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Chapter 4
Electrical and Electronic Controls
Upon completion and review of this chapter, the student should be able to:
Classroom Manual Objectives

Explain basic electrical terms.

Discuss the basic theories of electricity.

Shop Manual Objectives

Diagnose electronic control systems and
determine needed repairs.
Explain the value of Ohm’s Law.


Explain how laws of magnetism are used
to control automatic transmissions.
Conduct a road test to determine if the
fault is electrical or hydraulic.


Explain what a computer is and how it
works.
Use common electrical test instruments to
locate problems.


Describe the basic types of sensors used
in electronically controlled transmission
systems.
Conduct preliminary checks on EAT
systems and determine needed repairs or
service.

Retrieve trouble codes from common
electronically controlled automatic
transmissions and determine needed
repairs or service.

Follow the prescribed diagnostic
procedures according to DTC and/or
symptom and determine needed repairs or
service.

Perform converter clutch system tests and
determine needed repairs or service.

Inspect, test, and replace
electrical/electronic switches.

Inspect, test, and replace
electrical/electronic sensors.

Inspect, test, bypass, and replace
electrical/electronic solenoids.

Inspect, test, adjust, and/or replace
transmission related electrical/electronic
components.

Explain the advantages of using electronic
controls for transmission shifting.

Explain an elementary shift logic chart.

Briefly describe what determines the shift
characteristics of each selector lever
position.

Explain why adaptive learning is an
important advancement for electronic
control systems.

Identify the input and output devices in a
typical automatic transmission electronic
control system and briefly describe the
function of each.
Overview
This chapter in both manuals reviews basic electrical and electronic theory and testing. They
also cover the ways to test and check electronic transmission control circuits. Because of the
computer controls, it is necessary to understand the operation and the tests that need to be
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made to diagnose problems in them. These chapters also cover the service that can be made.
Explain that most of the transmissions talked about in these chapters are late models.
Reading Assignments
Classroom Manual, pages 83-113
Shop Manual, pages 127-190
Terms to Know
Adaptive learning
ALDL
Ammeter
Amplitude
Computer
Conductor
Current
Cycle
Default mode
Digital signal
Diode
DLC
DMM
DSO
EEPROM
Electricity
Electromagnet
EPC solenoid
Flux lines
Glitches
Impedance
Insulator
LED
Magnetism
Multimeter
Multiplexing
Ohmmeter
Ohm's Law
Open
OSS
Parallel circuit
Potentiometers
Pressure sensors
PWM
Reference voltage
sensors
Resistance
RFI
Scan tool
Semiconductor
Serial data
Series circuit
Shift schedule
Short
Sinusoidal
Solenoid
TCM
Thermistors
VFM
VFS
Voltage
Voltage drop
Voltage generator
Voltmeter
Lecture Outline and Notes
I. Objectives
Review the chapter’s objectives.
II. Basic Electricity
A.
B.
C.
D.
E.
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Describe the factors involved in electrical circuits.
Describe electrical circuit defects.
Define magnetism and its use in automobiles.
Discuss circuit controls.
Explain semiconductors and their automotive use.
Instructor’s Guide to Accompany Today’s Technician: Automatic Transmissions & Transaxles 3E
III. Basic Electrical Testing
A.
B.
C.
D.
Recommend the use of a service manual for proper procedures.
Discuss ammeters, voltmeters, ohmmeters, and multimeters.
Discuss test lights and continuity lights.
Discuss the basic testing of electrical components.
IV. Electrical Problems
A. Describe and discuss the three major types of electrical problems: opens,
shorts, and high-resistance problems. Include in the discussion how each
affects the operation of a circuit.
B. Discuss how the location of these problems can be found using common
electrical test equipment.
V. Lab Scopes
A. Demonstrate how a lab scope works as a visual voltmeter.
B. Discuss the purpose and use of lab scopes.
1. Explain how data is displayed.
2. Describe the scope’s screen layout.
3. Define radio frequency interference (RFI) and glitches.
4. Discuss the effects of RFI and glitches on data displays.
C. Describe the differences between analog and digital scopes.
1. Explain real-time displays.
2. Discuss digital storage oscilloscopes (DSO).
3. Explain the displaying of analog signals.
4. Discuss signal conversion.
D. Various Signals
1. Describe and explain the difference between analog and digital
waveforms.
2. Describe how AC and DC signals are displayed.
VI. Basics of Electronic Controls
A. Discuss the advantages of electronic controls.
1. Explain the impact of shift timing on fuel usage and emissions.
2. Discuss the type of signal generated by the various sensors.
3. Review the shift controls on a non-electronic transmission.
B. Discuss input sensors.
1. Discuss the sensors for engine operating condition and the role they
play in shifting.
2. Describe the gear selector sensor and the impact of its signal on
transmission operation.
3. Discuss the transmission sensors and their role in transmission
operation.
Instructor’s Guide to Accompany Today’s Technician: Automatic Transmissions & Transaxles 3E
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C. Discuss the control modules.
D. Electronically Controlled Transmissions
Describe the basic operation of an EAT.
E. Describe the processing of data to calculate and affect shifting.
VII. Scan Tools
Talk the students through the setup for each of the scan tools that are available.
VIII. General EAT Diagnosis
A. Discuss the general inspection of wiring and control devices.
B. Explain the importance of using service manuals.
1. Discuss paper manuals and their use.
2. Discuss computerized data banks.
C. Explain the use of road tests as important diagnostic tools.
D. Describe the need for good wiring schematics.
E. Explain the necessity for using the proper electrical meter or tester.
F. Preliminary Checks
Discuss the key items that should be checked, such as engine performance,
prior to diagnosing an EAT.
G. Guidelines for Diagnosing EATs
Review the general guidelines and precautions for diagnosing all computer
control systems.
IX. On-Board Diagnostics
A. Basic Diagnostics of Non-OBD II Systems
1. Discuss tools and testers.
2. Discuss and compare domestic controls and DTCs.
3. Discuss import control diagnosis and DTCs.
4. Discuss the tests that should be conducted according to the retrieved
DTCs.
B. Basic Diagnostics of OBD II Systems
1. Discuss tools and testers.
2. Discuss the changes brought about by OBD II.
3. Explain what is signified by the various DTCs and discuss what
actions should be taken in response to them.
X. Electronic Defaults
Discuss the reason for default modes of operation, and describe the problems that
might cause a transmission to go into default.
XI. Detailed Testing of System
A. Discuss general electrical circuit testing.
1. Discuss test equipment and tools.
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Instructor’s Guide to Accompany Today’s Technician: Automatic Transmissions & Transaxles 3E
2. Discuss the importance of performing basic tests first.
3. Explain voltage drops and measurements.
4. Explain the use of scan tools to check transmission controls.
B. DTCs
Describe how to retrieve DTCs from various systems.
XII. Detailed Testing of Inputs
A. Switches
1. Discuss the various switches commonly used today and their purpose.
2. Explain how to test each type of switch.
B. Sensors
1. Discuss the various types of sensors commonly used.
2. Explain how to test each of the various types of sensors. When doing
this, group the sensors by their function, not purpose.
XIII. Detailed Testing of Actuators
A. Explain that most solenoids are electromagnets and can be tested by an
ohmmeter.
B. Discuss the other ways solenoids can be tested.
C. Review the purpose of the various driver circuits.
XIV. Summary
Review the material covered, emphasizing the main points and key words.
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
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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
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Instructor’s Guide to Accompany Today’s Technician: Automatic Transmissions & Transaxles 3E
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
Instructor’s Guide to Accompany Today’s Technician: Automatic Transmissions & Transaxles 3E
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