Wheels off ground!

ryszard · 13th March 2017, 20:06

Hi,as mentioned before on the way to the MOT I had an ABS judder at low speed,after passing the MOT it constantly has traction control warning and ABS warning,would the MOT procedure put stress on the system to activate the warnings constantly.The warnings come up with the ignition without driving.Have been round and cleaned sensors and bearings,today I jacked the front of the car up and and put it into drive,still ABS judder at low speed,speedo works so I presume it could be the front nearside sensor,I then got above 30 mph and put cruise control on,my question should the cruise stay constant despite the wheels having no road contact as I noticed it sped up became erratic and the cruise disengaged.So can anyone confirm if cruise should work as normal with the front wheels off the ground.Its a launch car.This would help me narrow down the sensor options before getting too technical and putting multimeter and checking signals,which I am not too good at.Checked the traction control gear mechanism on the bulkhead,activates OK.Cleaned all connections on throttle body. Regards Ryszard...

Robson Rover Repair · 13th March 2017, 20:31

Do you have marching tyre profiles on each wheel?

First port of call before anything else.

rab60bit · 13th March 2017, 21:50

Quote:

Originally Posted by Colin_NI

Do you have marching tyre profiles on each wheel?

First port of call before anything else.

Is that marching

tyre profiles with "cat like tread"

(due acknowledgement to Messrs. Gilbert and Sullivan)

RogerHeinz57 · 13th March 2017, 21:53

Hi Richard, the system won't allow you to test in such a fashion, from experience, small tyre size variation is unlikely to bother the system too much otherwise the problem would have manifest itself on the way to the test station not straight afterwards.
I have made an in-line plug in test lead which will require the use of a multi meter to read signals during wheel rotation and white chaly each gap in signal on the tyre. This will ascertain a signal drop or no signal at all on the affected corner. Even a VT-4 system only allows a certain speed to be reached before it cannot do accurate measurements.
Furthermore, Does the system have a constant ABS light showing with key in position 2 or does it go out, then come back on ?
In other words, does it pass the static test ?
Also, if the car is driven, does the cruise control activate and keep the car at the pre-determind speed?
The answers to these questions should point us in a direction before spending £ on guesswork.

Chat soon matey !

ryszard · 13th March 2017, 23:24

Hi,yes matching tyres,never had a problem till after the MOT.
Yes J,have constant ABS warning on all the time before starting the engine.Due to 'man flue' but now better have not yet driven it on the road to see if cruise control works as it should.Will probably do that later today.You may get a phone call from me.Is it OK to take for a drive with these warnings or could it shut down or go into some sort of safe mode?Regards Ry......

thundercat · 14th March 2017, 06:16

Excuse my ignorance but what is "traction control" and what 75 have this fitted, I understand ABS

Jakg · 14th March 2017, 07:44

Quote:

Originally Posted by ryszard

my question should the cruise stay constant despite the wheels having no road contact as I noticed it sped up became erratic and the cruise disengaged

This is normal. If the system detects sudden deceleration (not that word again!) or acceleration beyond a certain threshold it cuts out.

In a powerful RWD car, if you went through standing water and the car started to slow, if the car just kept putting more and more power into the back wheels to keep the speed up things would get very bad.

KWIL · 15th March 2017, 11:06

Thundercat.

Traction Control is an option. The system compares the relative rotation of the driven wheels and reduces the power when one is slow, ie inside wheel on a very sharp turn, or when one spins up due to lack of adhesion. Brake is applied to the fast wheel and engine power reduced. All via special ABS unit + ECU

ryszard · 16th March 2017, 00:14

KWIL,well described.Better explanation than I was about to put.Traction control was also an option,mainly on V6.I have a launch car so was standard.Still working on my problem!Regards Ry..

