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.
Lock up System: Notes
The lock up mechanism of the torque converter clutch operates in the D5 position (2nd, 3rd, 4th, and 5th), in the D4 position (2nd, 3rd, and 4th), and in the D3 position (2nd and 3rd). The pressurized fluid is drained from the back of the torque converter through a fluid passage, causing the torque converter clutch piston to be held against the torque converter cover. As this takes place, the mainshaft rotates at the same speed as the engine crankshaft. Together with the hydraulic control, the PCM optimizes the timing and amount of the lock up mechanism. When torque converter clutch solenoid valve is turned on by the PCM, the torque converter clutch solenoid valve pressure switches the lock up shift valve lock up on and off. The A/T clutch pressure control solenoid valve C, the lock up control valve, and lock up timing valve control the amount of 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.