Toyota CH-R Service Manual: Terminals Of Ecu




Component without harness connected

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



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

Terminal No. (Symbol)


Wiring Color

Terminal Description


Specified Condition

Related Data List Item

F78-1 (GND) - Body ground


W-B - Body ground



Below 1 Ω


F78-3 (IGEI) - F78-1 (GND)


P - W-B

Steering lock motor activation command signal (motor activation command signal sent from certification ECU (smart key ECU assembly))

Any door opened when conditions below met, and then steering lock motor activated:

  • Shift lever in P
  • Steering lock unlocked in advance by carrying key and turning engine switch on (IG)
  • After above conditions met, engine switch turned off

Pulse generation (see waveform)

Smart Key
  • Power Supply Short
  • Unlock Request Receive
  • Lock Request Receive

F78-4 (SLP1) - F78-1 (GND)


G - W-B

Steering lock bar position signal (output signal from steering unlock sensor)

Steering locked → unlocked

11 to 14 V → Below 1.5 V

Smart Key
  • Sensor Value

F78-5 (LIN) - F78-1 (GND)


V - W-B

LIN communication line



Smart Key
  • Steering Lock Start Cond

F78-6 (IG2) - F78-1 (GND)


B - W-B

Power source mode signal (IG2 power supply input for entire steering lock actuator or upper bracket assembly)*1

Engine switch off → engine switch on (IG)

Below 1 V → 11 to 14 V


F78-7 (B) - Body ground


L - Body ground

Power source*1


11 to 14 V


  • *1: When there is a problem with the power source input, the certification ECU (smart key ECU assembly) may store DTC B2786.


There is 1 motor and 2 sensors built into the steering lock actuator or upper bracket assembly.


  • 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.

(1) Waveform


Steering Lock Motor not Operating


Steering Lock Motor Operating



Tester Connection

F78-3 (IGEI) - F78-1 (GND)

Tool Setting

2 V/DIV., 200 ms./DIV.

Vehicle Condition

Steering lock motor not operating → Operating → Not operating

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