DTC C1254 Rear ABS Channel in Release Too Long. Opel Sintra 1999

For 1990-2009 cars
ABS Components
Antilock Brake System Schematics

### Circuit Description

DTC C1254 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 ABS brake motor wires cross.

### Conditions for Setting the DTC

DTC C1254 can only set during an ABS stop. A malfunction exists if the following conditions occur:

• | The EBCM/EBTCM commands the rear channel in release for greater than three seconds.

• | A difference of greater than 11 km/h (7 mph) exists between the vehicle reference speed and the maximum rear axle wheel speed.

• | A difference of less than 11 km/h (7 mph) exists between the vehicle reference speed and the maximum rear axle wheel speed.

### 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. Use the Scan Tool hydraulic test in order 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 OFF position.
2. Raise and suitably support the rear of the vehicle.
3. Verify that the rear wheels are approximately 15 cm (6 in) above the floor.
4. Spin each of the rear wheels by hand.

Is it possible to spin each rear wheel freely by hand?

--

Go to Step 5

Go to Step 11

5

1. Turn the ignition switch to the RUN position, engine off.
2. Select the Manual Control function on the scan tool.
3. Select the rear axle ABS Motor Apply function on the scan tool.
4. Apply firm pressure to the brake pedal.
5. Use the scan tool in order to apply the rear axle ABS motor.
6. Spin each rear wheel by hand.

Is it possible to freely spin each rear wheel?

--

Go to Step 6

Go to Step 12

6

1. Continue to apply firm pressure to the brake pedal.
2. Use the scan tool in order to command a Motor Release of the rear axle ABS motor.

Did the brake pedal fall?

--

Go to Step 7

Go to Step 9

7

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 brake motor pack from the ABS brake modulator. Refer to ABS Motor Pack Replacement .
4. Reconnect 6-way motor pack connector to motor pack.
5. Turn the ignition switch to the RUN position, engine off.
6. Use the scan tool in order to perform a ABS brake motor pack motor test.

Do all three of the ABS brake motor pack gears (small gears) spin freely?

--

Go to Step 8

Go to Step 10

8 | Replace the ABS brake modulator. Refer to Brake Modulator Replacement . Is the repair complete? | -- | Go to Diagnostic System Check - ABS | --
9 | Repair the crossed wires to the rear ABS motor (CKT 1284 and CKT 1285). Is the repair complete? | -- | Go to Diagnostic System Check - ABS | --
10 | Replace the ABS brake motor pack. Refer to ABS Motor Pack Replacement . Is the repair complete? | -- | Go to Diagnostic System Check - ABS | --
11 | Repair the source of resistance in the base brake system. Refer to Diagnosis and Inspection in Brakes. Is the repair complete? | -- | Go to Diagnostic System Check - ABS | --
12 | 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