C1226
DTC C1226/C1231/C1236/C1241/C1246/C1251/C1256/C1261: ABS Solenoid ValveSolenoid Valve and Motor Power Supply Circuit:
CAUTION: If there is any problem in the CAN bus lines, an incorrect diagnostic trouble code may be set. Prior to this diagnosis, diagnose the CAN bus lines.
CIRCUIT OPERATION
^ The ABS-ECU contains the power supply circuit (terminal 1) for the solenoid valve. The solenoid valve is energized by the valve relay, which is integrated in the ABS-ECU.
^ The valve relay, which is integrated in the ABS-ECU, is always energizing the solenoid valve unless the initial check is in progress when the ignition switch is turned on.
^ The ABS-ECU activates the solenoid valve by turning on its driving transistor.
ABS DTC SET CONDITIONS
These diagnostic trouble codes will be set under the cases below.
^ The solenoid valve is not energized even after the ABS-ECU has turned on the driving transistor (Open circuit is present in the power supply circuit to the ABS-ECU solenoid valve, or the valve relay has failed).
^ The solenoid valve is not energized even after the ABS-ECU has turned on the driving transistor (Open circuit is present in the solenoid valve circuit inside the ABS-ECU, or the valve relay has failed).
^ After the ABS-ECU has turned off the driving transistor, the solenoid valve still remains energized (short in the solenoid valve circuit).
^ When a solenoid valve failure is detected
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 1) to the ABS-ECU solenoid valve or ground circuit (terminal 2). For diagnosis procedures, refer to "How to cope with past trouble". Initial Inspection and Diagnostic Overview
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) Erase the DTC.
(2) Turn the ignition switch to the "ON" position.
(3) Check if the DTC is set.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is DTC C1226, C1231, C1236, C1241, C1246, C1251, C1256 or C1261 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) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal 1 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). 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 1 and fusible link No. 3.Then go to Step 8.
STEP 5. Measure the resistance at ABS-ECU connector A02.
(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 2 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). 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 2 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 C1226, C1231, C1236, C1241, C1246, C1251, C1256 or C1261 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.
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 C1226, C1231, C1236, C1241, C1246, C1251, C1256 or C1261 set?
YES: Go to Step 1.
NO: The procedure is complete.