GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2001 🢒 Tracker - 4WD 🢒 Brakes 🢒 Antilock Brake System 🢒 DTC C1237

Circuit Description

DTC C1237 detects high vehicle voltage levels prior to any required motor movement (initialization or ABS). Damage to the system may occur if excessive voltage exists.

Conditions for Running the DTC

The vehicle speed is greater than 8 km/h (5 mph).

Conditions for Setting the DTC

A malfunction exists if the switched battery voltage is greater than 17 volts.

Action Taken When the DTC Sets
    • ABS is disabled.
    • The ABS warning indicator turns ON.

Conditions for Clearing the DTC
    • The condition responsible for setting the DTC no longer exists and the Scan Tool Clear DTCs function is used.
    • 100 drive cycles pass with no DTCs detected. A drive cycle consists of starting the vehicle, driving the vehicle over 16 km/h (10 mph), stopping and then turning the ignition OFF.

Diagnostic Aids

Thoroughly inspect the wiring and the connectors. An incomplete inspection of the wiring and the connectors may result in a misdiagnosis, causing a part replacement with the reappearance of the malfunction.

The following are possible causes of the malfunction:

    • A charging system malfunction.
    • An internal EBCM malfunction.

If an intermittent malfunction exists, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Test Description

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

  1. This step uses the scan tool to check the battery positive voltage circuit to the EBCM.

    2.

  2. This step checks the battery positive voltage supply circuit.

Step

Action

Value(s)

Yes

No

Schematic Reference: Antilock Brake System Schematics

1

Did you perform the ABS Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - ABS

2

  1. Turn OFF all of the accessories.
  2. Install a scan tool.
  3. Start the engine.
  4. Run the engine at approximately 2000 RPM.
  5. With a scan tool, observe the Switched Battery Voltage parameter in the ABS data list.

Does the scan tool indicate that the switched battery voltage is less than the specified voltage?

17 V

Go to Step 5

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the EBCM harness connector.
  3. Install the J 39700 using the J 39700-99 to the EBCM harness connector only.
  4. Start the engine.
  5. Run the engine at approximately 2000 RPM.
  6. Measure the voltage at the J 39700 between the battery positive voltage circuit of the EBCM and a good ground.

Does the voltage measure less than the specified value?

17 V

Go to Step 4

Go to Symptoms - Engine Electrical in Engine Electrical

4
  1. Use the scan tool in order to clear the DTCs.
  2. Carefully test drive the vehicle at a speed above 8 km/h (5 mph).

Does the DTC reset?

--

Go to Step 5

System OK

5

Replace the EBCM. Refer to Electronic Brake Control Module Replacement .

Did you complete the replacement?

--

Go to Step 6

--

6
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the conditions for Running the DTC as specified in the supporting test.

Does the DTC reset?

--

Go to Step 2

System OK