3 Series & 1 Series BMW rear pad service light problem

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

BMW E46 missing mpg and cruise control fault

I was called out today to a local garage customer to help solve an issue with his 2001 BMW E46 that he had purchased, he was having issues with the cruise control light stuck on and cruise control function not working, other faults also included the trip information in the digital display not working, the only read out the car had was time, you couldn’t scroll through and select MPG or trip distance etc.
Before I got involved the customer had already sent the dash / ECU away and had it checked and the company checking it had come to the conclusion that there was an internal fault, upon receiving this information the customer purchased a new dash but the faults remained.
I plugged my Delphi DS150E in to the car and performed a global scan and a few faults where presented, 1 was a steering angle fault (indicated by the yellow triangle with arrow round on the dash) , there where various other faults that manly related to the battery going flat at some point and we also had a fault code in the instrument cluster 8c Terminal R fault which was a current stored code in the ECU and wouldn’t clear.

First of all I dealt with the steering angle fault and re-calibrated the steering angle sensor using the Delphi and the light went off and I cleared the fault  out of the ECU. Now to try and deal with the cruise control problem and the missing info in the trip computer.
Neither issues where bringing up a fault code so where unlikely to be at fault so the fault must have been else where. Through live data I checked the cruise control buttons on the steering wheel and could see that the switches where working fine as we could read the on/off information from the ECU.

So what was this 8c Terminal R fault? this must have something to do with the problems, but where??
After a bit of thought and a bit of reading up, I found that the Terminal R fault relates to a problem with a below 12v supply being fed to the dash, first place to check was the fuse box, fuse number 10 relates to the cruise control and trip info on the dash and guess what!!! the fuse was missing, replaced the fuse on the board turned the ignition on and hey presto, cruise control light was no longer stuck on and we could select through all of the options on the trip computer. A quick scan back in the instrument cluster and erase the terminal R code and the BMW is now working fine and the dash is no longer lit up like a Christmas tree.

I believe the garage will be phoning the company that tested the original dash to find out how they came to the conclusion that it was fried when it wasn’t the problem in the first place.

Ian Burt
Motor Serv Garage Equipment
www.msge.co