C1246

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Circuit Description
Diagnostic Trouble Code (DTC) C1246 detects a bound-up EBS, a stuck Antilock Brake System (ABS) motor, or a seized brake modulator. When the release is commanded during initialization, the Expansion Spring Brake (EBS) should release the ABS motor, resulting in the feedback current being less than the commanded current (motor spins freely). If the ABS motor is not moving, feedback current will be equal to commanded current.

Conditions for Setting the DTC
DTC C1246 can set during brake motor initialization at the following speeds:
- 0 km/h (0 mph) when the brake is off
- 5 km/h (3 mph) when the brake is on
DTC C1246 can set during ABS stops
A malfunction exists if the Electronic Brake Control Module (EBCM) detects a condition in which the EBCM cannot move the ABS motor in either direction.

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.
- 100 drive cycles pass with no DTCs detected. A drive cycle consists of starting the vehicle, driving the vehicle over 16 km/h (10 mph), stopping and then turning the ignition off.

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. DTC C1246 may set after modulator disassembly if the modulator pistons are positioned at the bottom of the modulator piston bore. Depending on the frequency of the malfunction, a physical inspection of the mechanical parts suspected of causing the malfunction may be necessary.
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/in (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. Refer to the J 39200 user's manual.