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.
Transmission Control Module : Design: Lock-Up-Solenoid
The lock-up-solenoid, is located in the gearbox control system, which is mounted on the front edge of the gearbox.
The lock-up-solenoid, consists of an electric coil that controls a hydraulic valve. The solenoid is controlled, like all linear solenoids in the gearbox, by a pulsed current with a frequency of 300Hz and grounded via the Transmission Control Module . The average value on the current signal that deploys the solenoid varies between 0.1 A and 1 A and the demand controls the deployment.
The solenoid controls the torque converter's Lock-up engagement. Engagement occurs by the solenoid pulsing, which gives a smooth engagement of the lock-up function. The solenoid allows the torque converter to work in one of three positions: "Open", "Controlled slipping" and "Locked".
The hydraulic function of the solenoid is linear.
There are diagnostics for the solenoid.
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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.