Toyota Tacoma (2015-2018) Service Manual: Unable to Unlock Steering Wheel (Engine cannot Start)

Toyota Tacoma (2015-2018) Service Manual / Steering Column / Steering Lock System / Unable to Unlock Steering Wheel (Engine cannot Start)

DESCRIPTION

The steering lock actuator assembly activates the steering lock motor and moves the lock bar into the steering column to lock the steering.

The steering may not unlock when the lock bar gets stuck in the lock hole of the steering column. In this case, if the engine switch is turned on (IG) while shaking the steering wheel, as is done for a vehicle with a mechanical key, the lock bar will be unlocked. If the certification ECU (smart key ECU assembly) or ECM is replaced, the system needs to be initialized. Otherwise, the steering cannot be unlocked and the engine cannot be started.

Related Data List and Active Test Items

Problem Symptom	Data List Item	Active Test Item
Unable to unlock steering wheel (Engine cannot start)	Smart Key Unlock Request Receive L Code Check Steering Unlock	-

Problem Symptom

Data List Item

Active Test Item

Unable to unlock steering wheel

(Engine cannot start)

Smart Key

Unlock Request Receive
L Code Check
Steering Unlock

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

When using the Techstream with the engine switch off, connect the Techstream to the vehicle and turn a courtesy light switch on and off at intervals of 1.5 seconds or less until communication between the Techstream and the vehicle begins. Then select the vehicle type under manual mode and enter the following menus: Body Electrical / Smart Key. While using the Techstream, periodically turn a courtesy light switch on and off at intervals of 1.5 seconds or less to maintain communication between the Techstream and the vehicle.
Perform either of the following operations to lock/unlock the steering:
- To unlock the steering, carry the key and turn the engine switch on (ACC) or on (IG).
- To lock the steering, turn the engine switch off with the shift lever in P, and then open a door.
The steering lock system uses LIN communication. First perform the inspections in "How to Proceed with Troubleshooting" to confirm that there are no communication malfunctions before proceeding with troubleshooting (See page ).
After performing repairs, confirm that the problem does not recur.
Make sure that no DTCs are output. If any DTCs are output, proceed to the Diagnostic Trouble Code Chart (See page ).
Inspect the fuses for circuits related to this system before performing the following procedure.
When replacing the steering lock ECU (steering lock actuator or UPR bracket assembly) or certification ECU (smart key ECU assembly), registration must be performed (See page ).
When disconnecting the cable from the negative (-) battery terminal, some systems need to be initialized after the cable is reconnected (See page ).
If the steering lock ECU (steering lock actuator or UPR bracket assembly) is replaced, be sure to confirm that the steering is unlocked by turning the steering wheel to the left and right before starting the engine. This function prevents the engine from starting while the steering is locked. If the steering is locked for any reason, open and close a door with the engine switch off, and then unlock the steering by pressing the engine switch.

PROCEDURE

1.	CHECK ENGINE SWITCH (SWITCH CONDITION)

(a) 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

GO TO ENTRY AND START SYSTEM (for Start Function) (PROBLEM SYMPTOMS TABLE)

2.	CHECK INDICATOR

(a) With the engine switch on (IG), check that Steering Lock active is displayed on the multi-information display in the combination meter assembly.

Result

Result	Proceed to
Steering Lock active is displayed.	A
Steering Lock active are not displayed.	B

GO TO STEP 4

3.	CHECK STEERING LOCK

(a) Turn the steering wheel left and right, and then press the engine switch.

(b) Check that the steering is unlocked.

Result

Result	Proceed to
The steering is unlocked.	A
The steering is not unlocked.	B

END

4.	CHECK FOR DTC

(a) Using the Techstream, check if the certification ECU (smart key ECU assembly) DTC is output (See page Result ).

Result

Result	Proceed to
DTCs are not output.	A
DTCs are output.	B

GO TO DIAGNOSTIC PROCEDURE INDICATED BY OUTPUT DTC

5.	READ VALUE USING TECHSTREAM (UNLOCK REQUEST RECEIVE)

(a) Use the Data List to check if the steering lock request is functioning properly.

Smart Key

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) / OK or NG HINT: The reception state is maintained for 10 seconds. When 10 seconds or more have elapsed 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.

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) /

OK or NG

HINT:

The reception state is maintained for 10 seconds.
When 10 seconds or more have elapsed 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".

GO TO STEP 12

6.	READ VALUE USING TECHSTREAM (L CODE CHECK)

(a) Use the Data List to check if L code certification is functioning properly.

