The P0750 code in your 2017 Toyota Highlander indicates a malfunction with shift solenoid A, and the shuddering you're experiencing is likely related to this solenoid's inability to properly control gear engagement. Your Highlander uses an 8-speed automatic transmission that relies on multiple solenoids for smooth operation.
How Shift Solenoid A Affects Operation
Shift solenoid A controls specific gear applications in the lower gears. When this solenoid malfunctions, the affected gears don't engage properly, causing shuddering as the clutch packs slip and grab. The shudder is most noticeable during shifts that involve solenoid A.
Shudder Characteristics
If the shudder occurs during 1-2 shifts or in first gear, solenoid A is directly implicated. If shudder occurs across all gears, torque converter clutch issues may also be involved. Note when the shudder happens—during acceleration, at specific speeds, or at steady cruise.
Common Causes
The shift solenoid may have failed electrically or mechanically. Contaminated transmission fluid affects solenoid operation. Valve body issues prevent proper fluid routing. Wiring or connector problems affect solenoid control. Low line pressure reduces solenoid effectiveness.
Diagnostic Steps
Using Toyota Techstream, test shift solenoid A function—it should click when commanded. Monitor solenoid resistance and compare to specifications. Check transmission fluid level and condition. Review shift adaptation data. Check for additional transmission codes that might indicate broader issues.