GM Service Manual Online
For 1990-2009 cars only

Object Number: 393791  Size: MF
ABS Components
Antilock Brake System Schematics
Power Distribution Schematics
Power Distribution Schematics
Handling Electrostatic Discharge Sensitive Parts Notice

Circuit Description

The EBCM/EBTCM is required to operate within a specified range of voltage to function properly. The EBCM/EBTCM monitors for high voltage conditions which could damage the EBCM/EBTCM. This circuit is designed to detect high vehicle voltage levels to the solenoid relay. High voltage may cause damage to the system.

Conditions for Setting the DTC

DTC C1237 can only be set if the vehicle's speed is greater than 8 km/h (5 mph). If the battery voltage is greater than 17 volts, a malfunction exists.

Action Taken When the DTC Sets

    • A malfunction DTC is stored.
    • ABS/TCS is disabled.
    •  ABS/TCS Indicators are turned on.

Conditions for Clearing the DTC

    • Condition for DTC is no longer present and scan tool clear DTC function is used.
    • 100 ignition cycles have passed with no DTCs detected.

Diagnostic Aids

    • It is very important that a thorough inspection of the wiring and connectors be performed. Failure to carefully and fully inspect wiring and connectors may result in misdiagnosis, causing part replacement with reappearance of the malfunction.
    • If an intermittent malfunction exists refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
    • Check for other high voltage conditions.
    • Test the charging system for overcharging conditions. Refer to Charging System Check in Engine Electrical.

Test Description

The numbers below refer to step numbers on the diagnostic table.

  1. Checks to see what the EBCM/EBTCM is reading as the voltage.

  2. Checks the actual battery voltage.

DTC C1237 High System Voltage

Step

Action

Value(s)

Yes

No

1

Was the Diagnostic System Check performed?

--

Go to Step 2

Go to Diagnostic System Check - ABS

2

  1. Turn all accessories off.
  2. Start the engine.
  3. Using the scan tool select DATA LIST and monitor battery voltage while running engine at approximately 2000 RPM.

Is the voltage within the range specified in the Value(s) column?

Less than 17 V

Go to Step 4

Go to Step 3

3

Check actual battery voltage, using J 39200 DMM, while running engine at approximately 2000 RPM.

Is the voltage within the range specified in the Value(s) column?

Less than 17 V

Go to Step 4

Go to Charging System Check

4

  1. Use the scan tool to clear DTC.
  2. Carefully test drive vehicle above 8 km/h (5 mph).

Does DTC C1237 reset as a current DTC?

--

Go to Step 5

Go to Diagnostic System Check - ABS

5

Replace the EBCM/EBTCM. Refer to Electronic Brake Control Module/Electronic Brake and Track Control Module Replacement .

Is repair complete?

--

Go to Diagnostic System Check - ABS

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