Anti-Lock Braking System (ABS)

DTC C1276: Power Supply Circuit Failure of Valves

Solenoid 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 26) 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.

ABS DTC SET CONDITIONS
This diagnostic trouble code will be set under the cases below.
^ After the ABS-ECU turned on the valve relay, the solenoid valve is not energized (valve relay OFF failure).
^ After the ABS-ECU turned off the valve relay, the solenoid valve still remains energized (valve relay ON failure).

TROUBLESHOOTING HINTS (THE MOST LIKELY CAUSES FOR THESE DTCS ARE TO SET ARE:)
Correct 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 26) to the ABS-ECU solenoid valve or ground circuit (terminal 14). For diagnosis procedures, refer to "How to treat past trouble". Initial Inspection and Diagnostic Overview

DIAGNOSIS

Required Special Tools:
^ MB991958: Scan Tool (MUT-III Sub Assembly)
^ MB991824: V.C.I.
^ MB991827: MUT-III USB Cable
^ MB991910: MUT-III Main Harness A

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. 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: Replace the hydraulic unit (integrated with ABS-ECU).
NO: The procedure is complete.