C1246

DTC C1246: Rear ABS Channel Will Not Move (Part 1 Of 2):

DTC C1246: Rear ABS Channel Will Not Move (Part 2 Of 2):

DTC C1246 Schematic:

Circuit Description
This DTC is designed to detect bound-up ESB's, stuck motor or a seized hydraulic modulator. Release is commanded during initialization. The ESB should release the motor, resulting in feedback current being less than commanded current (motor is spinning freely). If the motor is not moving, feedback current will be equal to commanded current.

Conditions for Setting the DTC
This DTC will set when the following conditions are met:
^ This DTC can be set during an ABS event.
^ This DTC can be set during Tech 2 scan tool testing. The Electronic Brake Control Module (EBCM) commands the left front motor in the reverse and forward direction to ensure the motor moves properly.
^ The EBCM detects a condition in which it cannot move the left motor in either direction (sense current of the left motor is greater than 8A). If the motor pack was removed from the hydraulic modulator without performing the Tech 2 scan tool's Gear Tension Relief function, this DTC may set after motor pack-to-hydraulic modulator reassembly.

Action Taken When the DTC Sets
This malfunction indicates the left front channel cannot be moved properly. A malfunction DTC is stored, ABS is disabled and both the amber ABS indicator lamp and the red BRAKE warning lamp are turned ON.

Conditions for Clearing the DTC
^ Conditions for the malfunction are no longer present and the Tech 2 scan tool Clear DTC Information function is used.
^ One hundred drive cycles have passed with no malfunctions detected.

Diagnostic Aids
The following list contains items that need to be inspected when diagnosing this system:
^ Faulty motor pack (ESB does not release motor).
^ Faulty hydraulic modulator (piston sticking or at the bottom of the bore, or shaft binding).
An intermittent malfunction in this DTC may result from a mechanical part of the system that sticks or binds.
The frequency of the malfunction can be checked by using the Enhanced Diagnostic function of the Tech 2 scan tool, as described in Enhanced Diagnostics.



Test Description
The numbers below refer to step numbers on the diagnostic table.
2. Checks for possible open or shorted rear motor circuit(s).
3. Checks rear motor for movement.
4. Checks rear motor for movement.
5. Checks whether the hydraulic modulator rear channel is stuck or motor pack is faulty.
6. Checks if this DTC resets after two drive cycles.