NAPA Automatic Transmission Systems 2 — Questions and Answers
Question 1: Which valve in the valve body primarily regulates main line pressure from the pump?
- Manual valve
- Pressure regulator valve (Correct answer)
- 1-2 shift valve
- Accumulator valve
Correct answer: Pressure regulator valve
The pressure regulator valve balances pump output against spring force to set line pressure.
Question 2: What is the main purpose of an accumulator in an automatic transmission hydraulic circuit?
- Store fluid for cold starts
- Raise line pressure at wide-open throttle
- Cushion clutch or band apply for smoother shifts (Correct answer)
- Cool fluid before it returns to the pan
Correct answer: Cushion clutch or band apply for smoother shifts
An accumulator absorbs part of the apply pressure briefly so the clutch or band engages gradually.
Question 3: The manual valve in the valve body is positioned by which component?
- The gear selector linkage or cable (Correct answer)
- The governor
- The throttle valve cable
- The torque converter clutch solenoid
Correct answer: The gear selector linkage or cable
The driver's shift lever moves the manual valve through linkage to route fluid for the selected range.
Question 4: On a hydraulically controlled transmission, a throttle valve (TV) cable adjusted too loose will most likely cause what?
- Harsh, delayed upshifts
- No reverse engagement
- Torque converter shudder
- Early, soft upshifts (Correct answer)
Correct answer: Early, soft upshifts
Low TV pressure reduces both line pressure and shift delay, causing early, mushy shifts that can lead to slipping.
Question 5: In a transmission with a mechanical governor, governor pressure changes in direct relation to what?
- Engine load
- Vehicle (output shaft) speed (Correct answer)
- Fluid temperature
- Engine vacuum
Correct answer: Vehicle (output shaft) speed
The governor is driven by the output shaft, so its pressure rises as road speed increases.
Question 6: After a valve body overhaul, the vehicle has erratic and harsh shifts. Which reassembly error is a common cause?
- Overtightened pan bolts
- Wrong dipstick tube seal
- Missing or misplaced check ball (Correct answer)
- Incorrect filter gasket color
Correct answer: Missing or misplaced check ball
Check balls control flow direction and timing, so a missing or misplaced one changes apply rates and shift quality.
Question 7: A pressure test shows low line pressure in every gear range. What is the most likely cause?
- Clogged filter or worn pump (Correct answer)
- Leaking reverse servo seal
- Faulty governor
- Sticking 2-3 shift valve
Correct answer: Clogged filter or worn pump
Low pressure in all ranges points to something common to all circuits, such as the pump supply or filter.