13th March 2017, 20:06	#1
ryszard Gets stuck in Moonstone diesel,X351 Jaguar and now MG ZT 260 Join Date: Dec 2013 Location: Northampton Posts: 682 Thanks: 288 Thanked 118 Times in 96 Posts	Wheels off ground! Hi,as mentioned before on the way to the MOT I had an ABS judder at low speed,after passing the MOT it constantly has traction control warning and ABS warning,would the MOT procedure put stress on the system to activate the warnings constantly.The warnings come up with the ignition without driving.Have been round and cleaned sensors and bearings,today I jacked the front of the car up and and put it into drive,still ABS judder at low speed,speedo works so I presume it could be the front nearside sensor,I then got above 30 mph and put cruise control on,my question should the cruise stay constant despite the wheels having no road contact as I noticed it sped up became erratic and the cruise disengaged.So can anyone confirm if cruise should work as normal with the front wheels off the ground.Its a launch car.This would help me narrow down the sensor options before getting too technical and putting multimeter and checking signals,which I am not too good at.Checked the traction control gear mechanism on the bulkhead,activates OK.Cleaned all connections on throttle body. Regards Ryszard...

13th March 2017, 20:31	#2
Robson Rover Repair NI/ROI RS ZT-T 190 / 75 Diesel x3 / 6 door limo / 216 Cabby / Rover 25 van Join Date: May 2009 Location: Antrim Posts: 8,101 Thanks: 299 Thanked 1,046 Times in 568 Posts	Do you have marching tyre profiles on each wheel? First port of call before anything else. __________________ Cheers, Colin Robson Rover Repair on Youtube DISCOUNTED MTEC BRAKES FOR ALL MG ROVER'S Braided hoses, more coating and pad options for 2024

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

13th March 2017, 21:53	#4
RogerHeinz57 I really should get out more....... A Reasonably Priced Car Join Date: Jan 2014 Location: Burton Latimer Posts: 2,530 Thanks: 408 Thanked 1,064 Times in 712 Posts	Hi Richard, the system won't allow you to test in such a fashion, from experience, small tyre size variation is unlikely to bother the system too much otherwise the problem would have manifest itself on the way to the test station not straight afterwards. I have made an in-line plug in test lead which will require the use of a multi meter to read signals during wheel rotation and white chaly each gap in signal on the tyre. This will ascertain a signal drop or no signal at all on the affected corner. Even a VT-4 system only allows a certain speed to be reached before it cannot do accurate measurements. Furthermore, Does the system have a constant ABS light showing with key in position 2 or does it go out, then come back on ? In other words, does it pass the static test ? Also, if the car is driven, does the cruise control activate and keep the car at the pre-determind speed? The answers to these questions should point us in a direction before spending £ on guesswork. Chat soon matey !

13th March 2017, 23:24	#5
ryszard Gets stuck in Moonstone diesel,X351 Jaguar and now MG ZT 260 Join Date: Dec 2013 Location: Northampton Posts: 682 Thanks: 288 Thanked 118 Times in 96 Posts	Hi,yes matching tyres,never had a problem till after the MOT. Yes J,have constant ABS warning on all the time before starting the engine.Due to 'man flue' but now better have not yet driven it on the road to see if cruise control works as it should.Will probably do that later today.You may get a phone call from me.Is it OK to take for a drive with these warnings or could it shut down or go into some sort of safe mode?Regards Ry......

14th March 2017, 06:16	#6
thundercat Posted a thing or two Rover 75 Club SE Join Date: Jul 2012 Location: saxmundham Posts: 1,438 Thanks: 289 Thanked 173 Times in 121 Posts	Excuse my ignorance but what is "traction control" and what 75 have this fitted, I understand ABS

15th March 2017, 11:06	#8
KWIL Precise Rover 75 Tourer 2.5KV6 Connoisseur SE Join Date: Mar 2013 Location: Fleet Posts: 2,952 Thanks: 630 Thanked 617 Times in 480 Posts	Thundercat. Traction Control is an option. The system compares the relative rotation of the driven wheels and reduces the power when one is slow, ie inside wheel on a very sharp turn, or when one spins up due to lack of adhesion. Brake is applied to the fast wheel and engine power reduced. All via special ABS unit + ECU

16th March 2017, 00:14	#9
ryszard Gets stuck in Moonstone diesel,X351 Jaguar and now MG ZT 260 Join Date: Dec 2013 Location: Northampton Posts: 682 Thanks: 288 Thanked 118 Times in 96 Posts	KWIL,well described.Better explanation than I was about to put.Traction control was also an option,mainly on V6.I have a launch car so was standard.Still working on my problem!Regards Ry..