A technician is diagnosing a powershift transmission that consistently fails to engage third gear, but all other gears engage normally. The machine uses electronically controlled hydraulic valves. What is the most probable cause?

Question: A technician is diagnosing a powershift transmission that consistently fails to engage third gear, but all other gears engage normally. The machine uses electronically controlled hydraulic valves. What is the most probable cause?

Answer options:

• Failed torque converter lock-up clutch ✅ A faulty solenoid valve for the third gear clutch pack
• Low transmission fluid level
• Worn clutch plates in the entire transmission

Correct answer: A faulty solenoid valve for the third gear clutch pack

Explanation: If only one specific gear fails to engage, and the system is electronically controlled, a faulty solenoid valve for that particular clutch pack is the most probable cause, as it directly controls the hydraulic pressure to engage that gear. A failed torque converter lock-up clutch would affect performance across gears, low fluid would affect multiple gears, and widespread worn clutch plates would lead to slipping or failure in multiple gears, not just one isolated gear.