C0121

DTC C0121

Circuit Description
An internal solenoid valve relay in the Electronic Brake Control Module (EBCM)supplies battery positive voltage to all solenoid valves. This voltage is referred to as system voltage. The EBCM activates the solenoid valve relay when the ignition is turned ON. Once the solenoid valve relay has been activated, The EBCM supplies ground to actuate individual solenoid valves.

Conditions for Running the DTC
^ The ignition is ON.
^ Ignition voltage is greater than 8 volts.

Conditions for Setting the DTC
One of the following conditions exists for 0.23 seconds:
^ The EBCM commands the solenoid valve relay on and battery voltage is not present at the solenoid valves.
^ The EBCM commands the solenoid valve relay off and battery voltage is present at the solenoid valves.

Action Taken When the DTC Sets
If equipped, the following actions occur:
^ The EBCM disables the ABS/TCS/VSES for the duration of the ignition cycle.
^ ACC Braking is Degraded.
^ DRP is degraded.
^ The ABS indicator turns ON.
^ The Traction Control indicator turns ON.
^ The DIC displays the Service Stability System message.
^ The red Brake warning indicator turns ON.

Conditions for Clearing the DTC
^ The condition for the DTC is no longer present and the DTC is cleared with a scan tool
^ The electronic brake control module (EBCM) automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Diagnostic Aids
The system relay is integral to the EBCM. The relay is not serviceable.

Test Description
The number below refers to the step number on the diagnostic table.
2. Determines whether the DTC is current.

Steps 1 - 4:

DTC C0121