GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2004 🢒 Rainier 🢒 Brakes 🢒 Antilock Brake System 🢒 DTC C0201

Circuit Description

The system relay, located within the electronic brake control module (EBCM), supplies battery voltage to all of the valve solenoids and to the ABS pump motor. When the relay contacts close, the EBCM monitors the voltage supplied to the valve solenoids and compares this voltage to monitored ignition voltage.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

The EBCM detects that the voltage supplied to the valve solenoids is less than 80% of monitored ignition voltage for 50 milliseconds.

Action Taken When the DTC Sets
    • The EBCM disables the ABS/DRP.
    • The ABS indicator turns ON.
    • The brake warning indicator turns ON.

Conditions for Clearing the DTC

The Conditions for Setting the DTC are no longer present and you use the scan tool Clear DTCs function.

Diagnostic Aids

Refer back to the diagnostic table, steps 3 through 7, if this DTC continues to set intermittently.

Test Description

The number below refers to the step number on the diagnostic table.

  1. A shorted ABS pump motor may damage the contacts within the system relay. It is imperative that the steps in the table be followed to prevent damage to a replacement EBCM.

Step

Action

Values

Yes

No

Schematic Reference: Antilock Brake System Schematics

1

Did you perform the ABS Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - ABS

2
  1. Use a scan tool in order to clear the DTCs.
  2. Use the scan tool in order to perform an ABS Function Test.

Does the DTC set?

--

Go to Step 3

Go to Diagnostic Aids

3

  1. Separate the EBCM from the BPMV. Refer to Electronic Brake Control Module Replacement .
  2. Use a DMM in order to measure the resistance across the ABS pump motor.

Does the resistance measure within the specified range?

0.3-1.0 ohms

Go to Step 4

Go to Step 6

4

Use a DMM in order to measure the resistance between the high side of the pump motor and a good ground.

Does the resistance measure less than the specified value?

0L

Go to Step 6

Go to Step 5

5

Important: Following EBCM replacement, use the scan tool to perform the Tire Size Calibration procedure.

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

Did you complete the replacement?

--

Go to Step 7

--

6

Important: Following EBCM replacement, use the scan tool to perform the Tire Size Calibration procedure.

Replace the EBCM and the BPMV. Refer to Electronic Brake Control Module Replacement and Brake Pressure Modulator Valve Replacement .

Did you complete the replacements?

--

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 3

System OK