ASE A2 Mechanical/Hydraulic Systems Diagnosis

Question 1

A vehicle with an automatic transmission accelerates normally from a stop, but the engine lacks power at highway speeds and the transmission fluid overheats. Which torque converter fault is most likely?

Accepted Answer

Stator one-way clutch seized in the locked position

Answer

A stator that stays locked blocks fluid returning to the pump at coupling speed. This restricts flow, which causes poor top-end performance and overheating.

Question 2

A technician finds automatic transmission fluid in the vacuum hose that runs to the vacuum modulator. What is the most likely cause?

Accepted Answer

A ruptured modulator diaphragm

Answer

A ruptured diaphragm lets fluid pass into the vacuum line and the engine intake. The modulator can then no longer regulate line pressure correctly.

Question 3

Transmission fluid on the dipstick looks milky and pink. What is the most probable cause?

Accepted Answer

A leaking transmission cooler inside the radiator

Answer

Coolant mixing with the fluid gives it a milky pink appearance. The usual entry point is a failed cooler in the radiator tank.

Question 4

A transmission has been overfilled by about a quart. Which symptom is most likely?

Accepted Answer

Foamy, aerated fluid with erratic shifts and fluid expelled from the vent

Answer

Rotating parts churn an overfilled pan and whip air into the fluid. Aerated fluid gives erratic pressure and can foam out of the vent.

Question 5

During a line pressure test, pressure is within specification in Park, Neutral, Drive and the manual ranges, but low only in Reverse. Which is the most likely cause?

Accepted Answer

A leak in the reverse clutch or servo circuit

Answer

Pressure is good in every other range, so the pump, filter and regulator are working. The leak is in a circuit used only in Reverse, such as the reverse clutch seals.

ASE A2 Practice Test

ASE A2 Practice Test

ASE A2 Mechanical/Hydraulic Systems Diagnosis