C1276

DTC C1276: Valve 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.

CAUTION:
Whenever the ECU is replaced, ensure that the CAN bus lines are normal.

CAUTION:
When I replace hydraulic unit (integrated with TCL/ASC-ECU), Always perform the calibration of steering wheel sensor and yaw rate sensor.

CIRCUIT OPERATION

- The TCL/ASC-ECU contains the power supply circuit (terminal 32) for the solenoid valve. The solenoid valve is energized by the valve relay, which is incorporated in the TCL/ASC-ECU.
- The valve relay, which is incorporated in the TCL/ASC-ECU, is always energizing the solenoid valve unless the initial check is in progress when the ignition switch is turned on.

TCL/ASC DTC SET CONDITIONS

- When the solenoid valve power supply voltage is off the normal range, this DTC is output.

TROUBLESHOOTING HINTS (THE MOST LIKELY CAUSES FOR THESE DTCS ARE TO SET ARE:)

Current trouble

- Defective battery
- Charging system failed
- Damaged wiring harness or connector

- Malfunction of the hydraulic unit (integrated with TCL/ASC-ECU)

PAST TROUBLE

Carry out diagnosis with particular emphasis on connector(s) or wiring harness in the power supply circuit (terminal 32) to the TCL/ASC-ECU solenoid valve or ground circuit (terminal 16, 47). For diagnosis procedures, refer to "How to cope with past trouble" How to Treat 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
- MB991997: ASC 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 2.

NO Repair the CAN bus line CAN Bus Diagnostics Chart).
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 C1276 set?

YES Go to Step 3.

NO The procedure is complete.

STEP 3. Battery check

Battery Test.

Q. Is the battery in good condition?

YES Go to Step 5.
NO Replace the battery. Then go to Step 4.
STEP 4. Charging system check

Initial Inspection and Diagnostic Overview.

Q. Is the charging system in good condition?

YES Go to Step 5.
NO Repair or replace the charging system component(s). Then go to Step 10.
STEP 5. Measure the voltage at TCL/ASC-ECU connector A-38.

(1)Disconnect the connector A-38, and connect special tool MB991997 to the wiring harness-side connector.
NOTE:
Do not connect special tool MB991997 to the TCL/ASC-ECU.

(2)Turn the ignition switch to the "ON" position.
(3)Measure the voltage between terminal 32 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 7.

NO Go to Step 6.

STEP 6. Check TCL/ASC-ECU connector A-38 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q. Is TCL/ASC-ECU connector A-38 damaged?

YES Repair or replace the damaged component(s). Harness Connector Inspection. Then go to Step 10.

NO An open or short circuit may be present in the solenoid valve power supply circuit.
Repair the wiring harness between TCL/ASC-ECU connector A-38 terminal 32 and fusible link No.3. Then go to Step 10.

STEP 7. Measure the resistance at TCL/ASC-ECU connector A-38.

(1)Disconnect the connector A-38, and connect special tool MB991997 to the wiring harness-side connector.
NOTE:
Do not connect special tool MB991997 to the TCL/ASC-ECU.

(2)Measure the resistance between terminal 16, 47 and ground. It should be 2 ohms or less.

Q. Is the measured resistance 2 ohms or less?

YES Go to Step 9.

NO Go to Step 8.

STEP 8. Check TCL/ASC-ECU connector A-38 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q. Is TCL/ASC-ECU connector A-38 damaged?

YES Repair or replace the damaged component(s). Harness Connector Inspection. Then go to Step 10.

NO An open circuit may be present in the ground circuit. Repair the wiring harness between TCL/ASC-ECU connector A-38 terminal 16, 47 and the body ground. Then go to Step 10 .

STEP 9. 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 C1276 set?

YES Replace the hydraulic unit (integrated with TCL/ASC-ECU). Then go to Step 10.

NO It can be assumed that this malfunction is intermittent. How to Cope With Intermittent Malfunctions.

STEP 10. Recheck for diagnostic trouble code.