Brake warning lights
Q
A new problem with my wife’s 2002 MINI Cooper. It’s intermittently displaying the handbrake light, ABS and ASC+T (traction control). Initially I considered an ABS sensor problem but apparently the speedo is working normally.
I’ve not experienced the fault myself but thought I would monitor the ABS sensor outputs on a meter – however the front sensor cables disappear underneath the wheelarch liners which I guess is where I would find the connectors. Job for a dry day. Once again I find the Haynes manual woefully lacking in the wiring section as I was hoping to trace cabling back to the ABS unit. Am I looking in the right direction do you think, I’m hoping it’s something simple!
Also is there a plug-in diagnostic device that could help with similar problems? I have a cheap Foxwell unit which is OK for engine sensors but not body components.
Alan Worland
A
To read the ABS systems the Foxwell NT 530 Full Systems Scan Tool - BMW & MINI at £164 would cover the ABS system and read-off any faults in the Abs/traction system. It is possible that the fault is a speed sensor but it is also possible that the problem is in the module, and these were known to develop problems. The ABS unit and module are combined and may give off a code such as 5DF5 indicating ABS Control Unit Internal Fault or may give off speed sensor fault codes. In this instance a repair of the unit would be the best option. Try ECU Testing for advice at ecutesting.com
The speedo would not necessarily stop operating if one of the speed sensors failed, but the light would normally flag-up or be on permanently.
The sensor wires do connect up under the wheelarch liners and should run into a small box with the connector enclosed in the box. They are difficult to access and the inner wheelarches do need to be released to gain access.
It is possible to check the sensors using a meter by spinning the wheel slowly, the reading should be in the region of 4ma or 9ma switching as the wheel is turned.
Other than checking the speed sensor connection plugs and outputs, it would also be worth checking that the ABS module plug is clean and that there is no corrosion on any of the terminals.