ASC

DTC C1608 Implausible diagnosis data








CAUTION
^ If there is any problem in the CAN bus lines, an incorrect DTC may be set. Prior to this diagnosis, diagnose the CAN bus lines.
^ 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.

OPERATION
The ASC-ECU stores DTCs and failure information in the EEPROM*.

NOTE: *:EEPROM (Electrical Erasable and Programmable ROM)

DTC SET CONDITIONS
^ This DTC is set when the failure information stored in the EEPROM is not reliable. The failure information stored in the past is not output, and only this DTC is set.
^ This DTC may occur when ASC-ECU power supply shutdown or drop between ASC-ECU is writing a data to the EEPROM.

PROBABLE CAUSES
^ Disconnection of the ASC-ECU connector or the battery terminal when the ignition switch is ON
^ Loose battery terminal
^ Abnormality in battery
^ Damaged wiring harness and connectors
^ ASC-ECU malfunction

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. M.U.T.-III CAN bus diagnosis
Use scan tool to diagnose the CAN bus lines.

Q: Is the check result normal?
YES: Go to Step 3.
NO: Repair the CAN bus lines. On completion, go to Step 2.

STEP 2. DTC recheck after resetting CAN bus lines

Q: Is DTC C1608 set?
YES: Go to Step 3.
NO: The procedure is complete.

STEP 3. Battery check

Q: Is the battery in good condition?
YES: Go to Step 5.
NO: Go to Step 4.

STEP 4. Charging system check

Q: Is the charging system in good condition?
YES: Replace the battery. Then go to Step 9.
NO: Repair or replace the charging system component(s).

STEP 5. Voltage measurement at the A-51 ASC-ECU connector





1) Disconnect the ASC-ECU connector, connect special tool ASC check harness (MB991997) to the harness-side connector, and then measure the voltage at the special tool connector side.

NOTE: Do not connect the special tool ASC check harness (MB991997) to ASC-ECU.

2) Turn the ignition switch to the ON position.
3) Measure the voltage between the terminal No.32 and the body ground.
OK: Battery positive voltage

Q: Is the check result normal?
YES: Go to Step 7.
NO: Go to Step 6.

STEP 6. Connector check: A-51 ASC-ECU connector

Q: Is the check result normal?
YES: The open or short circuit may be present in the power supply circuit. Repair the wiring harness between the A-51 ASC-ECU connector terminal No.32 and the fusible link No.27.
NO: Repair the defective connector.

STEP 7. Resistance measurement at A-51 ASC-ECU connector





1) Disconnect the ASC-ECU connector, connect special tool ASC check harness (MB991997) to the harness-side connector, and then measure the resistance at the special tool connector side.

NOTE: Do not connect the special tool ASC check harness (MB991997) to ASC-ECU.

2) Resistance between the terminal No.16 and the body ground, and between the terminal No.47 and the body ground.
OK: Continuity exists (2 Ohms or less)

Q: Is the check result normal?
YES: Go to Step 9.
NO: Go to Step 8.

STEP 8. Connector check: A-51 ASC-ECU connector

Q: Is the check result normal?
YES: An open circuit may be present in the ground circuit. Repair the wiring harness between the A-51 ASC-ECU connector terminal No.16 and the body ground, and between the A-51 ASC-ECU connector terminal No.47 and the body ground.
NO: Repair the defective connector.

STEP 9. Check whether the DTC is reset.
1) Erase the DTC.
2) Turn the ignition switch to the "LOCK" (OFF) position.
3) Turn the ignition switch to the "ON" position.

Q: Is any DTC set?
YES (DTC C1608 is set): Replace the hydraulic unit (ASC-ECU).
YES (DTC other than C1608 is set): Carry out the applicable troubleshooting for the DTC.
NO: The procedure is complete.