Inspection Procedure 3: The steering has become heavy, but electric power steering warning display does not illuminate. (Power supply voltage assist fall)


COMMENTS ON TROUBLE SYMPTOM
Intermittent failure may be present in the power supply system. Check the battery and the alternator to confirm that normal direct voltage flows.

PROBABLE CAUSES

  • Malfunction of CAN bus line
  • Defective battery
  • Charging system failed
  • 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. M.U.T.-III data list
Check the following service data .

  • Item No. A11: Odometer :rec.A1
  • Item No. A12: Motor current (target) :rec.A1
  • Item No. A13: Motor cur. (unltd target) :rec.A1
  • Item No. A14: Motor current :rec.A1
  • Item No. A15: Vehicle speed :rec.A1
  • Item No. A21: Odometer :rec.A2
  • Item No. A22: Motor current (target) :rec.A2
  • Item No. A23: Motor cur. (unltd target) :rec.A2
  • Item No. A24: Motor current :rec.A2
  • Item No. A25: Vehicle speed :rec.A2
  • Item No. A31: Odometer :rec.A3
  • Item No. A32: Motor current (target) :rec.A3
  • Item No. A33: Motor cur. (unltd target) :rec.A3
  • Item No. A34: Motor current :rec.A3
  • Item No. A35: Vehicle speed :rec.A3
  • Item No. A41: Odometer :rec.A4
  • Item No. A42: Motor current (target) :rec.A4
  • Item No. A43: Motor cur. (unltd target) :rec.A4
  • Item No. A44: Motor current :rec.A4
  • Item No. A45: Vehicle speed :rec.A4
  • Item No. A51: Odometer :rec.A5
  • Item No. A52: Motor current (target) :rec.A5
  • Item No. A53: Motor cur. (unltd target) :rec.A5
  • Item No. A54: Motor current :rec.A5
  • Item No. A55: Vehicle speed :rec.A5
  • Item No. B11: Odometer:rec.V1
  • Item No. B12: Power relay voltage:rec V1
  • Item No. B13: Vehicle speed:rec.V1
  • Item No. B21: Odometer:rec.V2
  • Item No. B22: Power relay voltage:rec V2
  • Item No. B23: Vehicle speed:rec.V2
  • Item No. B31: Odometer:rec.V3
  • Item No. B32: Power relay voltage:rec V3
  • Item No. B33: Vehicle speed:rec.V3
  • Item No. B41: Odometer:rec.V4
  • Item No. B42: Power relay voltage:rec V4
  • Item No. B43: Vehicle speed:rec.V4
  • Item No. B51: Odometer:rec.V5
  • Item No. B52: Power relay voltage:rec V5
  • Item No. B53: Vehicle speed:rec.V5

Q. Is the check result normal?
Go to Step 3.
Check the combination meter and repair if necessary (Refer to GROUP 54A-combination meter ). Then go to Step 5.

STEP 3. Check the battery voltage.
Start the engine and measure the battery voltage (Refer to GROUP 54A - Battery Test ).

Q. Is the check result normal?
Go to Step 4.
Check the battery and repair if necessary (Refer to GROUP 54A - Charging System , Removal and Installation ).

STEP 4. Check the charging system.
Start the engine and measure the charging system (Refer to GROUP 16 - Charging System ).

Q. Is the check result normal?
Go to Step 5.
Check the charging system and repair if necessary (Refer to GROUP 16 - Alternator Assembly <4B1, 4J1> or <4N1>).

STEP 5. 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 ).