GM Service Manual Online
For 1990-2009 cars only

Object Number: 155205  Size: SF
ABS Components
Antilock Brake System Schematics

Circuit Description

DTC C1253 diagnoses an ABS motor that energizes longer than expected. The following conditions may cause the longer period of being energized:

    • A wheel speed sensor malfunctions.
    • The ABS motor does not turn.
    • The right front brake solenoid valve mechanically fails open.
    • The ABS brake motor wires cross.

Conditions for Setting the DTC

DTC C1253 can only set during an ABS stop. A malfunction exists if the EBCM/EBTCM commands the right front ABS channel in release for greater than three seconds.

Action Taken When the DTC Sets

    • A malfunction DTC stores.
    • The ABS/TCS disables.
    • The amber ABS/TCS warning indicators turn on.

Conditions for Clearing the DTC

    • The condition responsible for setting the DTC no longer exists and the Scan Tool Clear DTC function is used.
    • 100 drive cycles pass with no DTC detected.

Diagnostic Aids

The following conditions may cause an intermittent malfunction if the conditions exist in a mechanical part of the system:

    • Sticking
    • Binding

Inspect for and correct the following conditions in the base brake or suspension system before proceeding with the DTC diagnosis:

    • Excessive drag
    • High resistance

Use the enhanced diagnostic function of the Scan Tool in order to measure the frequency of the malfunction. Refer to the Scan Tool manual or Scan Tool Diagnostics located in this section for the procedure. DTC C1253 may occur if the vehicle is on ice and the steering wheel is turned to lock during braking. Use the scan tool hydraulic test to ensure the total brake system is functional. Thoroughly inspect any circuitry that may be causing the intermittent complaint for the following conditions:

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

Clear the DTCs after completing the diagnosis. Test drive the vehicle for three drive cycles in order to verify that the DTC does not reset. Use the following procedure in order to complete one drive cycle:

  1. Start the vehicle.
  2. Drive the vehicle over 16 km/h (10 mph).
  3. Stop the vehicle.
  4. Turn the ignition to the OFF position.

Important: Zero the J 39200 test leads before making any resistance measurements.

Step

Action

Value(s)

Yes

No

1

Was the Diagnostic System Check performed?

--

Go to Step 2

Go to Diagnostic System Check - ABS

2

  1. Install a scan tool.
  2. Turn the ignition switch to the RUN position, engine off.
  3. Use the scan tool in order to read the DTCs.

Are there any wheel speed sensor DTCs that set as current DTCs?

--

Go to Diagnostic Trouble Code (DTC) List for appropriate DTC

Go to Step 3

3

  1. Select Data List on the scan tool.
  2. Drive the vehicle slowly decelerating from 56 km/h to 0 km/h (35 mph to 0 mph).
  3. Monitor all of the wheel speed sensor speeds while driving.

Do any of the wheel speed sensors indicate erratic or intermittent operation?

--

Go to Diagnostic Trouble Code (DTC) List for Excessive Wheel Speed Sensor Variation DTC

Go to Step 4

4

  1. Turn the ignition switch to the RUN position, engine off.
  2. Select Special Functions on the scan tool.
  3. Select the Manual Control function on the scan tool.
  4. Select the right front ABS Motor Apply function on the scan tool.
  5. Use the scan tool to apply the right front ABS motor.
  6. Apply firm pressure to the brake pedal.
  7. Select the right front ABS Motor Release function on the scan tool.
  8. Use the scan tool in order to release the right front ABS motor.

Does the brake pedal fall?

--

Go to Step 5

Go to Step 8

5

  1. Remove the firm pressure from the brake pedal.
  2. Select the Manual Control function on the scan tool.
  3. Select the right front ABS Brake Solenoid Valve on the scan tool.
  4. Use the scan tool in order to command the right front ABS brake solenoid valve on.
  5. Apply firm pressure to the brake pedal.

Does the brake pedal fall?

--

Go to Step 7

Go to Step 6

6

  1. Continue to apply firm pressure to the brake pedal.
  2. Use the scan tool in order to command the right front ABS brake solenoid valve off.

Did the brake pedal fall?

--

Go to Step 14

Go to Step 7

7

  1. Remove the firm pressure from the brake pedal.
  2. Turn the ignition switch to the OFF position.
  3. Remove the right front ABS brake solenoid valve.
  4. Remove the left front ABS brake solenoid valve.
  5. Reinstall the right front ABS brake solenoid valve to the left front ABS brake solenoid valve position.
  6. Reinstall the left front ABS brake solenoid valve to the right front ABS brake solenoid valve position.
  7. Turn the ignition switch to the RUN position, engine off.
  8. Select the Manual Control function on the scan tool.
  9. Select the right front ABS Brake Solenoid Valve on the scan tool.
  10. Use the scan tool in order to command the right front ABS brake solenoid valve on.
  11. Apply firm pressure to the brake pedal.

Does the brake pedal fall?

--

Go to Step 10

Go to Step 11

8

Did the brake pedal rise?

--

Go to Step 12

Go to Step 9

9

  1. Use the scan tool in order to perform the Gear Tension Relief function.
  2. Turn the ignition switch to the OFF position.
  3. Separate the ABS motor pack from the ABS brake modulator. Refer to ABS Motor Pack Replacement .
  4. Grasp the ABS brake modulator right front gear.
  5. (The ABS brake modulator right front gear is the large gear that is the closest to the rear when the ABS brake modulator is mounted in the vehicle.)

  6. Attempt to rotate the ABS brake modulator right front gear in either direction.

Is it possible to rotate the ABS brake modulator right front gear by hand?

--

Go to Step 13

Go to Step 10

10

Replace the ABS brake modulator. Refer to Brake Modulator Replacement .

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--

11

Replace the ABS brake solenoid valve that was originally in the right front ABS brake solenoid valve position. Refer to Brake Solenoid Valve Replacement .

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--

12

Repair the crossed wires to the right front ABS motor (CKT 1282 and CKT 1283).

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--

13

Replace the ABS brake motor pack. Refer to ABS Motor Pack Replacement .

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--

14

The malfunction is intermittent or not present at this time.

Is a concern still present?

--

Go to Diagnostic Aids

Go to Diagnostic System Check - ABS