Inspection Procedure

HINT:

This problem may be caused by a malfunction in the electronically controlled brake system or power steering system.

Make sure that no DTC is output for the skid control ECU, power steering ECU, or steering control ECU before proceeding with the following procedures.

If a DTC is output for any of these ECUs, first troubleshoot it and then proceed to the troubleshooting below.

1. READ VALUE USING TECHSTREAM (RECORD OF OVERHEAT) 
   1. Use the Data List to check if the record of overheat is functioning properly.

      VGRS: 

      VGRS DATA LIST REFERENCE
      
      

      Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
      Motor Overheat Record	Record of continuous overheat preventive control / Rec or Unrec	Rec or Unrec	-

      Result 

      RESULT CHART
      
      

      Result	Proceed to
      "Rec" (Record motor overheating)	A
      "Unrec" (No record of motor overheating)	B

      HINT:

      If "Rec" is displayed, reset the setting to "Unrec". Enter the VGRS menu on the tester, select record clearance, and follow the prompts to set to "Unrec".

   B: Go to step  3

   A: Go to next step 

2. CHECK HEAT PROTECTION FUNCTION FOR STEERING ACTUATOR 
   1. Turn the engine switch on (IG) and wait for 30 minutes until the steering actuator cools down.
   2. Start the engine and slowly turn the steering wheel from lock to lock (approximately 90°/sec) 3 times.

      HINT:

      If turning the steering wheel quickly while driving at low speeds, the steering angle may differ between the left and right, or the steering wheel may become off-center. However, this is not a malfunction.

   3. Check the number of turns from lock to lock.

      Result 

      RESULT CHART
      
      

      Result	Proceed to
      3.2 turns	A
      2.7 turns	B

   B: VGRS SYSTEM IS NORMAL 

   A: Go to next step 

3. CHECK STEERING EFFORT 
   1. Start the engine.
   2. Turn the steering wheel.
   3. Measure the steering effort.

      Standard steering effort: 

      Below 6.9 N*m (70 kgf*cm, 61 in.*lbf) 

      HINT:

      After completing the inspection or repair, attempt to simulate the problem and then perform "READ VALUE USING TECHSTREAM" above again to reconfirm that the problem does not occur.

   NG: GO TO POWER STEERING SYSTEM  (See POWER STEERING SYSTEM )

   OK: Go to next step 

4. CHECK STEERING ACTUATOR 
   1. Check for an abnormal noise or vibration in the steering actuator.

      OK: Neither an abnormal noise nor vibration occurs. 

   NG: GO TO STEERING WHEEL VIBRATES OR ABNORMAL NOISE IS HEARD FROM STEERING WHEEL  (See STEERING WHEEL VIBRATES OR ABNORMAL NOISE IS HEARD FROM STEERING WHEEL  )

   OK: Go to next step 

5. CHECK STEERING CONTROL ECU (POWER SOURCE CIRCUIT) 
   1. Turn the engine switch on (IG).
   2. Measure the voltage of the steering control ECU.

      Standard Voltage 

      VOLTAGE SPECIFICATION
      
      

      Tester Connection	Switch Condition	Specified Condition
      A42-3 (IG) - Body ground	Engine switch on (IG)	11 to 14 V
      A42-8 (PIG) - Body ground	Engine switch on (IG)	11 to 14 V

      Fig 1: Identifying A42 Steering Control ECU Connector Terminals

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   3. Turn the engine switch off.
   4. Measure the resistance of the steering control ECU.

      Standard Resistance 

      RESISTANCE SPECIFICATION
      
      

      Tester Connection	Condition	Specified Condition
      A42-7 (PGND) - Body ground	Always	Below 1 Ω

   NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

   OK: REPLACE STEERING CONTROL ECU  (See REMOVAL  )