My 2019 S Max has developed a fault that's gradually happening more where it throws up a warning on the dash for the traction control+hill start+ESC control+ABS etc etc that stops working unless it's either switched off or just driving it sometimes clears the fault. Ford said it had a fault code for the N/S/F ABS sensor fault, they recommended changing both sides for £230?! My question is, on this model is it an ABS sensor wire which just reads off the CV joint or is it an ABS hub that's fitted? Another Ford dealer said its a complete hub, but having just taken a wheel off it looks to be just a bolt in sensor, in which case it's very easy to change myself. Thanks for any help.

Check your car battery voltage with a multimeter about 1 hour after parking. Is the State Of Charge low. 50% or less?

Thanks for your reply Unofix.

Checking it tonight, 30 minutes after it was stopped it was 12.20, so easily getting on for 50%.

The stop/start hasn't worked for a good while, but apart this ABS issue, it's been OK.

 Would you think low battery voltage would throw up an ABS fault? Wouldn't the fact its running and charging override any low battery voltage?

2 hours ago, jimmy71 said:

Wouldn't the fact its running and charging override any low battery voltage?

You would think so, but it doesn't. The smart charge system (not very smart) often limits or disables equipment even when the car is running. It's a well known issue that some automatic gearboxes will preform very badly if the battery voltage is low, the same for EPAS.

Hill Start Assist, or Auto Hold is always disabled if battery voltage is low because the ABS pump needed for those systems uses a lot of power in order to hold the brakes on.

OK, that makes sense. As the cheaper option I'll go with a battery, its obviously past its best. Does the BCM need to be reset in someway, or does it recognise a new battery is fitted?

Before fitting the new battery, it should ideally be charged for 12 hours. Even if it is supplied charged.

Fit the new battery and then reset the Battery Monitoring System (BMS) using the following method:

On 3/29/2023 at 8:14 PM, unofix said:

How to reset the BMS method 2

 

 

Thanks for your help. Much appreciated.