1.Air mix servomotor
(1)Construction
The air mix servomotor consists of the motor, limiter, potentiometer and moving contact, etc., as shown in the figure and it is activated by the signal from the ECU.
(2)Operation
When the air mix damper is shifted to HOT, the MH terminal will be the power source and the MC terminal will be the ground to rotate the servomotor to make the shift. When the MC terminal becomes the power source and the MH terminal becomes the ground, the servomotor rotates in the opposite direction to shift the air mix damper to COOL.
The moving contact of the potentiometer moves in synchronicity with the servomotor revolving, generates electric signals according to the damper position, and feeds back the actual damper position to the ECU. When the damper comes to the desired position, the air mix servomotor stops the current to the servomotor.
The air mix servomotor is equipped with a limiter that shuts off the current to the motor when full-stroke movement is activated. When the moving contact that synchronizes with the servomotor revolving reaches the full-stroke positions, the circuit is open to stop the motor.
2.Air inlet servomotor
(1)Construction
The air inlet servomotor consists of the motor, gear, moving plate, etc., as shown in the figure.
(2)Operation
Pressing the air inlet control switch will generate the ground circuit for the servomotor to allow the current to the motor and moves the air inlet damper.
When the damper is changed to FRESH or RECIRC position, the contact of the moving plate linked with the motor is released and the circuit is open to stop the motor.
3.Airflow servomotor
(1)Construction
The airflow servomotor consists of the motor, moving contact, circuit plate, motor drive circuit, etc., as shown in the figure.
(2)Operation
When the airflow control switch is operated, the motor drive circuit determines whether the damper position changes to the right or left side and directs the flow of current to the motor to shift the moving contact linked to the motor.
When the moving contact moves to the position according to the airflow control switch position, the contact with the circuit plate is released, the circuit is open and the motor stops.
When the airflow control switch is moved from FACE to DEF
Input A will be 1 because the circuit is open, and input B will be 0 because the grounded circuit is generated. As a result, output D will be 1 and output C will be 0 and allow the current for the motor from D to C. After the motor revolves and moving contact B releases contact with DEF, input B will be 1 because the circuit will be opened. As a result, both output C and D will be 0, the current to the motor is cut and the motor stops.
Some models do not have a contact in the servomotor.
A/C control ECU rotates the motor based on the operation of the selector on the control panel.
Damper position is monitored in reference to the potentiometer voltage that varies according to the motor.

1.Interior temperature sensor
(1)Construction
The interior temperature sensor uses the thermistor and is installed in the instrument panel with the aspirator. The aspirator utilizes the air blown from the blower to suck the air inside the vehicle in order to detect the average interior temperature.
(2)Function
It detects the interior temperature that is used as the basis for the temperature control.
2.Ambient temperature sensor
(1)Construction
The ambient temperature sensor uses the thermistor and is installed at the front of the condenser. It detects the exterior temperature.
(2)Function
It detects the exterior temperature that is used for controlling the fluctuation of the interior temperature caused by the exterior temperature fluctuation.
3.Solar sensor
(1)Construction
The solar sensor uses a photodiode and is installed in the upper portion of the instrument panel. It detects the amount of sunlight.
(2)Function
It detects the amount of sunlight that is used for controlling the fluctuation of the interior temperature caused by the amount of sunlight fluctuation.
4.Evaporator temperature sensor
(1)Construction
The evaporator temperature sensor uses the thermistor and is installed on the evaporator. It detects the temperature of the air passing through the evaporator (surface temperature of the evaporator).
(2)Function
It is used for frost prevention, temperature and time-lag airflow control.
5.Water temperature sensor
(1)Construction
The water temperature sensor uses the thermistor. It detects the coolant temperature based on the engine water temperature sensor. The signal is transmitted from the engine ECU.
In some models, the water temperature sensor is installed at the heater core.
(2)Function
It is used for temperature control, warm-up control, etc.
Some vehicles are equipped with the following sensors.
Duct sensors
The duct sensors use the thermistor and are installed at inside of the side register. It detects the temperature of the air blown toward the side register and precisely controls the air temperature of the individual airflow.
Smog ventilation sensor
The smog ventilation sensor is installed in the front portion of the vehicle and detects the level of CO (carbon monoxide), HC (hydrocarbons), and NOx (oxides of nitrogen) to control switching between FRESH and RECIRC.

Outline

1.    Auto A/C (Air Conditioner) System
The auto A/C system is activated by setting the desired temperature with the temperature selector and pressing the AUTO switch. The system immediately adjusts and maintains the temperature at the set level with the automatic control of the ECU.

