Have you had problems turning out the service light after changing the rear pads on a BMW 1 or 3 Series?
I have come across this fault on 4 or 5 occasions now, mostly on the 3 series BMW’s but I have also had 1 case on a 1 series BMW.
So, I usually get a call from a garage asking for help, they have changed the rear brakes on one of these cars and now they can’t clear the service light, can I help?
The first time I came across this problem I was a bit stumped but figured it out after a while. It turns out that these cars have a bit of a glitch in the system and it can be rectified fairly easily with the right diagnostic equipment, for this I use the Delphi DS150E .
What normally happens is the pads are changed and you end up not being able to reset the service light and normally end up with the ABS light on with fault codes stored, these fault codes are normally 1 or both of the following:
• 5DE0 Brake-pad wear: plausibility, front axle
• 5DE1 Brake-pad wear: plausibility, rear axle
You are also likely to see on the diagnostic tool when trying to reset the CBS (condition based servicing) for the rear pads a strange percentage for the next availibility factor and it normally displays 255% when this glitch occurs
(A common error that I have seen is that a garage will then change the sensors and it will not rectify the problem and then the car gets sent to the dealer.)
What actually happens in these cases is that the ECU loses it memory for the front brake pads, and throws up this plausibility fault.
So how do we get round this problem / glitch. Its a fairly simple fix and can be done with tools like the Delphi DS150E. The diagnostic tool needs to be able to perform a CBS Correction, in CBS (Condition Based Service) correction you need to go in to front pads and from there you need to tell the ECU what service you want the front pads to be on and then you need to tell the ECU the thickness of the front pads in mm, you can either measure the pads or keep trying different thicknesses ie 6mm, 8mm, etc until you get the correct thickness (it will only work once the right thickness is input), once this has been successfully completed the plausibility fault codes will clear and you can now go back in to the CBS reset for the rear pads and reset the service.
Ian Burt
Motor Serv Garage Equipment
www.msge.co
Motor Serv Garage Equipment 