GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The pump motor is contained within the brake pressure modulator valve (BPMV). The pump motor ground is supplied through terminal 15 of the electronic brake control module (EBCM).

Conditions for Setting the DTC

DTC C0042 can only be set with the key in the ON position, the pump motor is OFF, and the EBCM detected high resistance or an open circuit across the motor.

Action Taken When the DTC Sets

    • The solenoid relay opens, removing voltage from the solenoids and pump motor.
    • DTC C0042 is stored
    • ABS disabled, ABS warning lamp turns ON.

Conditions for Clearing the DTC

    • If the conditions that set DTC C0042 are no longer present, the DTC may be cleared by using the proper scan tool.
    • The DTC that has not occurred in 100 drive cycles will be cleared from history data.

Diagnostic Aids

Typical causes for DTC C0042:

    • BPMV pump motor open or high resistance
    • EBCM malfunction

Step

Action

Values

Yes

No

1

Did you perform the Diagnostic System Check-ABS?

--

Go to Step 2

Go to Diagnostic System Check - ABS

2

  1. Turn the ignition switch to OFF.
  2. Disconnect the EBCM.
  3. Remove the EBCM from the BPMV.
  4. Inspect the EBCM to BPMV connector for conditions such as damage corrosion, poor terminal contact, or the presence of brake fluid.

Were the terminals and connector OK, and the cavity free of brake fluid, damage, and corrosion?

--

Go to Step 4

Go to Step 3

3

  1. If damage and/or corrosion are present, replace the EBCM and/or the BPMV as necessary. Refer to Brake Pressure Modulator Valve Assembly Replacement .
  2. If the brake fluid is present, replace both the EBCM and the BPMV. Refer to Brake Pressure Modulator Valve Assembly Replacement .

Did you complete the replacement?

--

System OK

--

4

Connect an ohmmeter to terminal 1 and terminal 2 of the BPMV.

Was the pump motor resistance reading less than specified value?

2 ohms

Go to Step 6

Go to Step 5

5

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

Did you complete the replacement?

--

System OK

--

6

Replace the EBCM. Refer to Brake Pressure Modulator Valve Assembly Replacement .

Did you complete the replacement?

--

System OK

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