Toyota 4Runner manuals

Toyota 4Runner: System 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.


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



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.


Text in Illustration


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


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

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

Other materials about Toyota 4Runner:

Terminals Of Ecu
TERMINALS OF ECU 1. COMBINATION METER ASSEMBLY (a) Measure the voltage and resistance according to the value(s) in the table below. Terminal No. (Symbol) Wiring Color Terminal Description Condition ...

Problem Symptoms Table
PROBLEM SYMPTOMS TABLE HINT: Use the table below to help determine the cause of problem symptoms. If multiple suspected areas are listed, the potential causes of the symptoms are listed in order of probability in the "Suspected Area" ...

© 2016-2024 |