DTC C1608: Implausible Diagnosis Data

DTC C1608: Implausible diagnosis data

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.
^ Whenever the ECU is replaced, ensure that the CAN bus lines are normal.
^ When the hydraulic unit (integrated with ASC-ECU) is replaced, after turning the ignition switch ON and OFF (vehicle information from ETACS-ECU is registered), always perform the calibration of steering wheel sensor, G and yaw rate sensor, brake fluid pressure sensor, cut valve, and inlet valve.
^ When the ASC-ECU connector or battery terminal is disconnected with the ignition switch ON, this diagnostic trouble code may be set.
^ When this diagnostic trouble code is set, no other failure information will be set.

CIRCUIT OPERATION
The ASC-ECU stores diagnostic trouble codes and failure information in the EEPROM*.

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

DTC SET CONDITIONS
This diagnostic trouble code is set under the cases below.
^ Trouble information stored in the EEPROM is not reliable.
^ ASC-ECU power supply is shut down while the trouble information is being written to 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
^ MB991997: ASC check harness

STEP 1. Using scan tool MB991958, diagnose the CAN bus lines.
Using scan tool MB991958, diagnose the CAN bus lines.

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

STEP 2. DTC recheck after repairing the CAN bus line

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

STEP 3. Battery check

Q: Is the battery in good condition?
YES: Go to Step 4.
NO: Repair or replace the charging system component(s), and then go to Step 17.

STEP 4. Charging system check

Q: Is the charging system in good condition?
YES: Go to Step 5.
NO: Repair or replace the charging system component(s), and then go to Step 17.

STEP 5. Voltage measurement at A-05 ASC-ECU connector

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

NOTE: Do not connect the special tool to ASC-ECU.

2) Measure the voltage between the terminal No.2 and the body ground.
OK: System voltage

Q: Is the check result normal?
YES: Go to Step 15.
NO: Go to Step 9.

STEP 9. Connector check: C-309 ETACS-ECU connector

Q: Is the check result normal?
YES: Go to Step 10.
NO: Repair the defective connector.

STEP 10. Voltage measurement at the C-309 ETACS-ECU connector
1) Disconnect the connector, and measure at the wiring harness-side connector.
2) Measure the voltage between the terminal No.1 and the body ground.
OK: System voltage

Q: Is the check result normal?
YES: Go to Step 11.
NO: Repair the wiring harness between C-309 ETACS-ECU connector terminal No. 1 and the fusible link No. 34.

STEP 11. Connector check: C-315 ETACS-ECU connector

Q: Is the check result normal?
YES: Go to Step 12.
NO: Repair the defective connector.

STEP 12. Voltage measurement at the C-315 ETACS-ECU connector
1) Without disconnecting the connector, measure by backprobing.
2) Measure the voltage between the terminal No.4 and the body ground.
OK: System voltage

Q: Is the check result normal?
YES: Go to Step 14.
NO: Go to Step 13.

STEP 13. Connector check: C-103 joint connector, C-130 intermediate connector

Q: Is the check result normal?
YES: Go to Step 14.
NO: Repair the defective connector.

STEP 14. Wiring harness check between A-05 ASC-ECU connector terminal No. 2 and C-315 ETACS-ECU connector terminal No. 4
^ Open or short circuit check

Q: Is the check result normal?
YES: Go to Step 15.
NO: Repair the wiring harness.

STEP 15. Resistance measurement at A-05 ASC-ECU connector

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

NOTE: Do not connect the special tool 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 C2 or less)

Q: Is the check result normal?
YES: Go to Step 17.
NO: Go to Step 16.

STEP 16. Connector check: A-05 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 A-05 ASC-ECU connector terminal No. 16 and the body ground as well as between A-05 ASC-ECU connector terminal No. 47 and the body ground.
NO: Repair the defective connector, then go to Step 17.

STEP 17. Check whether the DTC is reset.
1) Erase the diagnostic trouble code.
2) Turn the ignition switch to the "LOCK" (OFF) position.
3) Turn the ignition switch to the "ON" position.

Q: Is the DTC C1608 set?
YES: Replace the hydraulic unit (incorporates in ASC-ECU). Then go to Step 18.
NO: Go to Step 19.

STEP 18. Check whether the DTC is reset.

Q: Is the DTC C1608 set?
YES: Return to Step 1.
NO: Go to Step 19.

STEP 19. Check for diagnostic trouble codes of other systems
Perform a test run of the vehicle at the vehicle speed of 12 mph (20 km/h) or more. Then, check if any other diagnostic trouble code is set in ASC-ECU.

Q: Is any DTC set?
YES: Perform troubleshooting for the diagnostic trouble code that is set.
NO: This diagnosis is complete.