Toyota Tacoma manuals

Toyota Tacoma 2015-2018 Service Manual: System Description

SYSTEM DESCRIPTION

1. DESCRIPTION

  • The differential system (w/ Differential Lock) directly connects the rear left and right wheels so that even if one wheel slips while driving where drive torque transmission is difficult (such as on sand), the drive torque of the other wheel is ensured and traction is provided in emergencies.
  • for 4WD:

    When the transfer is in L4 and the differential lock switch is operated, the 4 wheel drive control ECU supplies power to the solenoid to switch the rear differential from free to locked, and cuts power to switch the rear differential from locked to free.

    for 2WD:

    When the differential lock switch is operated, the 4 wheel drive control ECU supplies power to the solenoid to switch the rear differential from free to locked, and cuts power to switch the rear differential from locked to free.

2. INDICATOR LIGHT AND BUZZER OPERATING CONDITIONS

(a) for 4WD:

Mode

2WD/4WD Mode Status

Rear Differential Lock Indicator Light

4WD Indicator Light (Green) and 4LO Indicator Light

Buzzer

Rear differential free

2WD or H4

Not illuminated

Turned off or illuminated to display 2WD or H4 mode status

Not sounding

Rear differential free

L4

Not illuminated

Illuminated

Not sounding

Rear differential switching between free and locked

L4

Blinking

Illuminated

Not sounding

Rear differential locked

L4

Illuminated

Illuminated

Not sounding

Rear differential lock malfunction

2WD, H4 or L4

Rapidly blinking

Illuminated

Not sounding

  • Blinking: Blinks at 0.5 second intervals (0.5 seconds on and 0.5 seconds off)
  • Rapidly blinking: Blinks at 0.25 second intervals (0.25 seconds on and 0.25 seconds off)

(b) for 2WD:

Mode

Rear Differential Lock Indicator Light

Buzzer

Rear differential free

Not illuminated

Not sounding

Rear differential switching between free and locked

Blinking

Not sounding

Rear differential locked

Illuminated

Not sounding

Rear differential lock malfunction

Rapidly blinking

Not sounding

  • Blinking: Blinks at 0.5 second intervals (0.5 seconds on and 0.5 seconds off)
  • Rapidly blinking: Blinks at 0.25 second intervals (0.25 seconds on and 0.25 seconds off)

3. FUNCTION OF COMPONENTS

Components

Functions

Differential lock coil

Switches the rear differential between free and locked according to commands from the 4 wheel drive control ECU.

Differential Lock Indicator Switch

Detects the rear differential locked condition and sends that information to the 4 wheel drive control ECU.

Combination meter assembly

  • Rear differential lock indicator light
  • Buzzer

Illuminates to inform the user of the locked condition. Blinks to inform the user of switching between free and locked. Rapidly blinks to inform the user of a system malfunction.

for 4WD:

When the differential lock switch is pressed while not in L4, the indicator light blinks 3 times and the buzzer sounds 3 times.

HINT:

When the rear differential is in the locked condition, ABS, VSC and TRAC are prohibited.

Differential lock switch

Selects free or locked for the rear differential.

Skid control ECU (brake actuator assembly)

Outputs wheel speed signals to the 4 wheel drive control ECU via CAN communication.

4 wheel drive control ECU

Detects the vehicle status according to signals such as the wheel and vehicle speed signals received via CAN communication, and operates or stops the differential lock coil and switches the rear differential between locked and free according to the differential lock switch signal.

  • Blinking: Blinks at 0.5 second intervals (0.5 seconds on and 0.5 seconds off)
  • Rapidly blinking: Blinks at 0.25 second intervals (0.25 seconds on and 0.25 seconds off)
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 lis ...

Diagnosis System
DIAGNOSIS SYSTEM 1. DESCRIPTION The 4 wheel drive control ECU records DTCs when the ECU detects a malfunction in the ECU itself or in system circuits. The DTCs can be read through the DLC3 of the ...

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Terminals Of Ecu
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