Location
The auto A/C is controlled by the following components:
1.A/C control ECU (or A/C amplifier)
2.Engine ECU
3.Control panel
4.Interior temperature sensor
5.Ambient temperature sensor
6.Solar sensor
7.Evaporator temperature sensor
8.Water temperature sensor (engine ECU sends the signal)
9.A/C pressure switch
10.Air mix servomotor
11.Air inlet servomotor
12.Airflow servomotor
13.Blower motor
14.Blower controller (controls blower motor)
In some models, the following components are also used for the auto A/C control.
Duct sensors
Smog ventilation sensor

ECU

1.A/C control ECU
The ECU computes the temperature and volume of the air to be blown and determines which vents to use based on the temperature detected by each sensor and the set temperature.
These values are used to control the air mix damper position, blower motor speed, and airflow damper positions.
In some models, MPX (multiplex communication system) is used to transmit operation signals from the control panel to the A/C control ECU.

When the automatic light control sensor detects level of the ambient light while the light control switch is in the AUTO position (or in the OFF position for the models without the AUTO position), it transmits a signal to the light control unit, which turns on the taillights and then the headlights depending on the ambient brightness.
The system also has a function that turns on the taillights but prevents the headlights from turning on briefly in cases where it becomes dark for a moment, such as when driving under a bridge or down a tree-lined street when ambient are bright. However, if after a certain lag time has elapsed, the ambient brightness is lower than a specified value, the headlights will come on.
There are various types depending on the model, such as a type in which the automatic light control sensor and light control unit are one unit or a type in which the taillights and headlights come on at the same time.

When the automatic light control sensor detects level to the ambient light, it outputs a pulse signal to terminal A of the light control unit. When the light control unit judges the decrease in ambient brightness, and activates the taillight and headlight relays to turn on the taillight and headlight.
When the light control unit judges an increase in ambient brightness, the taillights and headlights go off.

When the automatic light control sensor detects level of the ambient light while the light control switch is in the AUTO position (or in the OFF position for the models without the AUTO position), it transmits a signal to the light control unit, which turns on the taillights and then the headlights depending on the ambient brightness.

The system also has a function that turns on the taillights but prevents the headlights from turning on briefly in cases where it becomes dark for a moment, such as when driving under a bridge or down a tree-lined street when ambient are bright. However, if after a certain lag time has elapsed, the ambient brightness is lower than a specified value, the headlights will come on.

There are various types depending on the model, such as a type in which the automatic light control sensor and light control unit are one unit or a type in which the taillights and headlights come on at the same time.

When the automatic light control sensor detects level to the ambient light, it outputs a pulse signal to terminal A of the light control unit. When the light control unit judges the decrease in ambient brightness, and activates the taillight and headlight relays to turn on the taillight and headlight.
When the light control unit judges an increase in ambient brightness, the taillights and headlights go off.

Malfunction areas in Turbocharger/ Supercharger
Due to insufficient boost pressure, insufficient power is felt when vehicle starts or a heavy load is applied.
When sudden accelerating without load, diesel smoke level inspection is normal (diesel engine) Intake system
Malfunction areas in  Intake system
When a heavy load is applied and the engine speed is high, there is a shortage of intake air and insufficient power is felt.
Feeling that engine speed has hit its peak, however engine speed does not increase.
When sudden accelerating without load, a lot of black smoke is exhausted in the diesel smoke level inspection (diesel engine)

Malfunction areas in  EGR system

Due to excessive EGR volume, insufficient power is felt when vehicle starts or a heavy load is applied.
When sudden accelerating without a load, more black smoke is exhausted in the diesel smoke level inspection (diesel engine)
Malfunction areas in  Exhaust system
Due to clogging in exhaust system, there is a shortage of intake air, and insufficient power is felt when a heavy load is applied and there the engine speed is high.
When driving with the throttle valve fully open in 1st or 2nd gear, the maximum speed is lower.

Malfunction areas in  Cooling system

After driving for a while with a heavy load applied and engine speed high, insufficient power is felt.
The water temperature indicator indicates high temperature. Knocking is often accompanied.
In the case of diesel engine, even if overheat occurs, insufficient power is not immediately felt. Until when a malfunction in the cylinder head gasket,
piston, etc. occurs, insufficient power is not felt, so it is necessary to pay attention (diesel engine).

Malfunction areas in  Fuel system

Due to fuel supply shortage, insufficient power is felt when a heavy load is applied or the engine speed is high.
When driving with the throttle valve fully open in 1st or 2nd gear, the maximum speed is lower.
Engine stall also may occur.

