Circuit Description
The system relay is energized when the ignition is ON. The system relay supplies voltage to the solenoid valves and the pump motor. This voltage is referred to as the system voltage.
The electronic brake control module (EBCM) controls each solenoid valve by grounding the solenoid.
The EBCM controls the pump motor by grounding the control circuit. The pump serves 2 purposes:
| • | Transfers brake fluid from the brake calipers to the master cylinder reservoir during pressure decrease events. |
| • | Transfers brake fluid from the master cylinder reservoir to the brake calipers during pressure increase events. |
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC C1214 System Relay Contact or Coil Circuit Open
Conditions for Running the DTC
| • | The ignition voltage is greater than 10.5 volts. |
| • | The system relay is commanded ON. |
| • | For Criteria 2, one of the following conditions exists: |
| - | The pump motor is OFF. |
| - | During initialization, the pump motor is ON. |
Conditions for Setting the DTC
One of the following conditions exists for 0.23 seconds:
Criteria 1
The system voltage is less than 8 volts.
Criteria 2
The difference between the ignition voltage and system voltage is greater than 1.9 volts.
Action Taken When the DTC Sets
| • | The EBCM disables the ABS for the duration of the ignition cycle. |
| • | The ABS 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.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Antilock Brake System Schematics | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
Does the DTC reset as a current DTC? | -- | Go to Step 3 | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | |
3 |
Does the DMM display the specified value? | OL | Go to Step 5 | Go to Step 4 |
4 | Replace the EBCM and the BPMV. Refer to Control Module References in Computer/Integrating Systems and Brake Pressure Modulator Valve Replacement . Did you complete the repair? | -- | Go to Step 6 | -- |
5 | Replace the EBCM. Refer to Control Module References in Computer/Integrating Systems. Did you complete the repair? | -- | Go to Step 6 | -- |
6 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
