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Inspection Procedure: Steering wheel sensor power supply system.
 
 
cautionWhen the steering column switch assembly (Integrated with steering wheel sensor) is replaced, always carry out calibration to make ASC-ECU learn the neutral point (Refer to ).
 
 
OPERATION
  • The steering wheel sensor contains the power supply circuit (IG terminal) for itself. When the ignition switch (IG1) is turned ON, the voltage is applied to the relay incorporated in the ETACS-ECU to turn ON the relay, and the power is supplied from the fusible link through the multi-purpose fuse.
  • When malfunction occurs in steering wheel sensor power supply, the communication with scan tool (M.U.T.-IIISE) becomes unavailable.
 
 
PROBABLE CAUSES
  • Battery failure
  • Improper tightening of battery terminal
  • Charging system failed
  • Damaged harness wires and connectors
  • Fuse and fusible link malfunction
  • Improper tightening of ground bolt
  • Malfunction of the steering column switch assembly (Integrated with steering wheel sensor)
 
 
DIAGNOSIS
STEP 1. Check the battery.
Refer to GROUP 54A - Battery Test .
Is the battery in good condition?
Go to Step 3.
Charge or replace the battery. Then go to Step 2.
 
STEP 2. Check the charging system.
Refer to GROUP 16 - Charging System .
Is the charging system in good condition?
Go to Step 3.
Repair or replace the charging system component(s).
 
STEP 3. Measure the resistance at the steering wheel sensor connector.
(1) Connector check: the steering wheel sensor connector and the junction block
(2) Disconnect the steering wheel sensor connector.
(3) Measure the resistance between the IG terminal and body ground.
OK: No continuity
Is the check result normal?
Go to Step 4.
The power supply circuit may be short. Repair the wiring harness wires or connectors between the steering wheel sensor connector IG terminal and the junction block.
 
STEP 4. Measure the voltage at the steering wheel sensor connector.
(1) Disconnect the steering wheel sensor connector.
(2) Ignition switch: "ON"
(3) Measure the voltage between the IG terminal and body ground.
OK: System voltage
Is the check result normal?
Go to Step 5.
The power supply circuit may be open. Repair the wiring harness wires or connectors between the steering wheel sensor connector IG terminal and the junction block.
 
STEP 5. Measure the resistance at the column switch connector.
(1) Disconnect the column switch connector.
(2) Measure the resistance between the GND terminal and body ground.
OK: Continuity exists (2 Ω or less).
Is the check result normal?
Go to Step 6.
The ground circuit may be open. Repair the wiring harness wires or connectors between the column switch connector GND terminal and body ground.
 
STEP 6. Retest the system.
Make sure that the scan tool (M.U.T.-IIISE) cable is properly connected and the V.C.I. switch is ON.
Is the communication with scan tool (M.U.T.-IIISE) possible?
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).
Replace the steering column switch assembly (Integrated with steering wheel sensor) (Refer to GROUP 54A - Column Switch ).