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 C0116 can be set anytime.

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. Although the scan tool erases DTC C0116, the EBCM will keep the ABS indicator ON until the vehicle is driven 10 mph for at least 20 seconds, and the pump motor sends a proper monitor signal to the EBCM. Then the EBCM turns OFF the ABS indicator. If the pump motor monitor signal is still incorrect, DTC C0116 will set again as a current DTC and the ABS indicator remains ON.

Diagnostic Aids

Inspect the ABS fuse when diagnosing this part of the Antilock Brake System (ABS)

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. If the pump motor relay is stuck in the ON position, the pump motor will run all the time regardless of ignition switch position until the battery is dead.

  3. Test the pump motor by turning it on an off through a scan tool. The scan tool will display if the EBCM commands the pump motor ON and the feedback status.

Step

Action

Value(s)

Yes

No

1

Was the Diagnostic System Check performed?

--

Go to Step 2

Go to Diagnostic System Check

2

Turn the ignition switch to the LOCK position.

Is the BPMV pump motor still running?

--

Go to Step 5

Go to Step 3

3

  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.

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

--

Go to Step 6

Go to Step 4

4

  1. Disconnect the EBCM electrical connector.
  2. Using J 39200 DMM, measure the resistance between the EBCM electrical connector terminal C (harness side) and ground.

Is the resistance within the range specified in the value(s) column?

0-2 ohms

Go to Step 5

Go to Step 7

5

Replace the Brake Pressure Modulator Valve (BPMV) assembly. Refer to Brake Pressure Modulator Valve Assembly Replacement .

Is the repair complete?

--

Go to Diagnostic System Check

--

6

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

--

7

  1. Repair the open or high resistance in CKT 1150. Refer to Wiring Repairs in Wiring Systems.
  2. Clean and tighten G103.

Is the repair complete?

--

Go to Diagnostic System Check

--