Active Torque Control 4WD System (Diagnostics - Introduction): Other Toyota RAV4 IV

PRECAUTION

1. IGNITION SWITCH EXPRESSION HINT: The type of ignition switch used on this model differs according to the specifications of the vehicle. The expressions listed in the table below are used this section. Expression Ignition Switch (position) Engine Switch (condition) Ignition Switch off Off Off Ignition Switch ON ON On (IG) Ignition Switch ACC ACC On (ACC) Engine Start START Start
2. TROUBLESHOOTING PRECAUTION NOTE: Since the Active torque control system (4WD control system) may be influenced by a malfunction in other systems, be sure to check for DTCs in the other systems. When removing and installing the 4WD control ECU and each sensor, be sure to check that the normal display is output in test mode inspection and in DTC output inspection after installing all the parts. If the DTC of the CAN communication line is output, repair the malfunction in the communication line and troubleshoot the 4WD control system. Since the CAN communication line has its own length and route, it cannot be repaired temporarily with a bypass wire, etc. When the 4WD control ECU is replaced with a normal one from another vehicle, or the yaw rate sensor is replaced, be sure to perform calibration.

Scheme 87

Scheme 88

Scheme 89

Scheme 90

Scheme 91

Scheme 92

1. GENERAL DESCRIPTION The active torque control 4WD system detects the driving conditions based on signals from each ECU, each switch, the steering angle sensor, the wheel speed sensor, and the yaw rate sensor. The system controls the electronic current passing through the linear solenoid of the electromagnetic coupling, and performs electronic control to distribute the optimum torque to the rear wheels. Main components and their functions. Component Function 4WD Indicator Light Displays warning to driver when system malfunctions Stop Light Switch Detects brake operation Throttle Position Sensor Detects opening angle of throttle Park/Neutral Position Switch Detects "P" position Steering Angle Sensor Detects turning of steering wheel 4WD Linear Solenoid Detects electronic control limiting clutch operation using signals from 4WD control ECU Skid Control ECU with Actuator Detects signals from each sensor and outputs them to 4WD control ECU 4WD Control ECU Detects signals from each sensor via skid control ECU to operate linear solenoid and control system Crankshaft Position Sensor Detects engine rpm and inputs it into ECM Yaw Rate Sensor Detects forward and rearward acceleration of vehicle, and inputs it into skid control ECU Ambient Temperature Detects external ambient temperature and inputs it into body ECU Electromagnetic Coupling Based on amount of current sent from 4WD control ECU, torque is distributed to rear wheels 4WD Lock Switch Change of side auto mode for lock mode 4WD Lock Mode Indicator Light Lock mode control status is communicated to driver through indicator light illumination When lock mode is turned ON, indicator light blinks twice and then remains illuminated. When lock mode is turned OFF, indicator light turns OFF.
2. DRIVING FUNCTION Vehicle Condition Status Control at Vehicle Startup This controls the amount of sideway sliding that occurs at rear of vehicles when accelerating from stop to improve acceleration and hill climbing capacity Slip Control at Vehicle Startup This helps prevent vehicle from sliding sideways. When accelerating a stopped vehicle with the steering wheel turned, it ensures steering stability Slip Control This ensures high turning performance and that stability is not affected by road surface conditions during mid and high speed running Control During Acceleration This controls straight-line running when accelerating during mid and high speeds to ensure straight-line stability of the vehicle
3. REFERENCE MECHANISM Electromagnetic coupling The outer part of the main clutch is attached together with the front housing. The inner part of the main clutch is attached together with the shaft. The control clutch is attached together with the control cam. The activation energy from the transfer is transferred from the propeller shaft to the front housing. However, when the linear solenoid is not operating, the main clutch and control clutch are in a free state, and the activation energy from the transfer is not transferred to the rear wheels. If current is applied to the linear solenoid, the solenoid magnetizes, and the electromagnet pull force causes the armature to attach to the control clutch side. Or, if there is a difference between the rotation speed of the front and rear wheels and the control clutch attaches, a difference occurs in the rotation of the main cam attached to the shaft and the control cam attached to the front housing. As a result, each ball pushes its cam, and the main clutch attaches. The activation energy from the front housing passes through main clutch to the shaft, and then to the rear differential. Then the activation energy is transferred to the rear wheels. Depending on the rotation difference between the front and rear wheels, the system controls the current flowing to the linear solenoid. Then the activation energy applied to the rear wheels is smoothly controlled. Depending on the amount of current, the restraint energy of the outer and inner side of the main clutch changes, and the activation energy from the propeller shaft is smoothly controlled from a limited condition to condition that is nearly a direct-link 4WD condition.

FAIL-SAFE CHART

1. FAIL-SAFE FUNCTION If following malfunctions occur, the 4WD control ECU will stop the function of 4WD control system or partly change the function to control the system. If a malfunction occurs in the sensor signal or actuator, the flow of electricity to the linear solenoid of the electrical coupling is prohibited. As a result, the system enters front wheel drive condition. When a component of the system malfunctions and the fail-safe function activates, the component operation is prohibited. However, if the system is controlling the component and the fail-safe function activates, the system operation is gradually stopped to prevent sudden changes in the vehicle condition. When system control is not possible, the warning light is illuminated to stop operation of the system operation.