DTC C1254 Rear ABS Channel in Release Too Long. Buick Century 1998

For 1990-2009 cars only

Makes 🢒 Buick 🢒 1998 🢒 Century 🢒 Brakes 🢒 Antilock Brake System 🢒 DTC C1254 Rear ABS Channel in Release Too Long

ABS Components
Antilock Brake System Schematics
Handling ESD Sensitive Parts Notice

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 kmh (7 mph) exists between the vehicle reference speed and the maximum rear axle wheel speed.

A malfunction exists if the following conditions occur:

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

•	A difference of less than 11 kmh (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/ETS/TCS disables.

•	The amber ABS/ETS/TCS warning indicator(s) turn 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.

•	100 drive cycles pass with no DTC(s) detected.

Diagnostic Aids

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

•

Sticking

•

Binding

Use the enhanced diagnostic function of the Scan Tool in order to measure the frequency of the malfunction. Refer to the Scan Tool manual 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:

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

Important: Zero the J 39200 test leads before making any resistance measurements. Refer to the J 39200 user's manual.

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

•	Excessive drag

•	High resistance

Step

Action

Value(s)

Yes

Was the Diagnostic System Check performed?

Go to Step 2

Go to Diagnostic System Check

Turn the ignition switch to the RUN position.

Do not start the engine.

Install a Scan Tool .
Use the Scan Tool in order to read the DTCs.

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

Go to the appropriate DTC table.

Go to Step 3

Select Data List on the Scan Tool .
Drive the vehicle, slowly decelerating from 56 km/h to 0 km/h (35 mph to 0 mph).
Monitor all of the wheel speed sensor speeds while driving.

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

Go to one of the following:

•	DTC C1225 LF Excessive Wheel Speed Variation

•	DTC C1226 RF Excessive Wheel Speed Variation

•	DTC C1227 LR Excessive Wheel Speed Variation

•	DTC C1228 RR Excessive Wheel Speed Variation

Go to Step 4

Turn the ignition switch to the OFF position.
Raise and suitably support the rear of the vehicle. Make sure that the two rear wheels are off of the ground.

Refer to Lifting and Jacking the Vehicle in General Information.

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

Turn the ignition switch to the RUN position.

Do not start the engine.

Select the Manual Control function on the Scan Tool .
Select the rear axle ABS Motor Apply function on the Scan Tool .
Apply firm pressure to the brake pedal.
Use the Scan Tool in order to apply the rear axle ABS motor.
Spin each rear wheel by hand.

Is it possible to freely spin each rear wheel?

Go to Step 6

Go to Step 12

Continue to apply firm pressure to the brake pedal.
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

Use the Scan Tool in order to perform the Gear Tension Relief function.
Turn the ignition switch to the OFF position.
Separate the ABS brake motor pack from the ABS brake modulator, if it is disconnected.
Turn the ignition switch to the RUN position.

Do not start the engine.