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 - CAN Bus Diagnostics Table ).
Whenever ECU is replaced, ensure that the CAN bus lines are normal.
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 Diagnostics 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 - On-vehicle Service/Alternator Output Line
Voltage Drop Test .
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 ASC-ECU connector
(1)Disconnect the connector, and measure at the wiring harness side.
(2)Measure the voltage between the +BV terminal and the body earth. OK: Approximately system voltage
Q.
Is the check result normal?
Go to Step 7
Go to Step 6
STEP 6. Check of short to power supply, short to earth, and open circuit
in +BV line between fusible link and ASC-ECU connector
Q.
Is the check result normal?
Go to Step 7
NO : Repair the fusible link, connector(s) or wiring harness.
STEP 7. Resistance measurement at ASC-ECU connector
(1)Disconnect the connector, and measure at the wiring harness side.
(2)Resistance between the GND1 terminal and the body earth, and between the GND2 terminal
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. Check of open circuit in GND1, GND2 line between ASC-ECU connector
and body earth
Q.
Is the check result normal?
Go to Step 9
NO : Repair the connector(s) or wiring harness.
STEP 9. Check whether the diagnosis code is reset.
(1)Erase the diagnosis code.
(2)Drive the vehicle at 20 km/h or higher.
note
The ABS warning lamp does not turn OFF in some cases unless the vehicle runs at 20 km/h
or higher.
Q.
Is diagnosis code No. C1608 set?
Replace the hydraulic unit (integrated with ASC-ECU) (Refer to ).
Then go to step 10.
Go to Step 11
STEP 10. Check whether the diagnosis code is reset.
(1)Erase the diagnosis code.
(2)Drive the vehicle at 20 km/h or higher.
note
The ABS warning lamp does not turn OFF in some cases unless the vehicle runs at 20 km/h
or higher.
Q.
Is diagnosis code No. C1608 set?
Return to Step 1.
NO : Go to Step 11
STEP 11. Check the other diagnosis code.
(1)Erase the diagnosis code.
(2)Drive the vehicle at 20 km/h or higher.
note
The ABS warning lamp does not turn OFF in some cases unless the vehicle runs at 20 km/h
or higher.
Q.
Is any diagnosis code set?
Carry out the applicable troubleshooting for the diagnosis code (Refer to ).
Go to Step 3
Repair the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table 
).
On completion, go to Step 2.
: Go to Step 11