TRACS/ABS: Anti Slip Service Required

[RoyMacDonald]

I got this error message coming up this week and so I took a trip to Charlewood Volvo who read the error codes and very quickly diagnosed a faulty ABS Yaw/Lateral Accelerator Sensor, and almost as quickly replaced it.

Not a cheap sensor though...£327 plus vat and the cost of fitting it. I opened up the old one to take a look and it looked like a small computer inside. A real quality piece of work is was too. You could have hung an elephant from the bracket that it was fixed to as well.

On the good side I did find out a lot about ABS. The XC90 has ABS version 8.1 Apparently earlier versions actually give increased breaking distances in ice, snow and poor traction surfaces like shale, gravel etc. Version 8.1 overcomes this and reduces them besides alowing you steer while breaking.

This type of system is going to be madatory from 2012 in the USA and the British Government is looking at a white paper about it at the moment. The accident reduction rate with this type of system fitted is amazing. 60% in Germany.

Here's a photo the 8.1 system components. The Yaw/Lateral Acceleration sensor is labled C

Thanks to Peter Suchy and co. at Charlwood Volvo for making it a quick and painless cure for my XC90.

Now I just have to convince Warranty Direct to pay up!!!

[Viper_7]

Originally Posted by RoyMacDonald

The XC90 has ABS version 8.1 Apparently earlier versions actually give increased breaking distances in ice

Pretty much all ABS systems have an increased stopping distance in snow/ice and quite often rain. Rather than the tyres digging in when braking/locking to a degree, they merely sit on the surface instead.

ABS does NOT shorten stopping distances in the majority of cases, all it allows is control of the vehicle.

Many people think hitting the brakes and allowing the ABS to do it's work will stop them the quickest - REMEMBER TO STEER OUT OF TROUBLE! It's tricky to do in an emergency situation, I'd recommend to all to practice on a private road/circuit.

Do you have a pic of the sensor/ and inards would be nice to see!
Was an expensive part though as you say!

Vipes

[RoyMacDonald]

Originally Posted by Viper_7

Pretty much all ABS systems have an increased stopping distance in snow/ice and quite often rain. Rather than the tyres digging in when braking/locking to a degree, they merely sit on the surface instead.

ABS does NOT shorten stopping distances in the majority of cases, all it allows is control of the vehicle.

Many people think hitting the brakes and allowing the ABS to do it's work will stop them the quickest - REMEMBER TO STEER OUT OF TROUBLE! It's tricky to do in an emergency situation, I'd recommend to all to practice on a private road/circuit.

Do you have a pic of the sensor/ and inards would be nice to see!
Was an expensive part though as you say!

Vipes

Hi Viper....The German test results I saw showed that ABS 2 and ABS 5.3 had increased stopping distance in ice and snow. ABS 8.3 had shorter and also was the only one that allowed the car to be steered at the same time.
8.1 makes 29 calculations a second and outperforms even the best professional race car drivers. I'd put the link up but I looked at so much stuff on ABS I can't remember where I saw the research.

Here are the photos...... or they would be, but I keep getting an web site dificulty page. Been trying for an hour, will try again tomorrow.

[RoyMacDonald]

Managed two but getting the error again.... all for now.

My car uses sensors made by Continental. (They do the OME tyres as well.) This is what they say about the sensor.


"The functioning of the Electronic Stability Control (ESC)* relies, among other things, on the sensory measurements of the vehicle's lateral acceleration and its rotation about its vertical axis (yaw rate). On four-wheel-drive vehicles an additional sensor has to monitor longitudinal acceleration. A reliable system solution for this is the sensor cluster. It combines a yaw rate sensor and the lateral acceleration sensor with a CPU and a CAN interface in a sturdy, torsion-resistant plastic housing. The cluster is mounted directly onto the vehicle. The housing design of the cluster guarantees that the sensor module is isolated from vibration and also provides optimum shielding from strong electromagnetic fields. Digitization of the measured signals and use of a CAN bus insure that no interference disrupts the transmission of the signals. The design concept of the cluster is modular and can be extended for the integration of additional sensor functions."

Notice that Volvo have specified an aluminium case instead of a plastic one.http://www.conti-online.com/generato...sp_movie_en.qt

There's a video of the system in operation at...

[RoyMacDonald]

I was reading the September issue of Land Rover monthly and found to my suprise a photo of the sensor on page 76, and also the Haldex transfer box. This is because the new Freelander 2 has the same 4 wheel drive system as the XC90.

Of course Ford still own both companies and I did know the new XC70 was getting the Land Rover hill descent control.

[RoyMacDonald]

Woops sorry about the slip up. I only just realised, it should be Anti SKID service.

[imotor]

I have a 2004 XC 90 and a BCM-0121 yaw rate sensor code. I read a tech bulletin that talked about a dampner. How will I know if I need the dampner or the actual sensor?

Thanks

[RoyMacDonald]

Originally Posted by imotor

I have a 2004 XC 90 and a BCM-0121 yaw rate sensor code. I read a tech bulletin that talked about a dampner. How will I know if I need the dampner or the actual sensor?

Thanks

Not sure what dampner your talking about. As far as I know there is nothing other than the sesors computers and ABS system and Haldax drive involved! Do you know which part of the system this dampener is in?

Your dealer should be able to work out which part is the problem from the Vardis error codes though.

Roy

[RoyMacDonald]

Just to add...the yaw sensor is very sensitive and delicate so I would suspect that first. Has to be very carefully handeld before it's put in the car.

Roy

[imotor]

This is the bulletin I was talking about. I appreciate your point on the sensitivity of the sensor itself. That is what I probably do. I do not have this code that the bulletin is talking about. However, is the yaw rate sensor a plug and play sensor, no coding involved?



2004 Volvo XC90 L5-2.5L Turbo VIN 59 B5254T2
Vehicle Level Brakes and Traction Control Technical Service Bulletins All Technical Service Bulletins ABS/TCS - Warning Lamp ON/DTC 0091 Set


ABS/TCS - Warning Lamp ON/DTC 0091 Set
Notes

NO: 59-14

DATE: 4-27-2007

MODEL: XC90

MODEL YEAR:
2003-2006

CHASSIS NO.
000690-298438

SUBJECT:
BCM DTC 0091, active yaw control sensor damper

REFERENCE:
VIDA

Description:

A customer may complain of a warning lamp or message on the instrument cluster, and fault tracing may find that BCM (Brake Control Module) DTC 0091 is set. The accelerometer within the active yaw control sensor is sensitive to vibrations and might set DTC 0091. This can occur for instance while driving on uneven roads or if the passenger seat is slammed backwards.

Service:







A vibration damper has been introduced from XC90 chassis no. 298439. If you have a customer complaint on vehicles within the chassis range indicated above, do not replace the active yaw control sensor. Install a vibration damper, part number 30773702 (# 1 in the illustration), on the sensor.

The damper has a self-adhesive strip on it which is how it is attached to the sensor.







WARRANTY CLAIM INFORMATION