Smart Key

Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
L Code Check	Verification result between certification ECU (smart key ECU assembly) and steering lock ECU (steering lock actuator or UPR bracket assembly) / OK or NG	OK: Verification result normal NG: Verification result abnormal	When a malfunction is present: The ID code for the certification ECU (smart key ECU assembly) or steering lock ECU (steering lock actuator or UPR bracket assembly) is not registered or the certification ECU (smart key ECU assembly) or steering lock ECU (steering lock actuator or UPR bracket assembly) is malfunctioning. The steering cannot be locked. The steering cannot be unlocked (the engine cannot be started).

Tester Display

Measurement Item/Range

Normal Condition

Diagnostic Note

L Code Check

Verification result between certification ECU (smart key ECU assembly) and steering lock ECU (steering lock actuator or UPR bracket assembly) /

OK or NG

OK: Verification result normal

NG: Verification result abnormal

When a malfunction is present:

The ID code for the certification ECU (smart key ECU assembly) or steering lock ECU (steering lock actuator or UPR bracket assembly) is not registered or the certification ECU (smart key ECU assembly) or steering lock ECU (steering lock actuator or UPR bracket assembly) is malfunctioning.
The steering cannot be locked.
The steering cannot be unlocked (the engine cannot be started).

OK:

OK is displayed on the Techstream.

HINT:

Reasons for verification failure:

The steering lock ECU (steering lock actuator or UPR bracket assembly) or certification ECU (smart key ECU assembly) is malfunctioning.
There is a problem with the communication between ECUs.
An ECU is replaced, but is not registered.
An ECU is replaced with an ECU which has a code already stored in it.

GO TO STEP 11

7.	INSPECT STEERING LOCK ECU (STEERING LOCK ACTUATOR OR UPR BRACKET ASSEMBLY)

(a) Measure the resistance and voltage according to the value(s) in the table below.

Standard Resistance:

Tester Connection	Condition	Specified Condition
S45-1 (GND) - Body ground	Always	Below 1 Ω

NOTICE:

If the result is not as specified, check for looseness in the ground cable connection.

Standard Voltage:

Tester Connection	Condition	Specified Condition
S45-7 (B) - Body ground	Always	11 to 14 V

Text in Illustration

*a	Component with harness connected (Steering Lock ECU (Steering Lock Actuator or UPR Bracket Assembly))

REPAIR OR REPLACE HARNESS OR CONNECTOR

8.	CHECK HARNESS AND CONNECTOR (GROUND)

(a) Disconnect the steering lock ECU (steering lock actuator or UPR bracket assembly) connector.

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection	Condition	Specified Condition
S45-1 (GND) - Body ground	Always	Below 1 Ω

Text in Illustration

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

(d) Check the signal waveform according to the condition(s) in the table below.

Standard Frequency:

Item	Content
Tester Connection	S45-3 (IGE) - S45-1 (GND)
Tool Setting	2 V/DIV., 200 ms./DIV.
Vehicle Condition	Steering lock motor not operating → Operating → Not operating

Text in Illustration

Component with harness connected

(Steering Lock ECU (Steering Lock Actuator or UPR Bracket Assembly))

Steering Lock Motor not Operating

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).
- To lock the steering, turn the engine switch off with the shift lever in P, and then open a door.

REPLACE STEERING LOCK ECU (STEERING LOCK ACTUATOR OR UPR BRACKET ASSEMBLY)

9.	CHECK HARNESS AND CONNECTOR (STEERING LOCK ECU (STEERING LOCK ACTUATOR OR UPR BRACKET ASSEMBLY) - CERTIFICATION ECU (SMART KEY ECU ASSEMBLY))

(a) Make sure that there is no looseness at the locking part and the connecting part of the connectors.

(b) Disconnect the S45 steering lock ECU (steering lock actuator or UPR bracket assembly) connector.

(d) Check for deformation and corrosion of the connector case and terminals.

OK:

There is no deformation or corrosion of the connector case or terminals.

(e) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection	Condition	Specified Condition
S45-3 (IGE) - C29-24 (SLR+)	Always	Below 1 Ω
S45-3 (IGE) or C29-24 (SLR+) - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

10.	INSPECT STEERING LOCK ECU (STEERING LOCK ACTUATOR OR UPR BRACKET ASSEMBLY)

(a) Reconnect the steering lock ECU (steering lock actuator or UPR bracket assembly) connector.

(b) Reconnect the C29 certification ECU (smart key ECU assembly) connector.

