Code No. C1608 Implausible diagnosis data

caution

If there is any problem in the CAN bus lines, an incorrect diagnosis code may be set. Prior to this diagnosis, diagnose the CAN bus lines (Refer to GROUP 54C, Trouble code diagnosis ).
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

The ASC-ECU stores diagnosis codes and failure information in the EEPROM^*.

note

^*:EEPROM (Electrical Erasable and Programmable ROM)

DIAGNOSIS CODE SET CONDITIONS

This diagnosis code 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 diagnosis code is set.
This diagnosis code 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 PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnosis

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

Q. Is the check result normal?

	Go to Step 3.

	Repair the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnosis table ). On completion, go to Step 2.

STEP 2. Diagnosis code recheck after resetting CAN bus lines

Q. Is diagnosis code No. C1608 set?

	Go to Step 3.

	The procedure is complete.

STEP 3. Battery check

Refer to GROUP 54A - Battery Test

Q. Is the battery in good condition?

	Go to Step 5.

	Go to Step 4.

STEP 4. Charging system check

Refer to GROUP 16 - Charging System

<4A9>,

<4B1>,

<BWC>,

<4B1-T/C>.

Q. Is the charging system in good condition?

	Replace the battery. Then go to Step 9.

	Repair or replace the charging system component(s).

STEP 5. Voltage measurement at the A-58 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.2 and the body earth.
OK: Approximately battery voltage

Q. Is the check result normal?

Go to Step 7.

Go to Step 6.

STEP 6. Connector check: A-58 ASC-ECU connector

Q. Is the check result normal?

	The open or short circuit may be present in the power supply circuit. Repair the wiring harness between the A-58 ASC-ECU connector terminal No.2 and the fuse No.17.

	NO : Repair the defective connector.

STEP 7. Resistance measurement at A-58 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 earth, and between the terminal No.47 and the body earth.
OK: Continuity exists (2 Ω or less)

Q. Is the check result normal?

Go to Step 9.

Go to Step 8.

STEP 8. Connector check: A-58 ASC-ECU connector

Q. Is the check result normal?

	An open circuit may be present in the earth circuit. Repair the wiring harness between the A-58 ASC-ECU connector terminal No.16 and the body earth, and between the A-58 ASC-ECU connector terminal No.47 and the body earth.

	NO : Repair the defective connector.

STEP 9. Check whether the diagnosis code is reset.

(1)Erase the diagnosis code.

(2)Turn the ignition switch to the "LOCK" (OFF) position.

(3)Turn the ignition switch to the "ON" position.

Q. Is any diagnosis code set?

	YES (Diagnosis code C1608 is set) : Replace the hydraulic unit (ASC-ECU) (Refer to ).

	YES (Diagnosis code other than C1608 is set) : Carry out the applicable troubleshooting for the diagnosis code.

	This diagnosis is complete.