C1246

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CIRCUIT DESCRIPTION
DTC C1246 detects a bound-up ESB, a stuck ABS motor, or a seized brake modulator. When the release is commanded during initialization, the Expansion Spring Brake (ESB) should release the ABS motor, resulting in the sensed current being less than the commanded current (motor spins freely). If the ABS motor is not moving, sensed current will be equal to stall currents.

CONDITIONS FOR SETTING THE DTC
DTC C1246 can set during brake motor initialization at the following speeds:
^ 0 km (0 mph) when the brake is off
^ 5 km (3 mph) when the brake is on

DTC C1246 can set during ABS stops. A malfunction exists if the EBCM/EBTCM detects a condition in which the EBCM/EBTCM cannot move the ABS motor in either direction.

ACTION TAKEN WHEN THE DTC SETS
^ A malfunction Diagnostic Trouble Code (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. 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.

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