Malfunction areas in  Injection timing

If injection timing advances, insufficient power is felt when vehicle starts or a heavy load is applied and diesel knocking sound is loud (diesel engine).
When sudden accelerating without a load, black smoke volume is large in the diesel smoke level inspection (diesel engine)

Malfunction areas in  Injection volume

Due to injection volume shortage, insufficient power is felt in the heavy load range, from low speed to high speed (diesel engine).
When sudden accelerating without a load, diesel smoke level inspection is small (diesel engine)
Due to injection volume shortage, insufficient power is felt in the heavy load range, from low speed to high speed (diesel engine).
When sudden accelerating without a load, diesel smoke level inspection is small (diesel engine)

Malfunction areas in  Compression pressure

Insufficient power is felt in all ranges from the starting acceleration.

Malfunction areas in  Automatic transmission

Due to clutch or brake slip, vehicle speed does not follow the engine speed increase.
The symptom significantly appears when running with half throttle.
Due to shifting point failure, both engine speed increase and vehicle speed increase is retard.
Due to the lock up clutch full-time operation, both engine speed increase and vehicle speed increase is retarded

Engine System
• When fully depressing the accelerator pedal, whether the throttle valve fully opens or not
• Whether the amount of coolant and engine oil is good or not, whether the drive belt tension is good or not (overheat is suspected)
• Whether rough idling exists or not (compression pressure drop in a specific cylinder is suspected)
• Whether the air cleaner element has dirt or not (clog in intake system is suspected)
• Whether the diesel smoke level when sudden accelerating without load is good or not (diesel engine only)
• Whether no load maximum speed is good or not (diesel engine only)

Drive train System
• Whether the clutch slip exists or not
• The amount of ATF is good or not (AT slip is suspected)
• Whether stall speed is good or not (AT slip and torque converter failure are suspected)
Brake System
• Whether the brake drag exists or not
Others System
• Whether the fuel sedimenter indicator operates or not

The symptoms relating to strong shocks in the driving system in an A/T vehicle can roughly be separated into two types.
• Only shock is sensed
• Both shock and sound are sensed When both shock and sound are sensed, even if the shock itself is not strong, since the sounds which is sensed by the ears and the shock which is sensed by the body are synchronized, the degree of complaint tends to be large. The conditions in which a strong shock occurs varies depending on the causes, such as starting, shifting, accelerating, sudden throttle opening and closing, etc. When proceeding with troubleshooting for strong shock in an A/T vehicle, it is necessary to pay attention to the following.
• It is important to judge whether the shock is malfunction level or not, because a certain shock is not avoidable when shifting due to the construction and function of A/T vehicle. To be able to judge accurately, it is important to drive an A/T vehicle on a daily basis in order to become familiar with the level in each model, so as to develop a good sense of judgement regarding whether it is a malfunction or not.
• As for the cause of the strong shock, the malfunction area can be signifi cantly narrowed down based on the malfunction occurrence conditions. A cause other than an A/T can also be considered, so it is important to understand the occurrence conditions and problem symptoms accurately. When using an unspecifi ed ATF, it negatively affects the shock when the clutch engages or slips, so it is important to use the specifi ed one. As the coeffi cient of friction becomes larger, the greater the shift shock will be.
1. Basic inspection
Inspection methods
Perform “Basic Inspection” in the Repair Manual.
2. Conformity with the result of the DTC output (ECT)
Even if the DTC indicates abnormality, the malfunction that the DTC indicates is different from the malfunction that the customer points out. Therefore, inspect the relationship between the DTC and the problem symptom.
Normal DTC is displayed
The cause of the malfunction can be estimated in the area that has no DTC.
DTC is displayed
Check the conformity between the output result of the DTC and the problem symptom.
No DTC is displayed
When no DTC is displayed, the ECU itself can be considered not to operate properly. Therefore, the malfunction can be judged to be in the power source or the relevant area.
• DTC and problem symptoms When DTC is detected, the code may be related to the shock reducing control. But, the contents greatly affect the engine or ECT control, other symptom problems may be accompanied by the malfunction. For example, when IDL contact is always OFF, the malfunction of the engine hunting or idling speed failure is more signifi cant than that of the shock when shifted from N to D position. In the DTC that is related to ECT relevant area, if the S1 or S2 solenoid valve relevant area DTC is output, the symptom may rather be felt shifting point failure or insuffi cient power than the strong shock.
3. Narrow down whether A/T or others according to road test
Hold the gear in position, so as not to shift it, and verify whether the shock occurs or not when accelerating and decelerating. Narrow down whether the malfunction cause is in the A/T itself or in other areas. If the shock occurs under this condition, the cause can be judged to be in the driving train and suspension devices, that is not in the A/T. In this case, gear noise may be accompanied by shock.
Causes other than A/T
Drive train and suspension failures
• Engine mount failure
• Rattle and play of propeller shaft and drive shaft are large
• Backlash in the differential is large
• Suspension installation condition is bad
etc.
4. Narrow down by occurrence condition and inspection result
The occurrence of a strong shock caused by the A/T itself, happens only when shifting. Therefore, based on the shock occurrence conditions, considering what the acting elements are or what commonly occurs can narrow down the cause.
Strong shock when both the shift lever is moved and the gear is changed
It is considered that the cause is not in each acting element but in the line pressure, which in relation to all the acting elements, is excessively high.
If this occurrence timing is same as the ATF changed timing, wrong ATF may be used.
Line pressure adjustment
Line pressure changes depending on the number of the throttle valve E ring.
Adding one E ring reduces approximately 0.2 kg/cm².
Strong shock only when the gear is changed
• When a strong shock occurs when all the gears are change
Since the gear is changed when the shifting point is high and the engine speed is rather high, the shock becomes strong. In vehicles other than ECT ones, an extremely low governor pressure is considered to a cause. In an ECT vehicle, vehicle speed affecting the shifting point control and an throttle position signal are considered to be causes. When a vehicle speed lower than that of the actual speed is input or a greater throttle signal than that of the actual throttle opening is input, the shifting point will be higher. Both vehicle speed signals and throttle signals are DTC items, but in the DTC detection level malfunction, a strong shock will not occur. Example: When an abnormal code regarding the vehicle speed signal is detected; because there are two sensors When an abnormal code regarding the throttle signal is detected; the shifting point will be conversely low, because the throttle opening is activated to 0 degrees in response to the fail safe function. The malfunction in the vehicle speed signal may affect other systems (engine, TRC, ABS, etc.), so check it.
• Strong shock when gear is changed only to a specifi c gear position
When gear is changed to the gear, the cause will be considered to be in the acting element.
Strong shock only when the shift lever is shifted from N to D or from N to R
The malfunction is considered to be in the acting element related to D or R. The malfunction area is judged to be in the acting element which is not commonly used.
(1) Only when shift lever is shifted from N to D
• Accumulators and servos in C1
• Scot control system, STP signal is not input, NSW signal is not input (ECT vehicle only)
(2) Only when shift lever is shifted from N to R
• Accumulators and servos in C2
• Accumulators and servos in B3

