GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2008 🢒 Vibe - FWD 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 DTC C1241

Circuit Description

The electronic brake control module (EBCM) monitors the ignition positive voltage level available for Antilock Brake System (ABS) operation.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC C1241 ECU Voltage

Conditions for Running the DTC

The vehicle speed is greater than 3 km/h (2 mph).

Conditions for Setting the DTC
    • The ignition positive voltage is less than 9.5 volts for 10 seconds.
    • The battery positive voltage is greater than 19 volts for 1 second.

Action Taken When the DTC Sets
    • The ABS is disabled.
    • The ABS warning indicator turns ON.
    • The traction control and vehicle stability control (VSC) is disabled, if equipped.
    • The VSC warning indicator turns ON, if equipped.

Conditions for Clearing the DTC

The condition responsible for setting the DTC no longer exists and the scan tool Clear DTCs function is used.

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:

    • Low battery voltage
    • High battery voltage
    • An open or high resistance in the ignition positive voltage circuit
    • An open or high resistance in the EBCM ground circuits
    • An internal EBCM malfunction

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

Test Description

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

  1. This step tests the ignition positive voltage circuit.

    2.

  2. This step tests the EBCM ground circuits for a high resistance or an open.

Step

Action

Value(s)

Yes

No

Schematic Reference: Antilock Brake System Schematics

Connector End View Reference: Antilock Brake System Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

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Go to Step 2

Go to Diagnostic System Check - Vehicle

2
  1. Turn OFF all of the accessories.
  2. Start the engine.
  3. Measure the battery voltage.

Is the voltage as specified?

11-14 V

Go to Step 3

Go to Symptoms - Engine Electrical

3

  1. Turn OFF the ignition.
  2. Disconnect the electronic brake control module (EBCM) harness connector.
  3. Turn ON the ignition.
  4. Measure the voltage between the ignition positive voltage circuit of the EBCM and a good ground.

Is the voltage as specified?

10-14 V

Go to Step 5

Go to Step 4

4

Locate and repair the following in the ignition positive voltage circuit of the EBCM.

    • An open
    • High resistance
    • Short to ground

Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 7

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5

Test the EBCM ground circuits for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 7

Go to Step 6

6

Replace the brake pressure modulator valve (BPMV). Refer to Brake Pressure Modulator Valve Assembly Replacement .

Did you complete the replacement?

--

Go to Step 7

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7
  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 text.

Does the DTC reset?

--

Go to Step 2

System OK