ABS Problems at Low Speed - Page 7

Jakg · 26th April 2014, 18:37

Had another look today.

Removed the hub (the hub nut wasn't on very tight...) and it looked quite dirty so cleaned it (and the sensor) up, but didn't make any difference.

Replaced the hub (genuine MG Rover one off eBay for £80) and tested again and it worked fine. Replacing was much easier than I thought (although I had help!).

Didn't need a new sensor after all so will return.

Jakg · 13th August 2015, 12:42

Getting a similar problem again, where I can push the brake pedal about half way and then it gets "stuck" and won't go any further, as per ABS activation.

I can reproduce this by applying constant brake pressure, slowing, then turning the car about 90°. I then can't brake much harder. It sounds like an odd way of driving, but there's a corner nearby that requires it which made me find it out!

It also happens at low speeds very occasionally when turning and braking.

I've pulled the ABS fuse and it doesn't seem to be happening any more.

I don't think the problem is severe enough to be detected with the traditional "spin the wheels and count the pulses" approach?

The front & rear passenger side hubs are both new.

FrenchMike · 13th August 2015, 13:09

Quote:

Originally Posted by Jakg

Getting a similar problem again, where I can push the brake pedal about half way and then it gets "stuck" and won't go any further, as per ABS activation.

I can reproduce this by applying constant brake pressure, slowing, then turning the car about 90°. I then can't brake much harder. It sounds like an odd way of driving, but there's a corner nearby that requires it which made me find it out!

It also happens at low speeds very occasionally when turning and braking.

I've pulled the ABS fuse and it doesn't seem to be happening any more.

I don't think the problem is severe enough to be detected with the traditional "spin the wheels and count the pulses" approach?

The front & rear passenger side hubs are both new.

Yes Jack,the quickest way is checking each sensor in situ first .
(test static and dynamic)...

Good luck

Mike

HarryM1BYT · 13th August 2015, 13:37

As per FrenchMikes suggestion, if it shows up on the road at low speed, it will definitely show up with the count and mark the pulse method, slowly rotating the wheel.

The slower the wheel turns, the more susceptible it is to borderline pulses being missed by the ABS controller. The ultimate test for which, is rotating the wheel by hand and counting or marking on the tyre where the pulse occur.

Mike Noc · 13th August 2015, 15:33

Quote:

Originally Posted by Jakg

I don't think the problem is severe enough to be detected with the traditional "spin the wheels and count the pulses" approach?

As mentioned, the test will pick the fault up but, and I've had this before on my motorcycle, as the weight of the car will be off the wheel when you carry out the check, make sure the cable isn't damaged, or it may work perfectly whilst jacked up and then fault again once on the road.

Jakg · 27th September 2015, 19:01

Quote:

Originally Posted by Jakg

Getting a similar problem again, where I can push the brake pedal about half way and then it gets "stuck" and won't go any further, as per ABS activation.

I can reproduce this by applying constant brake pressure, slowing, then turning the car about 90°. I then can't brake much harder. It sounds like an odd way of driving, but there's a corner nearby that requires it which made me find it out!

It also happens at low speeds very occasionally when turning and braking.

I've pulled the ABS fuse and it doesn't seem to be happening any more.

I don't think the problem is severe enough to be detected with the traditional "spin the wheels and count the pulses" approach?

The front & rear passenger side hubs are both new.

More testing finds a segment missing on the passenger front. It had a new bearing within the last year so I've ordered a sensor instead. Heres hoping...

Mike Noc · 27th September 2015, 20:13

Is it missing at the same place every revolution?

If so then it will be the bearing not the sensor.

Jakg · 27th September 2015, 20:39

Quote:

Originally Posted by Mike Noc

Is it missing at the same place every revolution?

If so then it will be the bearing not the sensor.

I think it was intermittent, but I'm not 100%.

I'd be amazed if it was the bearing because it's new, and the sensor is original. I've bought one anyway now!

Jakg · 18th October 2015, 17:07

Replaced the passenger side sensor with one from DMGRS, which hasn't solved the problem, but it has solved the missing segment on the passenger side front.

I've now tested all of the wheels and all segments are present and accounted for. I've tested again with the ABS fuse out and the issue goes away so it's definitely an ABS issue.

The only oddity is that I don't seem to be getting the same output on the drivers side front - it alternates between 0.5-1* on all the other wheels, but between 0.25-0.75 on the drivers side front. I've put some contact cleaner in the connector, but I was thinking maybe I should remove the sensor and clean it up / clean up the mating faces / clean up the bore to see if that improves things?

