Toyota Tacoma manuals

Toyota Tacoma 2015-2018 Service Manual: System Description

SYSTEM DESCRIPTION

1. DESCRIPTION

  • A part-time 2-speed VF2CM transfer uses a touch select 2-4 and high-low system, enabling the driver to switch between 2WD, H4 and L4 modes by turning the transfer position switch.
  • Through these switch signals, the 4 wheel drive control ECU actuates the shift motor in the transfer shift actuator and another shift motor in the A.D.D. actuator (differential vacuum actuator assembly).
  • When driving in 4WD at high speeds on dry pavement, the front differential oil temperature may rise excessively, resulting in oil leaks or seizures. To avoid such occurrences, the 4 wheel drive control ECU monitors the oil temperature via the front differential oil temperature sensor and provides a front differential temperature warning using a message and the warning buzzer.

2. DRIVING MODE SWITCHING PATTERN

Text in Illustration

*1

Transfer Position Switch

-

-

3. INDICATOR LIGHT, WARNING MESSAGE AND WARNING BUZZER OPERATING CONDITIONS

2WD/4WD Mode Control

Mode

4WD Indicator Light (Green)

4LO Indicator Light

Multi-information Display Message

Warning Buzzer

2WD

Not illuminated

Not illuminated

-

Not sounding

While switching between 2WD and H4

Blinking

Not illuminated

-

Not sounding

H4

Illuminated

Not illuminated

-

Not sounding

While switching between H4 and L4

Illuminated

Blinking

-

Not sounding

L4

Illuminated

Illuminated

-

Not sounding

A.D.D. Actuator malfunction

Not illuminated

Not illuminated

2WD-4WD mode change malfunction visit your dealer

Not sounding

High-Low malfunction

Status displayed*1

Rapidly blinking

-

Not sounding

Other switching malfunction*2

Not illuminated

Rapidly blinking

2WD-4WD mode change malfunction visit your dealer

Not sounding

  • *1: Displays the 2WD/4WD mode status during a malfunction
  • *2: Malfunctions not listed in "Mode" or "Control Mode"
  • 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)
Front Differential Oil Temperature Warning Control

Control Mode

2WD/4WD Mode Status

4WD Indicator Light (Green)

4LO Indicator Light

Multi-information Display Message

Warning Buzzer

Front differential oil temperature warning starts

H4

Illuminated

Not illuminated

Differential oil temp high Shift to 2WD mode Cooling time required

Sounding

L4

Illuminated

Illuminated

Differential oil temp high Shift to 2WD mode Cooling time required

Sounding

Vehicle speed limit control starts*1

H4

Illuminated

Not illuminated

Differential oil temp high Shift to 2WD mode Cooling time required

Sounding

L4

Illuminated

Illuminated

Differential oil temp high Shift to 2WD mode Cooling time required

Sounding

While switching to 2WD

H4

Illuminated

Not illuminated

Differential oil temp high Shift to 2WD mode Cooling time required

Sounding

Switching to 2WD complete

2WD

Not illuminated

Not illuminated

Differential oil temp high Cooling time required

Sounding finished

Vehicle speed limit control finished

2WD

Not illuminated

Not illuminated

-

Not sounding

Front differential oil temperature sensor malfunction

-

Not illuminated

Status displayed*2

2WD-4WD mode change malfunction visit your dealer

Not sounding

  • *1: 30 seconds after front differential oil temperature warning starts
  • *2: Displays the 2WD/4WD mode status during a malfunction

4. FUNCTION OF COMPONENTS

Components

Functions

Transfer position switch

Switches between the following 3 drive modes: 2WD, H4 and L4.

Combination meter assembly

4WD indicator light (green)

Illuminates to inform the user of 4WD mode status.

Blinks to inform the user of mode switching.

Multi-information display

Displays a malfunction message to inform the user of a system malfunction.

Displays a message to inform the user of a front differential oil temperature warning.

4LO indicator light

Illuminates to inform the user of L4 mode status.

Blinks to inform the user of mode switching.

Rapidly blinks to inform the user of a system malfunction.

Warning buzzer

Sounds to inform the user of a front differential oil temperature warning or switching condition violation.

Skid control ECU (brake actuator assembly)

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

ECM

Outputs information such as the shift lever position and engine speed to the 4 wheel drive control ECU via CAN communication.

Clutch start switch assembly (for Manual Transmission)

Detects clutch pedal depression and sends that information to the 4 wheel drive control ECU.

4 wheel drive control ECU

Detects the vehicle status from wheel speed signals, vehicle speed signals, etc. received via CAN communication, and switches to the requested 4WD mode (H4 or L4) by operating the transfer shift actuator assembly and A.D.D. actuator (differential vacuum actuator assembly) according to the operation of the transfer position switch.

Transfer shift actuator assembly

Transfer shift motor and limit switch

Operates the shift motor according to commands sent from the 4 wheel drive control ECU and switches to 4WD mode (H4 or L4).

4WD detection switch

Detects the 4WD condition and sends that information to the 4 wheel drive control ECU.

L4 detection switch

Detects the low gear position and sends that information to the 4 wheel drive control ECU.

A.D.D. actuator (differential vacuum actuator assembly)

A.D.D. shift motor and limit switch

Operates the A.D.D. shift motor according to commands sent from the 4 wheel drive control ECU and switches between 2WD and 4WD.

A.D.D. position switch

Detects the 2WD and 4WD A.D.D. positions and sends that information to the 4 wheel drive control ECU.

Oil temperature sensor

Detects the oil temperature in the front differential.

  • 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)
How To Proceed With Troubleshooting
CAUTION / NOTICE / HINT HINT: Use the following procedure listed to troubleshoot the touch select 2-4 and high-low system. *: Use the Techstream. PROCEDURE 1. ...

System Diagram
SYSTEM DIAGRAM Transmitting ECU (Transmitter) Receiving ECU Signal Communication Method 4 wheel drive control ECU Skid ...

Other materials:

Speed Sensor
Components COMPONENTS ILLUSTRATION Removal REMOVAL PROCEDURE 1. REMOVE TRANSMISSION REVOLUTION SENSOR (NT) (a) Disconnect the transmission revolution sensor (NT) connector. (b) Remove the bolt and transmission revolution sensor (NT). ...

Overhead console (Access Cab and Double Cab models)
The overhead console is useful for temporarily storing sunglasses and similar small items. Pull the lid down while pushing the knob. CAUTION ■Caution while driving Keep the overhead console closed. Injuries may result in the event of an accident or sudden braking. ■Items unsuit ...

Lost Communication with ECM / PCM "A" (U0100,U0125,U0126,U0129)
DESCRIPTION These DTCs are stored when a communication malfunction occurs between ECUs that perform pre-collision system control. DTC No. Detection Item DTC Detection Condition Trouble Area U0100 Lost Communication with ECM ...

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