C1266
DTC C1266: Motor system (seizure)DTC C1273: Motor relay problem (stays off)
DTC C1274: Motor relay problem (stays on)
CAUTION:
^ there is any problem in the CAN bus lines, an incorrect diagnostic trouble code may be set. Diagnose the CAN bus lines before the DTC.
^ Whenever the ECU is replaced, ensure that the CAN bus lines are normal.
CIRCUIT OPERATION
^ The ABS-ECU contains the power supply circuit (terminal 19) for the pump motor. The pump motor is energized by the motor relay, which is integrated in the ABS-ECU.
^ The motor relay, which is integrated in the ABS-ECU, is always off unless the motor solenoid valve check is activated when the vehicle is started.
^ The ABS-ECU activates the pump motor by turning on the ECU built in motor relay when the ABS is working.
DTC SET CONDITIONS
These diagnostic trouble codes will be set under the cases below.
DTC C1266: Motor system (seizure)
^ This DTC is set when the ECU determines the pump motor is not running smoothly (i.e. motor seizure) by the motor relay ON/OFF.
DTC C1273: Motor relay problem (stays off)
^ If the ABS-ECU determines that the motor is not running after the motor relay is turned on, the ECU determines that the motor relay is stuck off, and sets this DTC.
DTC C1274: Motor relay problem (stays on)
^ If the ABS-ECU determines that the motor is running after the motor relay is turned off, the ECU determines that the motor relay is stuck on, and sets this DTC.
TROUBLESHOOTING HINTS (THE MOST LIKELY CAUSES FOR THESE DTCS ARE TO SET ARE:)
Current trouble
^ Damaged wiring harness or connector
^ Malfunction of the hydraulic unit (integrated with ABS-ECU)
PAST TROUBLE
^ Carry out diagnosis with particular emphasis on connector(s) or wiring harness between the power supply circuit (terminal 19) to the ABS-ECU motor or ground circuit (terminal 18). For diagnosis procedures, refer to "How to cope with past trouble".
DIAGNOSIS
Required Special Tools:
^ MB991958: Scan Tool (M.U.T.-III Sub Assembly)
^ MB991824: Vehicle Communication Interface (V.C.I.)
^ MB991827: M.U.T.-III USB Cable
^ MB991910: M.U.T.-III Main Harness A
^ MB991970: ABS Check Harness
STEP 1. Using scan tool MB991958, diagnose the CAN bus line.
CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
1) Connect scan tool MB991958 to the data link connector.
2) Turn the ignition switch to the "ON" position.
3) Diagnose the CAN bus line.
4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the CAN bus line found to be normal?
YES: Go to Step 3.
NO: Repair the CAN bus line. Then go to Step 2.
STEP 2. Recheck for diagnostic trouble code.
CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
1) Turn the ignition switch to the "ON" position.
2) Erase the DTC.
3) Turn the ignition switch to the "LOCK" (OFF) position.
4) Turn the ignition switch to the "ON" position.
5) Check if the DTC is set.
6) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is DTC C1266, C1273 or C1274 set?
YES: Go to Step 3.
NO: The procedure is complete.
STEP 3. Measure the voltage at ABS-ECU connector A-02.
1) Disconnect the connector A-02, and connect special tool ABS Check Harness (MB991970) to the wiring harness-side connector.
NOTE: Do not connect special tool ABS Check Harness (MB991970) to the ABS-ECU.
2) Measure the voltage between terminal 19 and ground. It should be approximately 12 volts (battery positive voltage).
Q: Is the voltage approximately 12 volts (battery positive voltage)?
YES: Go to Step 5.
NO: Go to Step 4.
STEP 4. Check ABS-ECU connector A-02 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q: Is ABS-ECU connector A-02 damaged?
YES: Repair or replace the damaged component(s). Refer to Harness Connector Inspection. Then go to Step 8.
NO: An open or short circuit may be present in the solenoid valve power supply circuit. Repair the wiring harness between ABS-ECU connector A-02 terminal 19 and fusible link No.3. Then go to Step 8.
STEP 5. Measure the resistance at ABS-ECU connector A-02.
1) Disconnect the connector A-02, and connect special tool ABS Check Harness (MB991970) to the wiring harness-side connector.
NOTE: Do not connect special tool ABS Check Harness (MB991970) to the ABS-ECU.
2) Measure the resistance between terminal 18 and ground. It should be 2 ohms or less.
Q: Is the measured resistance 2 ohms or less?
YES: Go to Step 7.
NO: Go to Step 6.
STEP 6. Check ABS-ECU connector A-02 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q: Is ABS-ECU connector A-02 damaged?
YES: Repair or replace the damaged component(s). Refer to Harness Connector Inspection. Then go to Step 8.
NO: An open circuit may be present in the ground circuit. Repair the wiring harness between ABS-ECU connector A-02 terminal 18 and the body ground. Then go to Step 8.
STEP 7. Recheck for diagnostic trouble code. Check again if the DTC is set.
1) Turn the ignition switch to the "ON" position.
2) Erase the DTC
3) Turn the ignition switch to the "LOCK" (OFF) position.
4) Turn the ignition switch to the "ON" position.
5) Check if the DTC is set.
6) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is DTC C1266, C1273 or C1274 set?
YES: Replace the hydraulic unit (integrated with ABS-ECU). Then go to Step 8.
NO: It can be assumed that this malfunction is intermittent. Refer to How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction.
STEP 8. Recheck for diagnostic trouble code. Check again if the DTC is set.
1) Turn the ignition switch to the "ON" position.
2) Erase the DTC.
3) Turn the ignition switch to the "LOCK" (OFF) position.
4) Turn the ignition switch to the "ON" position.
5) Check if the DTC is set.
6) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is DTC C1266, C1273 or C1274 set?
YES: Go to Step 1.
NO: The procedure is complete.