DTC C1264: Rear Abs Motor Circuit Open

1. Perform diagnostic system check. See DIAGNOSTIC SYSTEM CHECK. After performing diagnostic system check, go to next step.
2. If DTC C1264 occurs intermittently, go to step 13)  . If DTC C1264 does not occur intermittently, go to next step.
3. Turn ignition off. Disconnect ABS motor pack connector. Using DVOM, measure resistance between rear motor high circuit and rear motor low circuit of motor pack connector (component side). If resistance is 0.2-1.5 ohms, go to next step. If resistance is not 0.2-1.5 ohms, go to step 8)  .
4. Disconnect EBCM/EBTCM connector. See EBCM/EBTCM LOCATION  under REMOVAL & INSTALLATION. Using DVOM, measure resistance of rear motor high circuit between motor pack connector (harness side) and EBCM/EBTCM connector. If resistance is 0-2 ohms, go to next step. If resistance is not 0-2 ohms, go to step 9)  .
5. Using DVOM, measure resistance of rear motor low circuit between motor pack connector (harness side) and EBCM/EBTCM connector. If resistance is 0-2 ohms, go to next step. If resistance is not 0-2 ohms, go to step 10)  .
6. Check ABS motor pack connector and EBCM/EBTCM connector for poor terminal contact, corrosion or damage. If connectors are faulty, go to step 11)  . If connectors are okay, go to next step.
7. Reconnect ABS modulator/motor pack assembly connector. Reconnect EBCM/EBTCM connector. Test drive vehicle, obtaining speed of at least 10 MPH. Turn ignition off. Repeat drive sequence 2 more times. Using scan tool, display DTCs. If DTC C1264 sets as current in last 3 drive cycles, go to step 12)  . If DTC C1264 does not set as current in last 3 drive cycles, go to step 13)  .
8. Replace motor pack.
9. Repair open or high resistance in rear motor high circuit between motor pack and EBCM/EBTCM.
10. Repair open or high resistance in rear motor low circuit between motor pack and EBCM/EBTCM.
11. Replace all faulty terminals or connectors.
12. Replace EBCM/EBTCM. See ELECTRONIC BRAKE CONTROL MODULE/ ELECTRONIC BRAKE & TRACTION CONTROL MODULE (EBCM/EBTCM)  under REMOVAL & INSTALLATION.
13. Malfunction is not currently present. Using scan tool, select MANUAL CONTROL. While applying light pressure on brake pedal, move ABS motor of affected channel in both directions. If erratic or jumpy brake pedal movement is detected while applying and releasing ABS motor, malfunction may be intermittent.

An intermittent may be caused by a poor connection, rubbed through wire insulation, or a broken wire inside insulation. If malfunction is not current, wiggle wires of affected channel and check if DTC resets. This will assist in locating an intermittent in motor circuitry or connections. Frequency of malfunction can be determined by using enhanced diagnostic function of scan tool.

Check for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wiring connections, or damaged wiring harness. After diagnosis is complete, clear DTCs and test drive vehicle for 3 drive cycles to verify DTC does not reset. Drive cycle consists of starting vehicle, driving vehicle faster than 10 MPH, stopping vehicle, and then turning ignition off.