS fault - all 4 wheel speed sensors show a fault at same instant.

Posted by Martin Kelly <iframe src='https://members4.boardhost.com/ukautotalk/info/user=UKAT2863' width='330' height='300' border=0 style='border:none;'> on July 27, 2016, 7:18 am, in reply to "Re: Vauxhall Astra - ABS fault - all 4 wheel speed sensors show a fault at same instant."
Martin Kelly

Hi,
Tony, it is petrol Z14XEP, engine runs very smooth, no codes.
Andy,this may answer you point; yesterday I disconnected both front WSS and monitored the rears on a 25 mile drive home and they behaved normally with no abnormalities.
I'll now reconnect the fronts one at a time and repeat the road test.

Many thanks, Martin.

Fixed #

Posted by Martin Kelly on July 30, 2016, 6:49 pm, in reply to "Re: Vauxhall Astra - ABS fault - all 4 wheel speed sensors show a fault at same instant."
Edited by board administrator August 1, 2016, 8:07 am

Hi, with front right and both rears connected fault only occurred once in 25 mile drive, reconnected front left and fault happened consistently.
I then scoped both fronts and there was alot of dropout on FL, some on FR but nowhere near as bad as FL.
When I removed the FL bearing assembly the sensor mounted ring was so badly corroded it separated from the bearing.
Have advised customer that FR will probably need replacing soon as well.

So, one bad ABS sensor can affect the other 3 then.

Thanks for your help, Martin.

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