Normal Operation
WARNING: This page is about a different car, the 2007 Lincoln MKX and 2007 Ford Edge. However, it is still accessible from the selected car via links, so may be relevant.
The status of the ABS system is sent to the instrument cluster from the ABS module over the high speed controller area network (HS-CAN) communication bus. The instrument cluster monitors the ABS input and illuminates the ABS warning indicator when a concern is present.
If the ABS message is missing for less than 5 seconds, the ABS warning indicator remains in the last indication mode (on or off). If the ABS message is missing for more than 5 seconds, the instrument cluster sets DTC U0121 in continuous memory and defaults the ABS and brake warning indicators on.
NOTE:
If the brake system experiences an EBD failure, both the brake warning indicator and the ABS warning indicators illuminate.
DTC U0121 - is a continuous memory DTC that sets in the instrument cluster if the ABS status message is missing from the ABS module for more than 5 seconds.
Possible Causes
- ABS module
- Instrument cluster