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Inspection Procedure 2: When the heated steering wheel switch is turned on, the heated steering wheel is not activated. <Vehicles with heated steering wheel>
 
 
 
 
COMMENTS ON TROUBLE SYMPTOM
If the heated steering wheel cannot be activated when the heated steering wheel switch is turned on with the heated steering wheel deactivated, a component of the heated steering wheel, the ETACS-ECU or the power supply lines to the heated steering wheel may be defective.
 
 
 
TROUBLESHOOTING HINTS
  • Malfunction of the ETACS-ECU
  • Malfunction of heated steering wheel switch
  • Malfunction of clock spring
  • Malfunction of heated steering wheel relay
  • Defective steering wheel (incorporating heated steering wheel-ECU and heater element)
  • Defective harness wire(s) or connector(s)
    • Short or open circuit between the ETACS-ECU and the heated steering wheel-ECU, the fusible link or loose connector contact
    • Open circuit between the body ground and the heated steering wheel relay or loose connector contact
    • Open circuit between the body ground and the heated steering wheel-ECU or loose connector contact
 
 
 
DIAGNOSIS
Required Special Tools:
  • MB991223: Harness Set
  • MB992006: Extra Fine Probe
STEP 1. Using scan tool (M.U.T.-IIISE), check whether the other DTC is set.
Check that the ETACS-ECU has not set a DTC.
Is the DTC set?
Carry out the DTC procedures (Refer to GROUP 54A - ETACS-ECU ).
Go to Step 2.
 
STEP 2. Check the heated steering wheel switch.
Check the heated steering wheel switch (Refer to ).
Is the check result normal?
Go to Step 3.
Replace the heated steering wheel switch (Refer to ).
 
STEP 3. Check the clock spring.
Check whether the clock spring is in good condition (Refer to GROUP 52B - Air Bag Module and Clock Spring ).
Is the check result normal?
Go to Step 4.
Replace the clock spring (Refer to GROUP 52B - Air Bag Module and Clock Spring ).
 
STEP 4. Check the heated steering wheel relay.
Check the heated steering wheel relay (Refer to ).
Is the check result normal?
Go to Step 5.
Replace the heated steering wheel relay.
 
STEP 5. Resistance measurement at the heated steering wheel relay connector (ground terminal).
(1) Disconnect the relay, and measure at the wiring harness side.
(2) Resistance between the heated steering wheel relay connector (terminal No.1) and body ground.
OK: The resistance should be 2 ohms or less
Is the check result normal?
Go to Step 7.
Go to Step 6.
 
STEP 6. Check of open circuit in ground line between heated steering wheel relay connector (terminal No.1) and body ground.
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 7. Check of short to power supply, short to ground, and open circuit in IG1 line between ETACS-ECU and heated steering wheel relay connector.
Is the check result normal?
Go to Step 8.
Repair the connector(s) or wiring harness.
 
STEP 8. Voltage measurement at the between heated steering wheel relay connector (power supply terminal)
(1) Disconnect the relay, and measure at the wiring harness side.
(2) Measure the voltage between the heated steering wheel relay connector (terminal No.3) and body ground.
OK: The voltage should measure approximately 12 volts (battery positive voltage)
Is the check result normal?
Go to Step 11.
Go to Step 9.
 
STEP 9. Check the fusible link and relay box.
Is the check result normal?
Go to Step 10.
Repair the fusible link and relay box.
 
STEP 10. Check of short to power supply, short to ground, and open circuit in power supply line between fusible link and heated steering wheel relay connector (terminal No.3) connector
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 11. Resistance measurement at the C-311 clock spring connector (ground terminal).
(1) Disconnect the connector, and measure at the wiring harness side.
(2) Resistance between the C-311 clock spring connector (terminal No.1) and body ground.
OK: The resistance should be 2 ohms or less
Is the check result normal?
Go to Step 13.
Go to Step 12.
 
STEP 12. Check of open circuit in ground line between C-311 clock spring connector (terminal No.1) and body ground.
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 13. Check of short to power supply, short to ground, and open circuit in power supply line between heated steering wheel relay connector and C-311 clock spring connector (terminal No.3)
Is the check result normal?
Go to Step 14.
Repair the connector(s) or wiring harness.
 
STEP 14. Check of short to power supply, short to ground, and open circuit in input line between heated steering wheel relay connector and C-311 clock spring connector (terminal No.4)
Is the check result normal?
Go to Step 15.
Repair the connector(s) or wiring harness.
 
STEP 15. Retest the system
Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunctions ).
Replace the steering wheel assembly (Refer to ).