C1236

DTC C1236





Circuit Description
The electronic brake control module (EBCM) monitors the voltage level available for system operation. A low voltage condition prevents the system from operating properly.

DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC C1236 Low System Supply Voltage

Conditions for Running the DTC
^ The vehicle speed is greater than 8 km/h (5 mph).
^ The ignition voltage is less than 10.8 volts.
^ The system relay is commanded ON.

Conditions for Setting the DTC
One of the following conditions exists for 0.72 seconds:
^ During initialization or when the system is inactive, the system voltage is less than 10.8 volts.
^ During the system operation, the system voltage is less than 9.36 volts.

Action Taken When the DTC Sets
If equipped, the following actions occur:
^ The EBCM disables the antilock brake system (ABS) for the duration of the ignition cycle.
^ The EBCM disables the TCS (w/NW9) for the duration of the ignition cycle.
^ The dynamic rear proportioning (DRP) does not function optimally, or with ignition voltage less than 8.5 volts, the EBCM disables the DRP for the duration of the ignition cycle.
^ The ABS indicator turns ON.
^ The Traction Off 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 EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Diagnostic Aids
^ Test the charging system. Refer to Diagnostic System Check - Vehicle.
^ Possible causes of this DTC are the following conditions:
^ A charging system malfunction
^ An excessive battery draw
^ A weak battery
^ A faulty system ground

Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. Use the scan tool in order to inspect the voltage to the EBCM.
3. Use the scan tool in order to inspect the voltage to the body control module. A low voltage value in multiple modules indicates a concern in the charging system.
5. Verifies that the condition is still present.