Toyota 4Runner manuals

Toyota 4Runner: Fail-safe Chart

FAIL-SAFE CHART

1. FAIL-SAFE FUNCTION

(a) When communication fails in any of the main wires (communication lines) due to a short circuit or other causes, the fail-safe function, which is specified for each system, operates to prevent the system from malfunctioning.

(b) The table below shows the effects on each system when communication is impossible. For further details, refer to each system.

Function

  1. Control Master
  2. System Related

Fail-safe Function System Behavior

User Notification

Diagnosis Code

Engine-related Indicators

(The system estimates the oil deterioration level and the indicators indicate on the meter that an oil change is necessary, etc.)

  1. ECM
  2. Combination meter assembly
  • The indicator lights do not turn on.
  • Cannot clear the meter display.

The engine-related indicator lights do not turn on.

-

Electrical Load Control

(Performs idle up according to the electrical load.)

  1. ECM
  2. Air conditioning amplifier assembly, Main body ECU (multiplex network body ECU)

Idle up according to the electrical load is not performed.

The idle speed changes.

-

Air Conditioning-linked Control

(Performs idle up according to the compressor load.)

  1. ECM
  2. Air conditioning amplifier assembly, Power management control ECU

Air conditioning-linked control does not operate.

The air conditioning does not operate.

-

PTC Heater

(Performs idle up according to requests from the PTC heater or heater system.)

  1. ECM
  2. Air conditioning amplifier assembly

The PTC heater does not operate.

The idle speed changes and heater performance deteriorates.

-

Eco Driving Indicator

(Displays information to the driver to encourage "ecodriving".)

  1. ECM
  2. Combination meter assembly
  • The indicator light does not turn on.
  • The display of all information stops.

The eco driving indicator light does not turn on.

-

Integrated Control (VSC)

(Estimates the driver requested torque based on accelerator pedal operation and performs torque characteristic control according to driving conditions so that drivability, acceleration performance and acceleration feeling are improved.)

  1. ECM
  2. Skid control ECU (brake actuator assembly) or Skid control ECU (master cylinder solenoid), Yaw rate sensor assembly, Steering angle sensor (spiral cable sub-assembly)

Integrated control is not performed.

Nothing

-

ECT System Indicators

(Indicate shift position, states of switches, system modes, etc.)

  1. ECM
  2. Combination meter assembly, Drive monitor switch

-

ECT system indicator lights do not turn on.

-

AI-SHIFT Control

(Controls the A/T in order to improve engine braking power and acceleration feel.)

  1. ECM
  2. Skid control ECU (brake actuator assembly) or Skid control ECU (master cylinder solenoid)

AI-SHIFT control does not operate.

Nothing

-

Coast Downshift

(Changes the coast downshift point based on the air conditioning load and performs upshift delay according to air conditioning or heater requests.)

  1. ECM
  2. Air conditioning amplifier assembly

Coast downshift does not operate.

Coast downshift shock becomes stronger.

-

Cruise Control

(Adjusts the engine throttle valve opening amount automatically to maintain the vehicle speed.)

  1. ECM
  2. Skid control ECU (brake actuator assembly) or Skid control ECU (master cylinder solenoid), Combination meter assembly

Cruise control does not operate.

The CRUISE main indicator light and CRUISE SET indicator light blink.

-

ABS Control

(Controls the ABS according to the yaw rate sensor signal.)

  1. Skid control ECU (brake actuator assembly) or Skid control ECU (master cylinder solenoid)
  2. Yaw rate sensor assembly, Four wheel drive control ECU

The ABS does not operate.

The ABS indicator light turns on.

U0073

U0114

U0123

U0124

TRC Control

(Controls the brakes and engine torque during acceleration slip.)

  1. Skid control ECU (brake actuator assembly) or Skid control ECU (master cylinder solenoid)
  2. ECM, Four wheel drive control ECU

TRC does not operate.

The SLIP indicator light turns on.

U0073

U0100

U0114

U0123

U0124

U0126

VSC Control

(Controls VSC according to yaw rate sensor and steering angle sensor signals.)

