Chapter 4 Answers to Review Questions



Chapter 4 Answers to Review Questions

CLASSROOM MANUAL, PAGES 113-115

SHORT ANSWER ESSAYS

1. Common voltage reference sensors include on/off switches, potentiometers, thermistors, and pressure sensors. Potentiometers, thermistors, and pressure sensors are designed to change their electrical resistance in response to something else changing. Thermistors also change their resistance values in response to conditions. However, they respond to changes in heat. Pressure sensors respond to pressure applied to a movable diaphragm in the switch. As pressure increases, so does the movement of the diaphragm and the amount of resistance in the sensor.

2. The decision to shift or not to shift is based on shift schedules and logic programmed into the memory of the computer. A shift schedule contains the actual shift points to be used by the computer according to the input data it receives from the sensors. Shift schedule logic chooses the proper shift schedule for the current conditions of the transmission.

3. A protection device is placed in an electrical circuit to protect the wires and components from damage due to high current.

4. The computer may receive information from two different sources: directly from a sensor or through a twisted-pair bus circuit, which connects all of the vehicle computer systems. This modulated bi-directional bus system allows the various computers in the vehicle to share information. Multiplexing is a system that allows voltage signals to be shared and to exist on a single wire. The signal has a preset frequency that is accepted only by the intended computer or computers.

5. The solenoids have battery voltage applied to them whenever the ignition is on. The computer completes the ground side of the circuit to activate the solenoids. A solenoid is made of a winding of wire that is wrapped around a movable soft iron core. When current passes through the windings, the resultant magnetic field moves the iron core in or out of the winding. This movement causes the solenoid-controlled valve to open or close.

6. The control unit is programmed to adjust its operating parameters in response to changes within the system, such as component wear. As component wear and shift overlap times increase, the control unit adjusts line pressure by controlling a variable force motor or solenoid to maintain proper shift timing calibrations.

7. Engine speed, throttle position, temperature, engine load, and other typical engine-related inputs are used by the computer to determine the best shift points.

8. Conventional automatic transmissions waste a good amount of the torque produced by the engine through the heat generated by the moving fluid. Also, because gear changes were dependent upon the movement of fluid, up and down shifts were somewhat lazy. Manufacturers could not get the transmissions to respond immediately to the needs of the vehicle without jarring the driver and the vehicle. With the use of electronic controls for transmission operation, the amount of wasted power can be reduced and the overall operation of the transmission can be more responsive with better reliability. Electronic controls also allow for the production of less complicated transmissions, thereby reducing manufacturing and repair costs. The use of electronics eliminates many of the complex circuits and valves in a typical valve body. With this simplicity comes increased reliability, in addition to reduced costs.

9. Honda automatic transmissions are quite unique in the industry because they use constant mesh gears, similar to a manual transmission, to provide for automatic gear changes. When certain combinations of these gears are engaged by clutches, power is transmitted from the main shaft to the countershaft to provide the different gear ranges.

10. The mode switch allows the driver to select a desired shift mode. When the switch is in the Normal position, the transmission automatically shifts gears to achieve maximum fuel economy. Selection of the Power range causes a delay in the shift timing to provide for maximum acceleration.

Fill-in-the-Blanks

1. Constant

2. Voltage drop

3. Voltage generating sensors

4. Parallel circuit

5. Receives, stores, processes, communicates

6. Reference voltage sensors, voltage generators

7. On/off, potentiometers, thermistors, pressure

8. Solenoids, motors, mechanical, hydraulic

9. Two shift

10. Rotational speeds

Multiple Choice

1. C

2. C

3. C

4. B

5. D

6. A

7. A

8. B

9. C

10. D

SHOP MANUAL, PAGES 191-192

ASE-STYLE REVIEW QUESTIONS

1. A

2. B

3. D

4. A

5. A

6. A

7. B

8. C

9. A

10. D

ASE Challenge Questions

1. C

2. C

3. D

4. A

5. B

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