ABS

[giusepppe]

Would a voltage of 12,27v across the battery terminal in the boot effect the performance of the wheel sensors ???. I have read in my manual to check the battery voltage if one is having problems with wheel sensors, has any body come across this advice.

 

[DSM10000]

Would a voltage of 12,27v across the battery terminal in the boot effect the performance of the wheel sensors ???. I have read in my manual to check the battery voltage if one is having problems with wheel sensors, has any body come across this advice.

What is the voltage with the engine running?

 

[giusepppe]

What is the voltage with the engine running?

I never thought of checking that, will have to have another look, although getting the back panel of in the boot of an S class is a real pain.

 

[giusepppe]

What is the voltage with the engine running?

I just checked the voltage with the engine running, it fluctuates between 14.17 to 14.2 volts, and 12.2 when not running

 

[Chrishazle]

Don't think battery voltage causes problems with wheel speed sensor, just had the "ABS Inoperative, consult owners manual" on my SLK, code reader said rear NS wheel speed snesor fault, had it replaced and code deleted, no more ABS warning on dashboard! However, you need a code reader that, like MB's Xentry system, will give full details of the fault and location. took mechain less than 1/2 hour to remove rear wheel, remove old sensor, install replacement, put wheel back on then use his code reader to clear the code and make sure it was working properly.

 

[giusepppe]

Don't think battery voltage causes problems with wheel speed sensor, just had the "ABS Inoperative, consult owners manual" on my SLK, code reader said rear NS wheel speed snesor fault, had it replaced and code deleted, no more ABS warning on dashboard! However, you need a code reader that, like MB's Xentry system, will give full details of the fault and location. took mechain less than 1/2 hour to remove rear wheel, remove old sensor, install replacement, put wheel back on then use his code reader to clear the code and make sure it was working properly.

I was fortunate to find someone who had a icarsoft V3 code reader, the two front sensors need replacing, which will be replaced when i get hold of them. and many thanks to all correspondents for your help.

 

[SpikyMikey]

Good to hear you solved your problem; just to flag up though that 12.2V resting is only about 60% charged.

 

[Petrol Pete]

As long as they have diagnosed that it is the sensors that are faulty and not the ring in the front wheel bearing that the sensor reads.

Also 2 sensors failing at exactly the same time ? Have you had any tyre/brake work done on the car recently ?

 

[giusepppe]

As long as they have diagnosed that it is the sensors that are faulty and not the ring in the front wheel bearing that the sensor reads.

Also 2 sensors failing at exactly the same time ? Have you had any tyre/brake work done on the car recently ?

Hi Pete, about a month ago, I replaced all the break pads, and the rear brake shoes, plus replaced the front offside wheel with the spare in the boot, as it got slightly buckled when I went over a large pot hole in Italy, which still needs repairing,
it might pay me also to check the continuity of the sensor before shelling out for new sensors, which are the Hall Effect type sensors, I believe the rear has the gear tooth pickup type sensor.

 

[Petrol Pete]

Depending on the car, putting a brand new tyre on one side matched to a worn one on the other side produces different wheel speeds which the 'computer' picks up as an anomaly and throws a fault.

I have personally had this happen on a new Vauxhall Vectra back in my company car days . I would imaging the ABS system on that car (1996 from memory) would have been pretty primitive by todays standards but if your fault appeared after the wheel change it might be something to keep in mind before paying for and fitting new parts.