  1. Skid control ECU (brake actuator assembly) or Skid control ECU (master cylinder solenoid)
  2. ECM, Yaw rate sensor assembly, Steering angle sensor (spiral cable sub-assembly), Four wheel drive control ECU

VSC does not operate.

The SLIP indicator light turns on.

U0073

U0100

U0114

U0123

U0124

U0126

Steering Sensor

(Detects the steering wheel angle.)

  1. Steering angle sensor (spiral cable sub-assembly)
  2. Skid control ECU (brake actuator assembly) or Skid control ECU (master cylinder solenoid)

-

The SLIP indicator light turns on.

-

Vehicle Speed Information Input

(Controls solenoid current [PPS solenoid] according to the vehicle speed, steering angle, steering speed and engine speed.)

  1. Power steering ECU assembly
  2. Skid control ECU (brake actuator assembly) or Skid control ECU (master cylinder solenoid)

Changes to the 40 km/h (25 mph) assist map to perform control.

The PPS indicator light turns on.

U0129

Steering Wheel Angle Information Input

(Controls solenoid current [PPS solenoid] according to the vehicle speed, steering angle, steering speed and engine speed.)

  1. Power steering ECU assembly
  2. Steering angle sensor (spiral cable sub-assembly)

Steering angle is fixed at 0 degrees and the steering angle speed is fixed at 360 degrees per second.

Nothing

U0126

Engine Speed Information Input

(Controls solenoid current [PPS solenoid] according to the vehicle speed, steering angle, steering speed and engine speed.)

  1. Power steering ECU assembly
  2. ECM

Control is performed using a fixed value of 0 rpm.

Nothing

U0100

TC DTC Output Service

(Outputs a DTC in response to a DTC output request from the combination meter assembly.)

  1. Combination meter assembly
  2. ECM, Airbag sensor assembly

The TC service function stops.

Nothing

-

Event Data Recorder (EDR)

(Records conditions such as the vehicle speed, the amount the accelerator pedal is depressed and the shift lever position when the event data recorder recording conditions are met.)

  1. Airbag sensor assembly
  2. ECM

Data is not recorded.

Nothing

-

SRS Warning Light Control

(Turns the warning light on/off.)

  1. Combination meter assembly
  2. Airbag sensor assembly

-

The SRS warning light turns on.

-

Collision Detection Signal (for Fuel-cut)

(Notifies the system of a collision in order to perform fuel-cut when a vehicle collision occurs.)

  1. ECM
  2. Airbag sensor assembly

-

Nothing

-

Seat Belt Warning Light Control

(Turns the seat belt warning light on/off.)

  1. Combination meter assembly, Main body ECU (multiplex network body ECU)
  2. Airbag sensor assembly

-

Nothing

-

Air Conditioning System Control

(Controls the air conditioning according to the engine coolant temperature information, controls the PTC heater operation according to the PTC heater operation permission information.)

  1. Air conditioning amplifier assembly
  2. ECM, Combination meter assembly, Main body ECU (multiplex network body ECU)
  • Maintains the current conditions.
  • PTC control does not operate.

Nothing

U0100

U0142

U0155

Speedometer

(Controls the speedometer according to the vehicle speed signals.)

  1. Combination meter assembly
  2. Skid control ECU (brake actuator assembly) or Skid control ECU (master cylinder solenoid)

0 km/h (0 mph) is indicated.

Behavior during a communication failure alerts the user.

U0129

Tachometer

(Controls the tachometer according to the engine speed signals.)

  1. Combination meter assembly
  2. ECM

0 rpm is indicated.

Behavior during a communication failure alerts the user.

U0100

Engine Coolant Temperature Gauge

(Controls the temperature gauge according to the temperature signals.)

  1. Combination meter assembly
  2. ECM

The temperature gauge needle is at the middle of the "C" mark or below.

Nothing

U0100

Fuel Receiver Gauge

(Controls the fuel gauge according to the vehicle condition determined by the ST signal, vehicle speed signal and fuel amount.)

