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DTC C2104: Faulty valve power supply circuit
 
 
 
 
caution
  • If there is any problem in the CAN bus lines, an incorrect diagnostic trouble code may be stored. Prior to this diagnosis, diagnose the CAN bus lines (Refer to GROUP 54C - CAN Bus Line Diagnostic Flow ).
  • Whenever ECU is replaced, ensure that the CAN bus lines are normal.
  • When the hydraulic unit (integrated with ASC-ECU) is replaced, always carry out the calibration of the steering wheel sensor, the G and yaw rate sensor and brake fluid pressure sensor (Refer to , and ).
 
 
OPERATION
  • ASC-ECU contains the power supply circuit (terminal No. 32) for the solenoid valve. The solenoid valve is energized by the valve relay, which is incorporated in ASC-ECU.
  • The valve relay, which is incorporated in ASC-ECU, is always energizing the solenoid valve unless the initial check is in progress when the ignition switch is turned on, or the recurrent system check is in progress.
 
 
 
DTC SET CONDITIONS
This diagnostic trouble codes will be stored when the solenoid valve supply voltage is not within the standard value.
 
 
 
PROBABLE CAUSES
Current trouble
  • Fusible link malfunction
  • Damaged wiring harness and connectors
  • Abnormality in battery or generator
  • ASC-ECU malfunction
Past trouble
  • Carry out diagnosis with particular emphasis on wiring harness and connector failures between the power supply circuit (terminal No.25) to ASC-ECU solenoid valve or ground circuit (terminals No.13 and 38). For diagnosis procedures, refer to How to treat past trouble (Refer to GROUP 00 - How to Use Troubleshooting/How to Treat Past Trouble ).
 
 
 
 
DIAGNOSIS
STEP 1. Using scan tool MB991958, diagnose the CAN bus lines.
Use scan tool to diagnose the CAN bus lines.
Is the check result normal?
Go to Step 3.
Repair the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ). On completion, go to Step 2.
 
STEP 2. DTC recheck after resetting CAN bus lines
Is DTC C2104 stored?
Go to Step 3.
The procedure is complete.
 
STEP 3. Battery check
Refer to GROUP 54A - Battery Test .
Is the battery in good condition?
Go to Step 5.
Replace the battery. Then go to Step 4.
 
STEP 4. Charging system check
Refer to GROUP 16 - On-vehicle Service/Output Current Test .
Is the charging system in good condition?
Go to Step 5.
Repair or replace the charging system component(s). Then go to Step 11.
 
STEP 5. Connector check: A-03 ASC-ECU connector
Is the check result normal?
Go to Step 6.
Repair the defective connector. Then go to Step 11.
 
STEP 6. Fusible link check: Check the fusible link No.27.
Visually check for open circuit in the fusible link No.27.
Is the check result normal?
Go to Step 8.
Go to Step 7.
 
STEP 7. Resistance measurement at A-03 ASC-ECU connector
(1) Disconnect the ASC-ECU connector, connect special tool test harness (MB991709) to the harness-side connector, and then measure the resistance at the special tool connector side.
noteDo not connect the special tool test harness (MB991709) to ASC-ECU.
(2) Disconnect the fusible link No.27.
(3) Measure the resistance between the terminal No.25 and the body ground.
OK: No continuity
Is the check result normal?
Replace the fusible link No.27. Then go to Step 11.
The short circuit may be present in the power supply circuit. Repair the wiring harness between the A-03 ASC-ECU connector terminal No.25 and the fusible link No.27, and then replace the fusible link No.27. Then go to Step 11.
 
STEP 8. Voltage measurement at the A-03 ASC-ECU connector
(1) Disconnect the ASC-ECU connector, connect special tool test harness (MB991709) to the harness-side connector, and then measure the voltage at the special tool connector side.
noteDo not connect the special tool test harness (MB991709) to ASC-ECU.
(2) Measure the voltage between the terminal No.25 and the body ground.
OK: Approximately system voltage
Is the check result normal?
Go to Step 9.
The open circuit may be present in the power supply circuit. Repair the wiring harness between the A-03 ASC-ECU connector terminal No.25 and the fusible link No.27. Then go to Step 11.
 
STEP 9. Resistance measurement at A-03 ASC-ECU connector
(1) Disconnect the ASC-ECU connector, connect special tool test harness (MB991709) to the harness-side connector, and then measure the resistance at the special tool connector side.
noteDo not connect the special tool test harness (MB991709) to ASC-ECU.
(2) Measure the resistance between the terminal No.13 and the body ground, and between the terminal No.38 and the body ground.
OK: Continuity exists (2 Ω or less)
Is the check result normal?
Go to Step 10.
An open circuit may be present in the ground circuit. Repair the wiring harness between the A-03 ASC-ECU connector terminal No.13 and the body ground, and between the A-03 ASC-ECU connector terminal No.38 and the body ground. Then go to Step 11.
 
STEP 10. Check whether the DTC is stored again.
Erase the DTC.
Is DTC C2104 stored?
Replace the hydraulic unit (integrated with ASC-ECU) (Refer to ). Then go to Step 11.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/How to Cope with Intermittent Malfunctions ).
 
STEP 11. Check whether the DTC is stored again.
Erase the DTC.
Is DTC C2104 stored?
Return to Step 1.
The procedure is complete.