Sunday, 8 June 2014

Ford Fiesta ABS Light Stays On


The ABS warning light lit up continuously on my daughters Ford Fiesta Style 2005 plate.


ABS Symbol


After a bit of Googling (other search engines are available) to see what the fault could be and narrow down my search area. I finally got around to taking each wheel off in turn and checking the wheel speed sensors for damage. I found the drivers side front wheel speed sensor's wire insulation nearest the inside of the wheel arch had worn away exposing the copper wires inside, it had also worn away one of the wires. The sensor wire wearing away may have been due to a broken suspension spring that occurred a while before the ABS fault, the spring was replaced a while back. As a test repair I soldered the broken wires of the sensor back together and switched on the ignition but the ABS light stayed on. Disappointed I drove down our private road and after driving about 30 feet the light went out, yeehaa! (this is me happy). Apparently from what I have read the ABS light will stay on even after a sensor repair until the ABS system detects pulses coming in from the sensor after the vehicle is in motion, only then will the light go out.  I ordered and fitted a new sensor cable assembly to replace the temporarily repaired one as I didn't want to take chances with a repair on the ABS system, the ABS light has stayed out ever since.
If you undertake any work, be safe, remember cars are heavy, tools are dangerous if used incorrectly, you are responsible for your own actions.
UPDATE:
I bought one of these F-Super Diagnostic USB dongles to read the fault codes and reset the fault on the ABS ECU.
F-Super Diagnostic Dongle
I installed the drivers and the software onto my laptop, plugged in the usb. I then plugged in the dongle to the OBD connector on the Fiesta, it is located at the bottom of the Steering column cover under a little flap. The software was run and the fault code read it was indeed signal loss from a wheel sensor. I wish I had this device before, so I knew what I was looking for when trying to fault find.
I also reset the fault code on the ABS ECU so if the error comes back I'll know.

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