GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1999 🢒 Tracker - 2WD 🢒 Brakes 🢒 Antilock Brake System 🢒 DTC C1242 Pump Motor Circuit Open

Object Number: 412173 Size: MF
ABS Components
Brake Pressure Modulator Valve (BPMV)

Circuit Description

The pump motor is an integral part of the Brake Pressure Modulator Valve (BPMV). The electronic brake control relay supplies power to the solenoid valves and pump motor. The electronic brake control relay, located in the EBCM, is activated whenever the ignition switch is in the ON position and no malfunctions are present. The electronic brake control relay remains engaged until the ignition switch is turned OFF or a malfunction is detected.

Conditions for Running the DTC
    • The switched battery voltage is greater than 8.0 volts.
    • The system relay is ON.
    • The pump motor is commanded OFF.

Conditions for Setting the DTC

DTC C1242 will set anytime the pump motor is commanded OFF. A DTC exists if the voltage across the pump motor is between 1.7 and 10.2 volts for 2.0 seconds.

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
    • Possible causes for DTC C1242 to set are:
       - The pump motor internals has an open.
       - The pump motor circuit is open.
    • The pump motor is an integral part of the BPMV and is not serviced separately.

Test Description

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

  1. This step uses the scan tool to test if the pump motor can be commanded ON and OFF.

    2.

  2. This step verifies the resistance of the pump motor.

    3.

  3. This step determines whether the DTC resets.

Step

Action

Value(s)

Yes

No

1

Did you perform the ABS Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - ABS

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With the scan tool, command the pump motor ON and OFF. This is done with the Pump Motor Test located in ABS Special Functions.

Does the pump motor turn ON and OFF with each command?

--

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Remove the EBCM from the BPMV.
  3. Measure the resistance between the pump motor control circuits.

Does the resistance measure less than the specified value?

5 ohms

Go to Step 4

Go to Step 6

4

  1. Use the scan tool in order to clear the DTCs.
  2. Use the scan tool in order to perform the Automated Test.

Does the DTC reset?

--

Go to Step 5

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

5

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

Did you complete the repair?

--

Go to Step 7

--

6

Replace the BPMV. Refer to Brake Pressure Modulator Valve Replacement .

Did you complete the repair?

--

Go to Step 7

--

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