Toyota 4Runner: System Description

Toyota 4Runner Service Manual / Steering / Steering Column / Steering Lock System / System Description

SYSTEM DESCRIPTION

1. DESCRIPTION

(a) The steering lock system locks or unlocks the steering by activating the steering lock bar with a motor. The steering lock ECU activates the motor based on signals from the certification ECU and power management control ECU.

(b) A Local Interconnect Network (LIN) is used for communication between different ECUs in this system.

2. FUNCTIONS OF COMPONENTS

(a) The steering lock ECU controls the system based on information from the following components:

Item	Function
Steering lock actuator assembly	Consists of a motor, lock bar, lock and unlock position sensors, etc. activated by the steering lock ECU.
Steering lock ECU	Included in the steering lock actuator assembly. This ECU activates the steering lock motor based on permission signals from the certification ECU. Records ECU verification codes.
Power management control ECU	Permits the steering lock ECU to supply power to activate the motor. Performs power supply switching control. Controls the engine switch indicator. Operates the IG2 relay.
Certification ECU	Performs key verification (checks whether the correct key is present). Controls the security indicator and the illumination of the lettering on the engine switch. Records ECU verification codes.
IG2 relay	Controlled by the power management control ECU. Signals indicating the on/off status of this relay are sent to the power management control ECU and steering lock ECU.
ID code box	Transmits a command to set or cancel the immobiliser to the ECM based on permission signals from the certification ECU. Records ECU verification codes.

3. WARNING FUNCTION OF ENGINE SWITCH INDICATOR

Text in Illustration

*1	Indicator Light

(a) The power management control ECU blinks the indicator light LED of the engine switch when any of the following problems occur in the system.

Detection Item	Indicator Blink Pattern	Indication Status	Countermeasure
Steering lock release malfunction	Blinks in green at 1-second intervals Goes off 30 seconds after blinking starts	Motor operates to release steering lock, but steering lock cannot be released (lock bar stuck in steering column).	Push engine switch while turning steering wheel to right and left
Malfunction in push button start function	Blinks in amber at 2-second intervals Goes off 15 seconds after blinking starts	Short in devices for activating motor Problem in steering lock ECU or power management control ECU	Troubleshoot by following "How to Proceed with Troubleshooting" (See page )

Parts Location

PARTS LOCATION ILLUSTRATION ILLUSTRATION ...

System Diagram

SYSTEM DIAGRAM Input and Output Signal of Each ECU Transmitting ECU (Transmitter) Receiving ECU (Receiver) Signal Communication Method P ...

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