With automatic transaxle/transmission vehicles, the driver does not need to judge when shifting up and down. The gears are shifted automatically according to the vehicle speed and the amount that the accelerator pedal is depressed. A unit in which automatic gear shifting is controlled by an ECU (Electronic Control Unit) is called an ECT (Electronically- Controlled Transaxle/transmission) and a unit that does not use an ECU is called a full hydraulically-controlled automatic transaxle.

Currently, almost all vehicles use ECTs. In some models, the gear shifting pattern can be selected according to the driver’s preference and road conditions. This provides improved fuel economy and driving performance.

Types of Automatic Transaxle

Automatic transaxles can be basically divided into two types, those used in FF (Front-engine, Front wheel-drive) vehicles and those used in FR (Frontengine, Rear-wheel-drive) vehicles. Transaxles for FF vehicles have an internal final drive unit, but those for FR vehicles have a final drive unit (differential) mounted externally. The type of automatic transaxle used with FR vehicles is

called a transmission.

In the transversely-mounted automatic transaxle, the transmission and the final drive unit are housed integrally in the same case. The final drive unit consists of a pair of reduction gears (the drive and driven gears), and differential gears.

ECT (Electronically Controlled Transaxle)

An ECT (Electronically Controlled Transaxle) consists of following components:

1. Torque converter

Transmitting and multiplying the torque generated by the engine.

2. Planetary gear unit

Shifting such as deceleration,reverse, acceleration, and neutral.

3. Hydraulic control unit

Controlling the hydraulic pressure so that the torque converter and planetary gear unit operate smoothly.

4. Engine & ECT ECU

Controlling the solenoid valves and the hydraulic control unit to provide the optimum driving condition. It uses hydraulic pressure to automatically shift gears in accordance with ECU

control signals. The ECU controls the solenoid valves according to the condition of the engine and vehicle detected by the sensors, thus controlling the hydraulic pressure.

Full Hydraulically-controlled Automatic Transaxle

The construction of the full hydraulicallycontrolled automatic transaxle is basically the same as the ECT. However, this transaxle mechanically controls shifting by detecting the vehicle speed hydraulically from the governor valve and detecting the accelerator opening from the throttle valve via the amount of movement of the throttle cable.