A heavy-duty wheel loader equipped with a powershift transmission experiences sluggish forward and reverse engagement, and the machine has reduced power, especially on inclines. The fluid level is correct, and the fluid appears clean. What initial diagnostic step should the technician perform?

Question: A heavy-duty wheel loader equipped with a powershift transmission experiences sluggish forward and reverse engagement, and the machine has reduced power, especially on inclines. The fluid level is correct, and the fluid appears clean. What initial diagnostic step should the technician perform?

Answer options:

• Check transmission control unit (TCU) for fault codes.
• Inspect the transmission cooler for blockages. ✅ Perform a stall speed test.
• Adjust the transmission linkage.

Correct answer: Perform a stall speed test.

Explanation: Sluggish engagement and reduced power, even with correct fluid level and condition, are classic symptoms of torque converter issues, such as a stator free-wheeling improperly. A stall speed test is the most direct way to assess torque converter and engine performance under load and would be the appropriate initial diagnostic step. Checking fault codes or linkage might be subsequent steps, and a cooler blockage typically leads to overheating.