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 |
|
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 ...
Other materials:
Diagnostic Trouble Code Chart
DIAGNOSTIC TROUBLE CODE CHART
Dynamic Radar Cruise Control System
DTC No.
Detection Item
Link
C1A02
Vehicle Information Not Obtained
C1A0A
Front Radar Sensor Region Code Mismatch
...
Parts Location
PARTS LOCATION
ILLUSTRATION
ILLUSTRATION
ILLUSTRATION
ILLUSTRATION
ILLUSTRATION
...
Installation
INSTALLATION
PROCEDURE
1. INSTALL EXHAUST MANIFOLD SUB-ASSEMBLY LH
(a) Install a new gasket to the cylinder head LH.
NOTICE:
Be careful of the installation direction.
(b) Temporarily install the exhaust manifold sub-assembly LH with the 4 nuts.
(c) Tighten the 4 nuts in the sequenc ...
