C1218

DTC C1218: ABS Relay Coil Circuit Shorted To Voltage:

DTC C1221: Left Front Wheel Speed Sensor Schematic:

DTC C1218 Schematic:

Circuit Description
Ignition voltage is supplied to terminal 85 of the ABS relay. The Electronic Brake Control Module (EBCM) is then able to energize the pull-in coil by completing the ground circuit at EBCM connector C1 terminal D6. The magnetic field created closes the ABS relay contacts and allows battery voltage and current to be supplied to the EBCM. In addition, the EBCM supplies power to the motors and the ABS solenoids.

Conditions for Setting the DTC
This DTC will set when the following conditions are met:
^ This test checks for a short to battery voltage in the ABS relay control circuit (CKT 879), causing the ABS relay to remain OFF all the time.
^ This DTC can be set anytime.

Action Taken When the DTC Sets
A malfunction DTC is stored, ABS is disabled, and the amber ABS indicator lamp is turned ON. The red BRAKE warning lamp is turned ON if the rear piston in the motor pack is not expected to be in the home position.

Conditions for Clearing the DTC
^ Conditions for the malfunction are no longer present and the Tech 2 scan tool Clear DTC Information function is used.
^ One hundred drive cycles have passed with no malfunctions detected.

Diagnostic Aids
The following list contains items that need to be inspected when diagnosing this system:
^ Short to battery voltage in CKT 879.
^ Faulty ABS relay (low or no coil resistance).
The frequency of the malfunction can be checked by using the Enhanced Diagnostic function of the Tech 2 scan tool, as described in Enhanced Diagnostics.

Inspect the following harness connectors for improperly formed or damaged terminals before component replacement:
^ EBCM connector C1.
^ ABS relay harness connector terminals.


Test Description
The numbers below refer to step numbers on the diagnostic table.
2. Checks voltage input to the EBCM (CKT 850) when commanding ABS relay ON.
3. Check for short to voltage in CKT 879.
4. Confirms if this DTC resets after 2 drive cycles.