Inspection Procedure 2: Electric power steering system warning display illuminates but diagnosis code is not stored.


COMMENTS ON TROUBLE SYMPTOM
The CAN bus lines may be defective. If the electric power steering system does not operate, the combination meter or the EPS-ECU may be defective.

PROBABLE CAUSES

  • Malfunction of CAN bus line
  • Defective harness wire(s) or connector(s)

    • Short or open circuit between the EPS-ECU and the ETACS-ECU, the fusible link or loose connector contact
    • Open circuit between the body earth and the EPS-ECU or loose connector contact
  • Malfunction of the ETACS-ECU
  • Malfunction of the combination meter
  • Malfunction of the EPS-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics
Use M.U.T.-III to diagnose the CAN bus lines.

Q. Is the check result normal?
Go to Step 2.
Repair the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ).

STEP 2. Check the following connector.
Check the connectors below for improper engagement, terminal damage or terminal drawn in the connector case.

  • C-222 and C-221-1 EPS-ECU connector
  • C-408 and C-417 ETACS-ECU connector
  • C-127 intermediate connector
  • No.34 and 35 fusible link <Petrol>
  • No.39 and 44 fusible link <Diesel>
  • Body earth point

Q. Is the connectors and terminals in good condition?
Go to Step 3.
Repair the defective connector(s) or terminal(s).

STEP 3. Wiring harness check
(1)Check the wiring harness between the C-222 EPS-ECU connector terminal No.11 and the fusible link No.35 <Petrol>, No.39 <Diesel> for damage or other problem.
(2)Check the wiring harness between the C-221 EPS-ECU connector terminal No.1, the C-127 intermediate connector terminal No.9 and the C-417 ETACS-ECU connector terminal No.5 for damage or other problem.
(3)Check the wiring harness between the C-408 ETACS-ECU connector terminal No.1 and the fusible link No.34 <Petrol>, No.44 <Diesel> for damage or other problem.
(4)Check the wiring harness between the C-222 EPS-ECU connector terminal No.12 and the body earth point for damage or other problem.

Q. Is the wiring harness in good condition?
Go to step 4.
Repair the defective wiring harness.

STEP 4. Voltage measurement at the ETACS-ECU connector
(1) Measure the ETACS-ECU voltage without disconnecting the connector (by backprobing).
(2)Turn the ignition switch from the "LOCK" (OFF) position to the "ON" position.
(3)Measure the voltage between the C-408 ETACS-ECU connector terminal No.1 and the C-417 ETACS-ECU connector terminal No.5.
OK: Approximately system voltage

Q. Is the check result normal?
Go to Step 5.
Check the fusible link or the ETACS-ECU and repair if necessary (Refer to GROUP 54A-ETACS ).

STEP 5. Voltage measurement at the EPS-ECU connector
(1) Measure the EPS-ECU voltage without disconnecting the connector (by backprobing).
(2)Turn the ignition switch from the "LOCK" (OFF) position to the "ON" position.
(3)Measure the voltage between the C-221 EPS-ECU connector terminal No.1 and the C-222 EPS-ECU connector terminal No.12.
OK: Approximately system voltage
(4)Measure the voltage between the C-222 EPS-ECU connector terminals No.11 and No.12.
OK: Approximately system voltage

Q. Is the check result normal?
Go to Step 6
Check the fusible link or the ETACS-ECU and repair if necessary (Refer to GROUP 54A-ETACS ).

STEP 6. Retest the system

Q. Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).
Replace the EPS-ECU (Refer to ).