Toyota Tacoma (2015-2018) Service Manual: 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	-

WIRING DIAGRAM

CAUTION / NOTICE / HINT

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

NG

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

OK

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

B

GO TO STEP 4

A

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

A

END

B

4.	CHECK FOR DTC

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

Result

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

B

GO TO DIAGNOSTIC PROCEDURE INDICATED BY OUTPUT DTC

A

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.

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

GO TO STEP 12

OK

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).

OK:

OK is displayed on the Techstream.

HINT:

Reasons for verification failure:

NG

GO TO STEP 11

OK

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))

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

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))

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

(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 *a Component with harness connected (Steering Lock ECU (Steering Lock Actuator or UPR Bracket 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). To lock the steering, turn the engine switch off with the shift lever in P, and then open a door.

OK

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

NG

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.

(c) Disconnect the C29 certification ECU (smart key ECU 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

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

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.

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

OK

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

NG

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 ).

(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.

OK

END

NG

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))

NG

GO TO STEP 15

OK

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.

NG

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

OK

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".

OK

END

NG

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.

(c) Disconnect the C29 certification ECU (smart key ECU 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

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

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".

OK

END

NG

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)