  1. Combination meter assembly
  2. ECM, Skid control ECU (brake actuator assembly) or Skid control ECU (master cylinder solenoid)
  • Operates the same as when the vehicle is stopped.
  • Operates with ST set to off.

Nothing

U0100

U0129

ODO/TRIP Meter

(Calculates and indicates the driven distance according to the pulse count of the vehicle speed pulse signal.)

  1. Combination meter assembly
  2. Skid control ECU (brake actuator assembly) or Skid control ECU (master cylinder solenoid)

The calculation stops and the last displayed value remains.

Nothing

U0129

Shift Display

(Displays the shift information according to the shift position signal.)

  1. Combination meter assembly
  2. ECM

The shift display turns off.

Nothing

U0100

Telltale

(Controls indicator illumination and blinking according to the CAN signals and direct line input signals.)

  1. Combination meter assembly
  2. ECM, Skid control ECU (brake actuator assembly) or Skid control ECU (master cylinder solenoid), Power steering ECU assembly, Airbag sensor assembly, Certification ECU (smart key ECU assembly), Main body ECU (multiplex network body ECU), Four wheel drive control ECU, Stabilizer control ECU

-

The indicator or warning lights turn on.

U0100

U0129

U0131

U0142

U0151

Buzzer

(Controls the sounding of buzzers according to the CAN signals and direct line input signals.)

  1. Combination meter assembly
  2. ECM, Skid control ECU (brake actuator assembly) or Skid control ECU (master cylinder solenoid), Airbag sensor assembly, Certification ECU (smart key ECU assembly), Main body ECU (multiplex network body ECU), Four wheel drive control ECU

-

Buzzer sounds.

U0100

U0129

U0142

U0151

Drive Monitor

(Performs calculations and displays drive monitor information according to the fuel injection volume and pulse count of the vehicle pulse signal.)

  1. Combination meter assembly
  2. ECM, Skid control ECU (brake actuator assembly) or Skid control ECU (master cylinder solenoid), Main body ECU (multiplex network body ECU)

The drive monitor calculations stop and the display is blank.

Nothing

U0100

U0129

U0142

Multi-information Display

(Displays the outside temperature and road surface freezing information.)

  1. Combination meter assembly
  2. Air conditioning amplifier assembly

The multi-information display is blank.

Nothing

-

Dimming Control

(Dims the lighting level of the display or escutcheon key by turning ON and OFF the Dimmer switch.)

  1. Navigation receiver assembly, Radio and display receiver assembly
  2. Main body ECU (multiplex network body ECU)

Control continues.

Nothing

U0140

Destination Auto-detect Function

(Detects the destination of the vehicle based on the package information and switches between those with and without the Entune and HD radio functions.)

  1. Navigation receiver assembly, Radio and display receiver assembly
  2. Main body ECU (multiplex network body ECU)

Control continues.

Nothing

U0140

Steering Wheel Position Detection Function

(Judges the sequence of speaker check in the diagnosis based on information on the steering wheel position.)

  1. Navigation receiver assembly, Radio and display receiver assembly
  2. Main body ECU (multiplex network body ECU)

Control continues.

Nothing

U0140

Trip Counter

(Maintains trip counter information according to the number of times the ignition switch was set to ACC.)

  1. Navigation receiver assembly, Radio and display receiver assembly
  2. Main body ECU (multiplex network body ECU)

Control continues.

Nothing

U0140

Time Counter

(Maintains time count information according to the time elapsed since the ignition switch was set to ACC.)

  1. Navigation receiver assembly, Radio and display receiver assembly
  2. Main body ECU (multiplex network body ECU)

Control continues.

Nothing

U0140

Entry Functions

(Operates the entry lock/unlock, entry trunk open/entry back door unlatch and entry warning/illumination functions.)

  1. Certification ECU (smart key ECU assembly), Main body ECU (multiplex network body ECU)
  2. Main body ECU (multiplex network body ECU), Combination meter assembly

The entry functions do not operate.

Nothing

U0142

Wireless Functions

(Operates the wireless lock/unlock, trunk and panic functions.)

