Circuit Description
The electronic brake control module (EBCM) monitors the voltage level available for system operation. If the voltage level is too high, damage may result in the system. When the EBCM detects a high voltage condition, the EBCM turns OFF the system relay which removes battery voltage from the solenoid valves and pump motor.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC C1237 High System Supply Voltage
Conditions for Running the DTC
The vehicle speed is greater than 8 km/h (5 mph).
Conditions for Setting the DTC
The system voltage is greater than 17 volts for 0.7 seconds.
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 traction control system (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
A possible cause of this DTC is overcharging.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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Use the scan tool in order to inspect the voltage to the EBCM.
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Use the scan tool in order to inspect the voltage to the body control module. A high voltage value in multiple modules indicates a concern in the charging system.
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Verifies that the condition is still present.
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 scan tool indicate that the voltage is greater than the specified value? | 16.3 V | Go to Step 3 | Go to Diagnostic Aids | |
With a scan tool, observe the Battery Voltage parameter in the Body Control Module data list. Does the scan tool indicate the voltage is greater than the specified value? | 16.3 V | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | Go to Step 4 | |
Does the DTC reset? | -- | Go to Step 5 | Go to Diagnostic Aids | |
5 | Replace the electronic brake control module (EBCM). Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the repair? | -- | Go to Step 6 | -- |
6 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
