NO.2 HEATED STEERING WHEEL SYSTEM OPERATES CONSTANTLY [HEATED STEERING WHEEL]

id0603a3951200

Description
Heated steering wheel warms steering wheel even though heated steering wheel switch is off
Possible Causes
Heated steering wheel switch is always ON
•  Heated steering wheel switch malfunction
•  Clock spring malfunction
Heated steering wheel control unit falsely detects heated steering wheel switch is ON
•  Heated steering wheel control unit malfunction
•  Clock spring malfunction
•  Short circuit in wiring harness between the following terminal:
?  Heated steering wheel control unit terminal C and indicator unit terminal I
•  When performing an asterisked (*) troubleshooting inspection, shake the wiring harness and connectors while performing the inspection to discover whether poor contact points are the cause of any intermittent malfunctions.
If there is a problem, check to make sure connectors, terminals and wiring harnesses are connected correctly and undamaged.

Diagnostic Procedure

STEP

INSPECTION

ACTION
1
DETERMINE IF THE MALFUNCTION CAUSE IS THE HEATED STEERING WHEEL SWITCH
•  Switch the ignition OFF (LOCK).
•  Disconnect the indicator unit connector.
•  Switch the ignition ON (engine off or on).
•  Is the heated steering wheel system operating?
Yes
Go to the next step.
No
Replace the indicator unit, then go to step 5.
(See INDICATOR UNIT REMOVAL/INSTALLATION.)
2*
DETERMINE IF MALFUNCTION CAUSE IS HEATED STEERING WHEEL CONTROL UNIT
Warning
•  Handling the component parts improperly can accidentally operate (deploy) the air bag module, which may seriously injure you. Read the service warnings/cautions and the workshop manual before handling the air bag system components.
•  Switch the ignition to off (LOCK).
•  Disconnect the negative battery terminal and wait for 1 min or more.
•  Remove the driver-side air bag module connector.
•  Remove the steering wheel.
•  Connect the negative battery terminal.
•  Switch the ignition ON (engine off or on).
•  Measure the voltage at clock spring connector 6 terminal 7B.
•  Is the voltage B+?
Yes
Go to the next step.
No
Go to step 4.
3*
DETERMINE IF MALFUNCTION CAUSE IS HEATED STEERING WHEEL CONTROL UNIT
•  Disconnect the negative battery terminal.
•  Remove the clock spring.
•  Connect the negative battery terminal.
•  Switch the ignition ON (engine off or on).
•  Measure the voltage at clock spring connector 3 terminal 6B (vehicle wiring harness side).
•  Is the voltage B+?
Yes
•  Refer to the wiring diagram and verify if there is a common connector between the following terminals.
?  clock spring connector 3 terminal 6B and indicator unit terminal I
If there is a common connector:
•  Inspect the common connector and terminals for corrosion, damage, or disconnection and the common wiring harnesses for short to power supply to determine the malfunctioning location.
•  Repair or replace the wiring harness which is shorted to the power supply.
If there is no common connector:
•  Repair or replace the wiring harness which is shorted to the power supply.
•  Go to the next step.
No
Replace the clock spring, then go to the next step.
(See CLOCK SPRING REMOVAL/INSTALLATION.)
4*
DETERMINE IF MALFUNCTION CAUSE IS HEATED STEERING WHEEL CONTROL UNIT
•  Reconnect the clock spring connector 3 and 6.
•  Disconnect the heated steering wheel control unit connector.
•  Connect the negative battery terminal.
•  Switch the ignition ON (engine off or on).
•  Measure the voltage at heated steering wheel control unit terminal C (vehicle wiring harness side).
•  Is the voltage B+?
Yes
•  Repair or replace the wiring harness which is shorted to the power supply.
•  Go to the next step.
No
Replace the heated steering wheel control unit, then go to the next step.
(See HEATED STEERING WHEEL CONTROL UNIT REMOVAL/INSTALLATION.)
5
VERIFY IF MALFUNCTION CAUSE IS CORRECTED
•  Reconnect all the disconnected connectors.
•  Switch the ignition ON (engine off or on).
•  Operate the heated steering wheel switch to turn on the heated steering wheel system.
•  Does the heated steering wheel system operate normally?
Yes
Troubleshooting completed. (Explain the contents of the servicing to the customer.)
No
Verify the malfunction symptom in the symptom troubleshooting chart and perform the other applicable malfunction diagnosis.
(See SYMPTOM TROUBLESHOOTING [HEATED STEERING WHEEL].)