  1. Main body ECU (multiplex network body ECU)
  2. Certification ECU (smart key ECU assembly)

The wireless functions do not operate.

Nothing

U0142

Engine Switch Illumination Control

(Turns the engine switch illumination on/off.)

  1. Certification ECU (smart key ECU assembly)
  2. Main body ECU (multiplex network body ECU)

The engine switch illumination does not operate.

Nothing

U0142

Door Lock (Key-linked Function, Key Lock-in Prevention Function, etc.)

(Performs lock/unlock control.)

  1. Main body ECU (multiplex network body ECU)
  2. ECM

Shift lever-linked auto lock or unlock operation is prohibited.

Nothing

U0100

U0101

  1. Main body ECU (multiplex network body ECU)
  2. Airbag sensor assembly

-

Nothing

U0151

  1. Main body ECU (multiplex network body ECU)
  2. Combination meter assembly

Vehicle speed-linked auto unlock is prohibited.

Nothing

U0155

Wireless/Entry and Start

(Performs wireless/entry and start control.)

  1. Certification ECU (smart key ECU assembly)
  2. Main body ECU (multiplex network body ECU)
  • Entry and start/wireless control does not operate.
  • Door lock or unlock control does not operate.
  • Smart back door opener control does not operate.

Nothing

U0327

Alarm

(Sounds warnings.)

  1. Main body ECU (multiplex network body ECU)
  2. ECM, Power management control ECU

-

Nothing

U0100

U0101

U1133

Lighting Control

(Performs DRL control.)

  1. Main body ECU (multiplex network body ECU)
  2. ECM

DRL control does not operate.

Nothing

U0100

U0101

Display Automatic Dimming

(Controls display dimming control.)

  1. Combination meter assembly
  2. -

Dims the interior display/indicators when not in the tail cancel state.

Nothing

U0155

Illumination

(Performs illumination control.)

  1. Main body ECU (multiplex network body ECU)
  2. Certification ECU (smart key ECU assembly)

Turns off the map light.

Nothing

U0327

Seat Control (Performs memory control [seat position adjustment].)

  1. Main body ECU (multiplex network body ECU)
  2. Front power seat switch LH

-

Nothing

U0208

ADD Switching Limitation

(Prohibits the ADD actuator switching from free to lock when the difference between the vehicle wheel speeds is outside the acceptable range.)

  1. Four wheel drive control ECU
  2. Skid control ECU (master cylinder solenoid)

ADD switching is prohibited.

The 4WD indicator light blinks and the buzzer sounds.

-

Rear Differential Lock Switching Limitation

(Prohibits rear differential lock switching when the vehicle speed is outside the acceptable range.)

  1. Four wheel drive control ECU
  2. Skid control ECU (master cylinder solenoid)

Rear differential lock switching is prohibited.

The 4WD indicator light blinks.

-

Specialized Control during Wheel Speed Failure

(When there is abnormal wheel speed, this control permits switching only when specified conditions are met [not all wheel speeds are abnormal, the brakes are applied, the engine speed is low and all normal wheels speeds are low].)

  1. Four wheel drive control ECU
  2. ECM, Skid control ECU (master cylinder solenoid)

When all 4 wheels are malfunctioning, switching is prohibited.

The 4WD indicator light blinks.

-

4WD Indicator Light and Buzzer Signal Output

(Outputs a signal indicating the indicator and buzzer state, which are used to determine the actuator position and switching status.)

  1. Four wheel drive control ECU
  2. Combination meter assembly

State signal update is not possible.

Nothing

-

4WD State Signal Output

(Outputs a signal when switching to the H4 position is finished.)

  1. Four wheel drive control ECU
  2. Skid control ECU (master cylinder solenoid), Combination meter assembly

State signal update is not possible.

The 4WD indicator light status changes in accordance with changes in the 4WD state signal.

-

L4 State Signal Output

(Outputs a signal when switching to the L4 position is finished.)

  1. Four wheel drive control ECU
  2. Skid control ECU (master cylinder solenoid), Combination meter assembly

State signal update is not possible.

The 4LO indicator light status changes in accordance with changes in the L4 state signal.

