Unable to Unlock Steering Wheel (Engine cannot Start): Procedure

NG → REPAIR CIRCUITS INDICATED BY OUTPUT DTCS 

OK: Go to next step 

1. Check the power source mode change.
   1. When the key is inside the vehicle and the shift lever is in P, check that pressing the engine switch with the brake pedal released causes the power source mode to change as follows:

      OK

      Off → on (ACC) → on (IG) → off

NG → See step   15 

OK: Go to next step 

1. Use the Data List to check if the steering lock request is functioning properly.
   SMART ACCESS
   
   

   Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
   Unlock Request Receive	Reception state of steering unlock request signal by certification ECU (smart key ECU assembly) and sent to ID code box (immobilizer code ECU) / OK or NG HINT:  The reception state is maintained for 10 seconds. When 10 seconds or more elapse after receiving the signal, the item changes to "NG".	OK: Within 10 seconds of turning engine switch on (IG) or on (ACC) or starting engine NG: Except above	If the unlock signal has not been received, the engine cannot be started. If this item does not change to "OK" even though the steering unlock conditions are met, the certification ECU (smart key ECU assembly) may be malfunctioning.

   OK

   Within 10 seconds of turning the engine switch on (ACC) or on (IG) or starting the engine, the Data List item changes to "OK".

NG → See step   7 

OK: Go to next step 

1. Measure the voltage according to the value(s) in the table below.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   TEXT IN ILLUSTRATION
   
   

   *a

   Component with harness connected (Certification ECU (Smart Key ECU Assembly))

   -

   -

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   N93-25 (P) - A34-11 (E)	Shift lever in P	9 V or higher
   	Shift lever not in P	1.5 V or less

NG → See step   12 

OK: Go to next step 

1. Disconnect the steering lock ECU connector.
2. Measure the resistance and voltage according to the value(s) in the table below.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   N24-1 (GND) - Body ground	Always	Below 1 Ω

   NOTE:

   If the result is not as specified, check for looseness in the connection which leads to ground.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   N24-7 (B) - Body ground	Always	11 to 14 V

   TEXT IN ILLUSTRATION
   
   

   *a	Front view of wire harness connector (to Steering Lock ECU (Steering Lock Actuator Assembly))

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Reconnect the steering lock ECU connector.
2. Check the signal waveform according to the condition(s) in the table below.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   STANDARD FREQUENCY
   
   

   Item	Content
   Tester Connection	N24-3 (IGE) - N24-1 (GND)
   Tool Setting	2 V/DIV., 200 ms./DIV.
   Vehicle Condition	Steering lock motor not operating → Steering lock motor operating → Steering lock motor not operating

   TEXT IN ILLUSTRATION
   
   

   *a	Component with harness connected (Steering Lock ECU (Steering Lock Actuator Assembly))
   *b	Steering lock motor not operating
   *c	Steering lock motor operating

   HINT: 

   • When taking measurements when the lock motor is stopped, it is not necessary to perform any operations.
   • In order to take measurements when the lock motor is operating, perform either of the following operations:
     • To unlock the steering, carry the key and turn the engine switch on (ACC) or on (IG) with the shift lever in P.
     • To lock the steering, turn the engine switch off with the shift lever in P, and then open a door.

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK → See step   17 

NG → See step   10 

OK: Go to next step 

NG → See step   11 

OK: Go to next step 

NG → See step   14 

OK → END 

NG → See step   16 

OK → END 

NG → See step   18 

OK → END 

1. Disconnect the N49 transmission floor shift assembly connector.
2. Disconnect the N93 certification ECU (smart key ECU assembly) connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   N49-3 (P2) - N93-25 (P)	Always	Below 1 Ω
   N49-3 (P2) - Body ground		10 kΩ or higher
   N93-25 (P) - Body ground

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Reconnect the transmission floor shift assembly connector.
2. Measure the voltage according to the value(s) in the table below.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   N49-3 (P2) - Body ground	Shift lever in P	9 V or higher
   	Shift lever not in P	1.5 V or less

   RESULT
   
   

   Result		Proceed to
   OK		A
   NG	for A760H	B
   	for A760E	C

   TEXT IN ILLUSTRATION
   
   

   *a	Component with harness connected (Shift lock control ECU (transmission floor shift assembly))

B → See step   19 

C → See step   21 

A → See step   20