Abs problems

Kev75 · 29th July 2020, 20:00

Hello there.

I have a 2002 rover 75 diesel conny.
When starting sometimes the abs light comes on for self then goes out as it should but when driving when I brake there is a grinding/scaping noise at the front sonds like the brake pads are down to the metal (there not about1/4 wonn) the brake pedal vibrates/shudders a bit when nearly stopped,

if the abs warning stays on in self test then driving the brakes feel good no noises when braking no pedal vibes,
I have checked/cleaned all 4 sensor plugs and the big connector on the abs unit
The cruise control is working so is the speedo.
Is there a way to check/ run the abs unit? Thanks in advance.

Kev

vitesse · 29th July 2020, 20:21

Sounds like it's one of the rear sensors actually, but instead of guessing get yourself a copy of the freeware Toaf (use the search) and it'll tell you which corner it is.

Regards

trikey · 29th July 2020, 20:27

Its normally a failed rear bearing when this happens, check the condition of the backplates around the stub axle, these can rot inwards and damage the seal on the bearing (Where the sensor picks up the signal from)

Kev75 · 29th July 2020, 20:46

Hi there

Would the abs unite make strange noises with a sensor gone

Kev

trikey · 29th July 2020, 20:49

Quote:

Originally Posted by Kev75

Hi there

Would the abs unite make strange noises with a sensor gone

Kev

Yes, the abs will activate at slow speeds (Just before you stop) And you will get feedback through the pedal.

Kev75 · 29th July 2020, 20:56

OK thank you I will have look at rear bearings and backplates.

Kev

trikey · 29th July 2020, 21:00

Quote:

Originally Posted by Kev75

OK thank you I will have look at rear bearings and backplates.

Kev

You wont be able to see the rust unless you remove the wheel bearing first.

Mike Noc · 30th July 2020, 06:56

Start with the offside bearing.

Kev75 · 30th July 2020, 12:34

Hello again.

Took the rear hubs off there was a bit rust and dirt on the hub and backplate cleaned it all up, the backplate does need replacing but nothing too bad. Took for test drive still the same

with the abs light off strange noises at the front when braking when the abs light on no noises plus getting brake warning light now. The bearings both looked and felt fine. I have never been in a car when the abs has been activated but would not expect the noise I can hear as I said it sounds like pads worn to the metal

Help please.

Kev

Mike Noc · 30th July 2020, 14:01

Courtesy of French Mike you can check all the ABS sensors and magnetic reluctors in the wheel bearings using a voltmeter.

The signal voltage changes from 1.7V to 0.7V as each magnetic segment passes the sensor, so jack each wheel in turn and slowly rotate it marking the switch points on the tyre wall with chalk. You should end up with 48 chalk marks. As you can see from the second photo my offside rear wheel sensor was missing quite a few segments, caused by rust damaging the magnetic reluctor. First photo shows what the sensor should be picking up.

If any gaps are in the same place each revolution then likely a damaged reluctor, and if in random places suspect the sensor or possibly a slightly too big air gap.

29th July 2020, 20:00	#1
Kev75 Avid contributor Rover 75 Saloon Join Date: Apr 2012 Location: Nantwich Posts: 151 Thanks: 260 Thanked 41 Times in 34 Posts	Abs problems Hello there. I have a 2002 rover 75 diesel conny. When starting sometimes the abs light comes on for self then goes out as it should but when driving when I brake there is a grinding/scaping noise at the front sonds like the brake pads are down to the metal (there not about1/4 wonn) the brake pedal vibrates/shudders a bit when nearly stopped, if the abs warning stays on in self test then driving the brakes feel good no noises when braking no pedal vibes, I have checked/cleaned all 4 sensor plugs and the big connector on the abs unit The cruise control is working so is the speedo. Is there a way to check/ run the abs unit? Thanks in advance. Kev

29th July 2020, 20:27	#3
trikey Premium Trader Rover 75 Join Date: Nov 2010 Location: Devon Posts: 33,774 Thanks: 8,837 Thanked 14,831 Times in 8,030 Posts	Its normally a failed rear bearing when this happens, check the condition of the backplates around the stub axle, these can rot inwards and damage the seal on the bearing (Where the sensor picks up the signal from) __________________ Lest we forget..

29th July 2020, 20:21	#2
vitesse I really should get out more....... Rover 75 Saloon Join Date: Jul 2011 Location: Gävle Posts: 2,537 Thanks: 395 Thanked 823 Times in 652 Posts	Sounds like it's one of the rear sensors actually, but instead of guessing get yourself a copy of the freeware Toaf (use the search) and it'll tell you which corner it is. Regards

29th July 2020, 20:46	#4
Kev75 Avid contributor Rover 75 Saloon Join Date: Apr 2012 Location: Nantwich Posts: 151 Thanks: 260 Thanked 41 Times in 34 Posts	Hi there Would the abs unite make strange noises with a sensor gone Kev

29th July 2020, 20:56	#6
Kev75 Avid contributor Rover 75 Saloon Join Date: Apr 2012 Location: Nantwich Posts: 151 Thanks: 260 Thanked 41 Times in 34 Posts	OK thank you I will have look at rear bearings and backplates. Kev

30th July 2020, 06:56	#8
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: 11,551 Thanks: 3,470 Thanked 3,119 Times in 2,247 Posts	Start with the offside bearing.

30th July 2020, 12:34	#9
Kev75 Avid contributor Rover 75 Saloon Join Date: Apr 2012 Location: Nantwich Posts: 151 Thanks: 260 Thanked 41 Times in 34 Posts	Hello again. Took the rear hubs off there was a bit rust and dirt on the hub and backplate cleaned it all up, the backplate does need replacing but nothing too bad. Took for test drive still the same with the abs light off strange noises at the front when braking when the abs light on no noises plus getting brake warning light now. The bearings both looked and felt fine. I have never been in a car when the abs has been activated but would not expect the noise I can hear as I said it sounds like pads worn to the metal Help please. Kev

30th July 2020, 14:01	#10
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: 11,551 Thanks: 3,470 Thanked 3,119 Times in 2,247 Posts	Courtesy of French Mike you can check all the ABS sensors and magnetic reluctors in the wheel bearings using a voltmeter. The signal voltage changes from 1.7V to 0.7V as each magnetic segment passes the sensor, so jack each wheel in turn and slowly rotate it marking the switch points on the tyre wall with chalk. You should end up with 48 chalk marks. As you can see from the second photo my offside rear wheel sensor was missing quite a few segments, caused by rust damaging the magnetic reluctor. First photo shows what the sensor should be picking up. If any gaps are in the same place each revolution then likely a damaged reluctor, and if in random places suspect the sensor or possibly a slightly too big air gap.