Trigger happy ABS!

Mgaz · 16th December 2020, 21:48

Has anyone experienced their ABS triggering when only slightly touching the brake pedal? And then eventually the ABS switches off entirely?

Any ideas what might be causing this?
Its a PITA because the car needs an MOT and this will probably cause a fail.

Car is a ZT 190 saloon

trikey · 17th December 2020, 07:20

Sounds like a rear wheel bearing issue to me.

vitesse · 17th December 2020, 07:46

Have a look at this recent thread -https://www.the75andztclub.co.uk/forum/showthread.php?t=303354

Regards

Lovel · 17th December 2020, 09:33

The magnetic ? Circular strip that provides the signal for the sensor can get damaged easily or perish over time leading to the symptoms you described. Mine turned out to be rear wheel failing, not the bearing but the strip. Had to purchase new bearing assembly and all good.

If opening up the rear brake shoes area remember to back off the adjusters or you will rip out the shoe locating pins from the probably well corroded brake backplate.

roverbarmy · 17th December 2020, 09:50

I remember reading about changing the brake fluid as old fluid can contaminate the ABS internals and cause sticking in the system. It's in my memory banks somewhere! ????

I also remember reading that the ABS needs bleeding with a T4. ???

This THREAD may help you? Post 22 may help in particular.

COLVERT · 17th December 2020, 12:02

The thing is that the OP says the system stops working altogether.---I don't think worn tyres would do that to it.--

marinabrian · 21st December 2020, 22:18

Quote:

Originally Posted by Lovel

The magnetic ? Circular strip that provides the signal for the sensor can get damaged easily or perish over time leading to the symptoms you described. Mine turned out to be rear wheel failing, not the bearing but the strip. Had to purchase new bearing assembly and all good.

If opening up the rear brake shoes area remember to back off the adjusters or you will rip out the shoe locating pins from the probably well corroded brake backplate.

Gary is spot on

The brake backplate has rusted and expanded where it is bolted to the stub axle on the trailing arm.

As the crusty part starts to touch the bearing oil seal, it wears through exposing the magnets embedded in the rubber, resulting in a plausibility issue.

The ABS modulator first sees this loss of signal as a stationary wheel and attempts to correct the problem as it would if the wheel was actually stationary.

This is experienced as low speed ABS actuation, and shortly after the fault first manifests the ABS light will come on until the next time the ignition is cycled.

New bearing will probably be required

Brian

16th December 2020, 21:48	#1
Mgaz Gets stuck in MG ZT190, MG ZS TD, MGF VVC, R200 TD bubble, Austin A35 Join Date: May 2017 Location: shrewsbury Posts: 648 Thanks: 530 Thanked 82 Times in 56 Posts	Trigger happy ABS! Has anyone experienced their ABS triggering when only slightly touching the brake pedal? And then eventually the ABS switches off entirely? Any ideas what might be causing this? Its a PITA because the car needs an MOT and this will probably cause a fail. Car is a ZT 190 saloon __________________ They say you should never meet your Idols. Well.... you know that car you always wanted? https://www.youtube.com/channel/UCGx...zZeAsYRU9aZu-A ^Be kind, Subscribe^ (MGR videos )

17th December 2020, 07:20	#2
trikey Premium Trader Rover 75 Join Date: Nov 2010 Location: Devon Posts: 33,756 Thanks: 8,837 Thanked 14,831 Times in 8,030 Posts	Sounds like a rear wheel bearing issue to me. __________________ Lest we forget..

17th December 2020, 09:33	#4
Lovel I really should get out more....... P6B, L550, Imp, F56, Commando Join Date: Nov 2006 Location: Aberdeenshire Posts: 2,886 Thanks: 352 Thanked 677 Times in 440 Posts	The magnetic ? Circular strip that provides the signal for the sensor can get damaged easily or perish over time leading to the symptoms you described. Mine turned out to be rear wheel failing, not the bearing but the strip. Had to purchase new bearing assembly and all good. If opening up the rear brake shoes area remember to back off the adjusters or you will rip out the shoe locating pins from the probably well corroded brake backplate. Last edited by Lovel; 17th December 2020 at 09:35..

17th December 2020, 09:50	#5
roverbarmy This is my second home Roverless + 1.7D Sportage Join Date: Aug 2014 Location: East Norfolk Posts: 7,048 Thanks: 729 Thanked 2,021 Times in 1,449 Posts	I remember reading about changing the brake fluid as old fluid can contaminate the ABS internals and cause sticking in the system. It's in my memory banks somewhere! ???? I also remember reading that the ABS needs bleeding with a T4. ??? This THREAD may help you? Post 22 may help in particular. __________________ Oil in my veins! Last edited by roverbarmy; 17th December 2020 at 09:55..

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17th December 2020, 07:46	#3
vitesse I really should get out more....... Rover 75 Saloon Join Date: Jul 2011 Location: Gävle Posts: 2,527 Thanks: 395 Thanked 823 Times in 652 Posts	Have a look at this recent thread -https://www.the75andztclub.co.uk/forum/showthread.php?t=303354 Regards

17th December 2020, 12:02	#6
COLVERT This is my second home R75 Saloon. Join Date: Feb 2009 Location: France/or Devon. Posts: 14,003 Thanks: 3,851 Thanked 2,167 Times in 1,816 Posts	The thing is that the OP says the system stops working altogether.---I don't think worn tyres would do that to it.--