*I use a cheap analogue multimeter for this kind of work (because it's easier to see the "swing") - but as it's all on one scale I can't work out if I'm looking at the wrong value.

Jakg · 19th October 2015, 13:41

I've cleaned the connector up, but it's still giving the lower voltage.

I've tried to remove the sensor, but I'm not confident that it will come out without breaking, so I am unable to clean it unless I'm confident thats the problem.

13th August 2015, 13:37	#64
HarryM1BYT This is my second home 75 Contemporary SE Mk II 2004 Man. Sal. CDTi 135ps, FBH on red diesel, WinCE6 DD Join Date: May 2010 Location: Leeds Posts: 17,273 Thanks: 2,160 Thanked 2,061 Times in 1,586 Posts	As per FrenchMikes suggestion, if it shows up on the road at low speed, it will definitely show up with the count and mark the pulse method, slowly rotating the wheel. The slower the wheel turns, the more susceptible it is to borderline pulses being missed by the ABS controller. The ultimate test for which, is rotating the wheel by hand and counting or marking on the tyre where the pulse occur. __________________ Harry How To's and items I offer for free, or just to cover the cost of my expenses... http://www.the75andztclub.co.uk/foru...40#post1764540 Fix a poor handbrake; DIY ABS diagnostic unit; Loan of the spanner needed to change the CDT belts; free OBD diagnostics +MAF; Correct Bosch MAF cheap; DVB-T install in an ex-hi-line system; DD install with a HK amp; FBH servicing. I've taken a vow of poverty. To annoy me, send money. Last edited by HarryM1BYT; 13th August 2015 at 13:40..

26th April 2014, 18:37	#61
Jakg This is my second home N/A Join Date: Feb 2010 Location: Suffolk Posts: 6,867 Thanks: 0 Thanked 397 Times in 302 Posts	Had another look today. Removed the hub (the hub nut wasn't on very tight...) and it looked quite dirty so cleaned it (and the sensor) up, but didn't make any difference. Replaced the hub (genuine MG Rover one off eBay for £80) and tested again and it worked fine. Replacing was much easier than I thought (although I had help!). Didn't need a new sensor after all so will return.

13th August 2015, 12:42	#62
Jakg This is my second home N/A Join Date: Feb 2010 Location: Suffolk Posts: 6,867 Thanks: 0 Thanked 397 Times in 302 Posts	Getting a similar problem again, where I can push the brake pedal about half way and then it gets "stuck" and won't go any further, as per ABS activation. I can reproduce this by applying constant brake pressure, slowing, then turning the car about 90°. I then can't brake much harder. It sounds like an odd way of driving, but there's a corner nearby that requires it which made me find it out! It also happens at low speeds very occasionally when turning and braking. I've pulled the ABS fuse and it doesn't seem to be happening any more. I don't think the problem is severe enough to be detected with the traditional "spin the wheels and count the pulses" approach? The front & rear passenger side hubs are both new.

27th September 2015, 20:13	#67
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: 11,579 Thanks: 3,470 Thanked 3,119 Times in 2,247 Posts	Is it missing at the same place every revolution? If so then it will be the bearing not the sensor.

18th October 2015, 17:07	#69
Jakg This is my second home N/A Join Date: Feb 2010 Location: Suffolk Posts: 6,867 Thanks: 0 Thanked 397 Times in 302 Posts	Replaced the passenger side sensor with one from DMGRS, which hasn't solved the problem, but it has solved the missing segment on the passenger side front. I've now tested all of the wheels and all segments are present and accounted for. I've tested again with the ABS fuse out and the issue goes away so it's definitely an ABS issue. The only oddity is that I don't seem to be getting the same output on the drivers side front - it alternates between 0.5-1* on all the other wheels, but between 0.25-0.75 on the drivers side front. I've put some contact cleaner in the connector, but I was thinking maybe I should remove the sensor and clean it up / clean up the mating faces / clean up the bore to see if that improves things? *I use a cheap analogue multimeter for this kind of work (because it's easier to see the "swing") - but as it's all on one scale I can't work out if I'm looking at the wrong value.

19th October 2015, 13:41	#70
Jakg This is my second home N/A Join Date: Feb 2010 Location: Suffolk Posts: 6,867 Thanks: 0 Thanked 397 Times in 302 Posts	I've cleaned the connector up, but it's still giving the lower voltage. I've tried to remove the sensor, but I'm not confident that it will come out without breaking, so I am unable to clean it unless I'm confident thats the problem.