Standard Voltage:

Tester Connection	Condition	Specified Condition
S45-3 (IGE) - Body ground	Always	11 to 14 V

Text in Illustration

*a	Component with harness connected (Steering Lock ECU (Steering Lock Actuator or UPR Bracket Assembly))

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

REPLACE STEERING LOCK ECU (STEERING LOCK ACTUATOR OR UPR BRACKET ASSEMBLY)

11.	REPLACE STEERING LOCK ECU (STEERING LOCK ACTUATOR OR UPR BRACKET ASSEMBLY)

(a) Replace the steering lock ECU (steering lock actuator or UPR bracket assembly) with a new one (See page (b) Perform registration (See page ). ).

(b) Perform registration (See page (c) Turn the engine switch on (IG). ).

(d) Use the Data List to check if L code certification is functioning properly again.

Smart Key

Tester Display

Measurement Item/Range

Normal Condition

Diagnostic Note

L Code Check

Verification result between certification ECU (smart key ECU assembly) and steering lock ECU (steering lock actuator or UPR bracket assembly) /

OK or NG

OK: Verification result normal

NG: Verification result abnormal

When a malfunction is present:

The ID code for the certification ECU (smart key ECU assembly) or steering lock ECU (steering lock actuator or UPR bracket assembly) is not registered or the certification ECU (smart key ECU assembly) or steering lock ECU (steering lock actuator or UPR bracket assembly) is malfunctioning.
The steering cannot be locked.
The steering cannot be unlocked (the engine cannot be started).

OK:

OK is displayed on the Techstream.

END

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

12.	INSPECT STEERING LOCK ECU (STEERING LOCK ACTUATOR OR UPR BRACKET ASSEMBLY)

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
S45-4 (SLP1) - Body ground	Always	11 to 14 V

Text in Illustration

*a	Component with harness connected (Steering Lock ECU (Steering Lock Actuator or UPR Bracket Assembly))

GO TO STEP 15

13.	READ VALUE USING TECHSTREAM (STEERING UNLOCK)

(a) Check that the steering is locked.

(b) Read the Data List according to the display on the Techstream.

Smart Key

Tester Display

Measurement Item/Range

Normal Condition

Diagnostic Note

Steering Unlock

State of whether steering lock ECU (steering lock actuator or UPR bracket assembly) determined steering is unlocked /

Set or Unset

Set: Steering unlocked

Unset: Steering locked

If this item displays "Unset", the steering does not unlock (engine cannot be started).

OK:

Set is displayed on the Techstream.

REPLACE STEERING LOCK ECU (STEERING LOCK ACTUATOR OR UPR BRACKET ASSEMBLY)

14.	READ VALUE USING TECHSTREAM (UNLOCK REQUEST RECEIVE)

(a) Replace the certification ECU (smart key ECU assembly) with a new one.

(b) Perform registration (See page (c) Turn the engine switch on (IG). ).

(d) Use the Data List to check if the steering lock request is functioning properly.

Smart Key

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) /

OK or NG

HINT:

The reception state is maintained for 10 seconds.
When 10 seconds or more have elapsed 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".

END

REPLACE STEERING LOCK ECU (STEERING LOCK ACTUATOR OR UPR BRACKET ASSEMBLY)

15.	CHECK HARNESS AND CONNECTOR (STEERING LOCK ECU (STEERING LOCK ACTUATOR OR UPR BRACKET ASSEMBLY) - CERTIFICATION ECU (SMART KEY ECU ASSEMBLY))

(a) Make sure that there is no looseness at the locking part and the connecting part of the connectors.

(b) Disconnect the S45 steering lock ECU (steering lock actuator or UPR bracket assembly) connector.

(d) Check for deformation and corrosion of the connector case and terminals.

OK:

There is no deformation or corrosion of the connector case or terminals.

(e) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection	Condition	Specified Condition
S45-4 (SLP1) - C29-23 (SLP)	Always	Below 1 Ω
S45-4 (SLP1) or C29-23 (SLP) - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

16.	READ VALUE USING TECHSTREAM (UNLOCK REQUEST RECEIVE)

(a) Replace the steering lock ECU (steering lock actuator or UPR bracket assembly) with a new one.

(b) Perform registration (See page (c) Turn the engine switch on (IG). ).

(d) Use the Data List to check if the steering lock request is functioning properly.

Smart Key

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) /

OK or NG

HINT:

The reception state is maintained for 10 seconds.
When 10 seconds or more have elapsed 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".

END

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

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