-

Rear Differential Lock State Signal Output

(Outputs the rear differential P/S state.)

  1. Four wheel drive control ECU
  2. Combination meter assembly

State signal update is not possible.

The rear differential lock indicator light status changes in accordance with changes in the rear differential lock state signal.

-

Signal Output during Switching

(Outputs the actuator switching state.)

  1. Four wheel drive control ECU
  2. Combination meter assembly

State signal update is not possible.

The indicator lights blink during signal output during switching.

-

Multi-terrain Select Output

(Outputs an multi-terrain select service cancel command signal.)

  1. Four wheel drive control ECU
  2. Drive monitor switch

State signal update is not possible.

Nothing

-

High-Low Switching Limitation

(Prohibits High-Low switching when the vehicle speed or engine speed is outside the acceptable range or the A/T is not in N during the A/T status check.)

  1. Four wheel drive control ECU
  2. ECM, Skid control ECU (master cylinder solenoid)

High-Low switching is prohibited.

The 4WD indicator light blinks and the buzzer sounds.

-

Center Differential Lock Switching Limitation

(Prohibits center differential lock switching when the difference in wheel speeds is large.)

  1. Four wheel drive control ECU
  2. Skid control ECU (master cylinder solenoid)

Prohibits center differential lock switching.

The 4WD indicator light blinks and the buzzer sounds.

-

L4F Switching Limitation

(Prohibits switching to L4F when VSC is malfunctioning.)

  1. Four wheel drive control ECU
  2. Skid control ECU (master cylinder solenoid)

L4F switching is prohibited.

Nothing

-

H-L Actuator Failure Signal Output

(Outputs a signal when the H-L actuator switch is malfunctioning.)

  1. Four wheel drive control ECU
  2. ECM, Skid control ECU (master cylinder solenoid), Combination meter assembly

State signal update is not possible.

The indicator lights blink quickly.

-

Cruise Control Cancel Signal Output

(Outputs a cruise control cancel signal when center differential switching is not completed even though 5 seconds or more have elapsed from the start of switching.)

  1. Four wheel drive control ECU
  2. ECM

State signal update is not possible.

Nothing

-

Center Differential Lock State Signal Output

(Outputs the center differential lock P/S state.)

  1. Four wheel drive control ECU
  2. Combination meter assembly

State signal update is not possible.

The status of the indicator lights changes in accordance with changes in the center differential lock state signal.

-

Push Start (Power Source Switching)

(Changes the power source mode automatically based on the push start switch signal and commands the starter to operate when certain conditions are met.)

  1. Power management control ECU
  2. ECM, Skid control ECU (brake actuator assembly) or Skid control ECU (master cylinder solenoid), Combination meter assembly, Main body ECU (multiplex network body ECU)

Does not display the necessary starting operation commands.

Nothing

U0100

U0129

KDSS System

(Opens and closes the accumulator valve to suppress roll.)

  1. Stabilizer control ECU
  2. ECM, Skid control ECU (master cylinder solenoid), Yaw rate sensor assembly, Steering angle sensor (spiral cable sub-assembly)
  • Control continues.
  • The accumulator valve is open.

Nothing

U0100

U0122

U0124

U0126

Multi-function Switch

(Operates the clearance sonar and 2nd start switch using the steering switch.)

  1. Drive monitor switch
  2. Combination meter assembly

-

Nothing

-

Multi-terrain Select

(Informs the user of the recommended vehicle state according to driving conditions.)

  1. Drive monitor switch
  2. ECM, Skid control ECU (master cylinder solenoid), Combination meter assembly, Four wheel drive control ECU
  • Mode switching is not possible.
  • The display of text messages in the meter display is not possible.

Nothing

-

Crawl Control Switch

(Sends the crawl control switch information.)

  1. Drive monitor switch
  2. Skid control ECU (master cylinder solenoid)

-

Nothing

-

Seat Memory System (Controls the seat position according to the operating conditions.)

  1. Front power seat switch LH
  2. Main body ECU (multiplex network body ECU)

The seat memory system does not operate.

Nothing

-

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