C1246

CIRCUIT DESCRIPTION
Diagnostic Trouble Code (DTC) C1246 detects a bound-up ESB, a stuck ABS motor, or a seized brake modulator. When the release is commanded during initialization, the ESB 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
Diagnostic Trouble Code (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 EBCM detects a condition in which the EBCM cannot move the ABS motor in either direction.
If the motor pack was removed from the hydraulic modulator without performing the scan tool's Gear Tension Relief function, this DTC may set after motor pack-to-hydraulic modulator reassembly.

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 Diagnostic Trouble Code (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.
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.

TEST DESCRIPTION
2. This test ensures that the motor circuits are in the proper connector cavity.
3. This test checks the ability of the motor to move by releasing hydraulic pressure to the wheel cylinders.
4. This test checks the ability of the motor to move by applying hydraulic pressure to the wheel cylinders.
5. This test checks for motor movement by comparing the feedback current to the command current during apply.
6. This test checks for a short between the motor high and the motor low circuits.
7. This test checks for a shorted motor.
9. This test determines if the malfunction is caused by the Electronic Brake Control Module (EBCM).
10. This test determines if the hydraulic modulator is functioning properly by manually moving the piston.

Part 1 Of 3:

Part 2 Of 3:

Part 3 Of 3:

DTC C1246 REAR ABS CHANNEL DOES NOT MOVE