This document summarizes the major mechanical and electronic components of an automatic transmission, what each component does, and what to look for to identify issues. The mechanical components include the torque converter, transmission case, front pump, valve body, shift valves like the governor and throttle valve, clutch drums and packs, bands, one-way clutches, planetary gears. The electronic components include solenoids, sensors for output shaft speed, input shaft speed, and brake application status. For each component, the document lists signs of damage or abnormal operation to inspect.

2. Major Components
 Torque Converter
 Hydraulic link between
engine and transmission
 What to look for
 Bluing
 Damaged hub lands
 Stripped converter
studs/nuts
 Leaks

3. Major Components
 Transmission Case
 Houses internal parts
 What to look for
 Cracks
 Stripped threads
 Signs of leaking at
abnormal places (not
seal points, fittings)

4. Major Components
 Front Pump
 Creates hydraulic
pressure for
transmission
 Circulates fluid for
cooling and lubrication
 What to look for
 Damaged pump rotor,
vanes, wear in “pocket”

5. Major Components
 Valve Body
 Directs fluid to
clutches, bands,
converter clutch
 What to look for
 Valve body must be
disassembled to inspect
valves, springs, check
balls
 Load test solenoids

6. Shift Valves
 Governor
 Changes hydraulic
pressure based on
vehicle speed

7. Shift Valves
 Throttle Valve
 Changes hydraulic
pressure based on
load/throttle angle
 Will have a cable
attached to link

8. Major
Components
 Clutch Drum
 Houses Plates
 Clutch Piston
 Uses hydraulic pressure to
apply clutch plates
 Clutch Plates
 Friction
 Steel
 Turning clutch
 Housed inside drum and lets
a component turn
 Holding Clutch
 Splined to case and “holds” a
component

9. Major Components
 Clutch Packs
 Holds or Drives
different components of
planetary gear
 What to look for
 Burnt/Black Frictions or
blued steel
 Bands
 Holds a planetary
component

10. Major Components
Sprag type
One Way Clutch
Roller type
One Way Clutch

11. Major Components
 Planetary Gears
 Provides different gear
ratios
 What to look for
 Teeth chipped
 Play in gears
 Bad thrust washers

12. Electronic Components
EPC Solenoid
 Electronic Pressure Control
 Regulates pressure like
Governor and TV did
 Shift Solenoid
 Supplies ATF to shift valves
for shift control

13. Electronic Components
 OSS
 Output Shaft Speed
Sensor
 Tells PCM drive shaft
speed
 ISS
 Input Shaft Speed
Sensor
 Tells PCM Input speed
 BOO
 Brake On/Off
 Tells ECM if brakes are
applied