GM Service Manual Online
For 1990-2009 cars only

Object Number: 221432  Size: MF
ABS Components
Antilock Brake System Schematics

Circuit Description

The pump motor relay is part of the Electronic Brake Control Module (EBCM). The EBCM turns ON and OFF the pump motor relay in order to activate the pump motor. The pump motor modulates the brake hydraulic pressure during an ABS stop.

Conditions for Setting the DTC

    • The Electronic Brake Control Module (EBCM) detects an open in the pump motor circuitry.
    • DTC C0114 can be set anytime the pump motor is actuated.

Action Taken When the DTC Sets

    • A malfunction DTC stores.
    • The ABS disables.
    • 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. If the pump motor monitor signal is still incorrect, DTC C0114 will set again as a current DTC and the ABS indicator remain ON.

Diagnostic Aids

Inspect the following list of items when diagnosing this part of the Antilock Brake System (ABS):

    • The ABS fuse.
    • Open or high resistance in the pump motor input circuit (CKT D).

Inspect the harness connectors for the following conditions:

    • Backed-out terminals
    • Improper mating
    • Broken locks
    • Improperly formed or damaged terminals
    • Poor terminal to wiring connections or physical damage to the wiring harness

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

  1. The Diagnostic System Check must be the starting point for any ABS related diagnosis.

  2. Test the pump motor by turning it on and off through a scan tool. The scan tool will display if the Electronic Brake Control Module (EBCM) commands the pump motor ON and feedback status.

  3. Test for an open or high resistance in the motor power input circuit (CKT 642).

Step

Action

Value(s)

Yes

No

1

Was the Diagnostic System Check performed?

--

Go to Step 2

Go to Diagnostic System Check

2

  1. Connect a scan tool to the Data Link Connector (DTC).
  2. Turn the ignition switch to the ON position.
  3. Select Diagnostic Trouble Codes (DTC) on the scan tool.
  4. Select Clear DTC Information on the scan tool.
  5. Select Special Functions from the Application Menu on the scan tool.
  6. Select Device Control on the scan tool.
  7. Command the pump motor ON with the scan tool.

Did the scan tool display pump motor command ON and monitor ON during this test?

--

Go to Step 4

Go to Step 3

3

  1. Turn the ignition switch to the LOCK position.
  2. Disconnect the EBCM electrical connector.
  3. Connect J 39200 DMM between the EBCM electrical connector terminal D (harness side) and ground.
  4. Use J 39200 DMM in order to measure the voltage.

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

Battery Voltage (10-14 V)

Go to Step 5

Go to Step 6

4

A malfunction is not present at this time. Refer to Diagnostic Aids for additional information regarding this DTC.

Is the action complete?

--

Go to Diagnostic System Check

--

5

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

Is the repair complete?

--

Go to Diagnostic System Check

--

6

Repair the open or a high resistance in CKT 642.

Is the repair complete?

--

Go to Diagnostic System Check

--