Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Partial Lock-up
As the speed of the vehicle reaches the programmed value, the PCM turns shift solenoid valve DON, and shift solenoid valve D uncovers shift solenoid valve D pressure port (SD) to the lock-up shift valve The lock-up shift valve is moved to the left side which uncovers the torque converter pressure port (91) leading to the right side of the torque converter to engage the torque converter clutch The PCM also actuates A/T clutch pressure control solenoid valve C, and A/T clutch pressure control solenoid valve C pressure (58) is applied to the lock-up control valve and lock-up timing valve When A/T clutch pressure control solenoid valve C pressure (58) is low, torque converter pressure (91) from the lock-up timing valve is low The torque converter clutch is engaged partially A/T clutch pressure control solenoid valve C pressure (58) increases, and the lock-up timing valve is moved to the left side to uncover the port leading torque converter pressure to high Under this condition, the torque converter clutch is engaged by pressure from the right side of the torque converter, this condition is partial lock-up
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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