[ Model - ECLIPSE CROSS / Year - 2018 ]
2018 / ECLIPSE CROSS / EC - Workshop Manual
37 -ELECTRIC POWER STEERING (EPS) > TROUBLESHOOTING > SYMPTOM PROCEDURES > M.U.T.-III CANNOT COMMUNICATE WITH ELECTRIC POWER STEERING SYSTEM (EPS) <ECU POWER SUPPLY CIRCUIT SYSTEM CHECK>
Inspection Procedure 1: M.U.T.-IIISE cannot communicate with electric power steering system <ECU power supply circuit system check>.
 
 
 
 
COMMENTS ON TROUBLE SYMPTOM
If the M.U.T.-IIISE cannot communicate with the electric power steering system, the CAN bus lines may be defective. If the electric power steering system does not operate, the EPS-ECU or its power supply 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 EPS-ECU
 
 
 
DIAGNOSIS PROCEDURE
STEP 1. M.U.T.-IIISE CAN bus diagnostics
Use M.U.T.-IIISE to diagnose the CAN bus lines.
Is the check result normal?
Go to Step 2.
Repair the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ).
 
STEP 2. Diagnosis code recheck after resetting CAN bus lines
(1) Erase the diagnosis code.
(2) Engine start
(3) Check if the diagnosis code is set.
Is diagnosis code C1541 set?
Go to Step 3.
This diagnosis is complete.
 
STEP 3. Voltage measurement at the EPS-ECU connector (+BB, GND terminal)
(1) Measure the EPS-ECU voltage without disconnecting the connector (by backprobing).
(2) Engine start
(3) Measure the voltage between the EPS-ECU connector (+B terminal) and the EPS-ECU connector (GND terminal) or body earth.
OK: Approximately system voltage
Is the check result normal?
Go to Step 6.
Go to Step 4.
 
STEP 4. Check the fusible link.
Is the check result normal?
Go to Step 5.
Repair the fusible link.
 
STEP 5. Check of short to power supply, short to earth, and open circuit in +B line between fusible link and EPS-ECU connector
notePrior to the wiring harness inspection, check intermediate connector and repair if necessary.
Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunctions ).
Repair the fusible link, connector(s) or wiring harness.
 
STEP 6. Voltage measurement at the EPS-ECU connector (IG1, GND terminal)
(1) Measure the EPS-ECU voltage without disconnecting the connector (by backprobing).
(2) Engine start
(3) Measure the voltage between the EPS-ECU connector (IG1 terminal) and the EPS-ECU connector (GND terminal) or body earth.
OK: Approximately system voltage
Is the check result normal?
Go to Step 8.
Go to Step 7.
 
STEP 7. Check of short to power supply, short to earth, and open circuit in IG1 line between EPS-ECU connector and ETACS-ECU connector
notePrior to the wiring harness inspection, check joint connector and repair if necessary.
Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunctions ).
Repair the connector(s) or wiring harness.
 
STEP 8. Resistance measurement at the EPS-ECU connector (GND terminal).
(1) Disconnect the connector, and measure at the wiring harness side.
(2) Resistance between the EPS-ECU connector (GND terminal) and body earth
OK: Continuity exists (2 Ω or less)
Is the check result normal?
Go to Step 10.
Go to Step 9.
 
STEP 9. Check of open circuit in GND line between EPS-ECU connector and body earth.
notePrior to the wiring harness inspection, check intermediate connector and repair if necessary.
Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunctions ).
Repair the connector(s) or wiring harness.
 
STEP 10. Retest the system
Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunctions ).
Replace the EPS-ECU (Refer to ).