ABS sensor problems, ZT cdti, any help please.

GHS · 21st February 2014, 06:35

My ABS sensor warning light came on a while since and the speedo stopped working as they both work from the same thing (or so i am told).
Car has been on a diagnostics machine which showed the problem was the offside front wheel. Had new sensor fitted yesterday but warning light still on and no speedo, mechanic tried to sort the problem but to no avail, stumped. Has anyone any advice or a solution to this please.

Mike Noc · 21st February 2014, 07:14

If you get an old ABS plug and socket from a scrappie and connect a long cable between them you can plug any sensor into the OSF.

That will show which side of the plug and socket the fault is on. The sensors pick up a magnetic reluctor which is built into the bearings.

Using French Mike's method you can also test each individual segment on the reluctor by connecting a voltmeter - if you connect the extended plug and socket with chocblock you can pin the signal at the block.

You are looking for the signal switching between 0.7 volts and 1.7 volts as the segments pass the sensor.

If you get no speedometer reading from any sensor and all the wiring from the OSF plug back checks out then it could be an ABS pump fault, and a T4 diagnostic check should be able to confirm this.

The ABS pump multiplug pins can suffer corrosion - it sits under the battery compartment.

GHS · 21st February 2014, 07:37

Crikey Mike, will have to let the mechanic read this. Thank you so much for this reply.

Mike Noc · 21st February 2014, 08:03

You're welcome. Forgot to mention the rear ABS plugs are located just behind the rear seat back.

Let us know how he gets on.

350zwelgje · 21st February 2014, 08:08

If speedo still not working, seems to me the same problem is still there at the same wheel. Could be that the reluctor ring is not ok and the sensor was/now is. To replace the reluctor ring it needs a new front wheel bearing as it is incorporated.

Rob

GHS · 21st February 2014, 11:26

Thanks Rob, will get him to read these and see if we can come up with a solution

21st February 2014, 06:35	#1
GHS Newbie MG ZT Join Date: Jun 2012 Location: Driffield Posts: 22 Thanks: 0 Thanked 0 Times in 0 Posts	ABS sensor problems, ZT cdti, any help please. My ABS sensor warning light came on a while since and the speedo stopped working as they both work from the same thing (or so i am told). Car has been on a diagnostics machine which showed the problem was the offside front wheel. Had new sensor fitted yesterday but warning light still on and no speedo, mechanic tried to sort the problem but to no avail, stumped. Has anyone any advice or a solution to this please.

21st February 2014, 07:14	#2
Mike Noc This is my second home Rover 75 CDT Manual Connoisseur SE, Rover 75 CDT Automatic Connoisseur SE & a Freelander Td4. Join Date: Jul 2009 Location: Hampshire Posts: 11,585 Thanks: 3,470 Thanked 3,119 Times in 2,247 Posts	If you get an old ABS plug and socket from a scrappie and connect a long cable between them you can plug any sensor into the OSF. That will show which side of the plug and socket the fault is on. The sensors pick up a magnetic reluctor which is built into the bearings. Using French Mike's method you can also test each individual segment on the reluctor by connecting a voltmeter - if you connect the extended plug and socket with chocblock you can pin the signal at the block. You are looking for the signal switching between 0.7 volts and 1.7 volts as the segments pass the sensor. If you get no speedometer reading from any sensor and all the wiring from the OSF plug back checks out then it could be an ABS pump fault, and a T4 diagnostic check should be able to confirm this. The ABS pump multiplug pins can suffer corrosion - it sits under the battery compartment. Last edited by Mike Noc; 21st February 2014 at 07:23..

21st February 2014, 08:08	#5
350zwelgje Avid contributor 75 KV6 2.5 3x Rover 75 CDT Join Date: Jan 2011 Location: Belgium Posts: 249 Thanks: 6 Thanked 34 Times in 33 Posts	If speedo still not working, seems to me the same problem is still there at the same wheel. Could be that the reluctor ring is not ok and the sensor was/now is. To replace the reluctor ring it needs a new front wheel bearing as it is incorporated. Rob __________________ 75 KV6 2.5 Sterling automatic, 3x 75 CDT (2 manual + automatic), MG ZT 190+, 620i, SD1 2300S, P6 2000SC & TVR 350i

21st February 2014, 07:37	#3
GHS Newbie MG ZT Join Date: Jun 2012 Location: Driffield Posts: 22 Thanks: 0 Thanked 0 Times in 0 Posts	Crikey Mike, will have to let the mechanic read this. Thank you so much for this reply.

21st February 2014, 08:03	#4
Mike Noc This is my second home Rover 75 CDT Manual Connoisseur SE, Rover 75 CDT Automatic Connoisseur SE & a Freelander Td4. Join Date: Jul 2009 Location: Hampshire Posts: 11,585 Thanks: 3,470 Thanked 3,119 Times in 2,247 Posts	You're welcome. Forgot to mention the rear ABS plugs are located just behind the rear seat back. Let us know how he gets on.

21st February 2014, 11:26	#6
GHS Newbie MG ZT Join Date: Jun 2012 Location: Driffield Posts: 22 Thanks: 0 Thanked 0 Times in 0 Posts	Thanks Rob, will get him to read these and see if we can come up with a solution