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/Transaxle Controls
Automatic Transmission (A/T) models are equipped with an electronic Transmission Control Module (TCM). TCM receives input signals from ECM (RPM signal), idle switch (on-off signal), throttle position sensor (variable signal) and full throttle switch (on-off signal). Based on these values, the TCM calculates optimum timing and duration to energize shift solenoids, overrun clutch solenoid and lock-up solenoid. TCM also indicates when Overdrive (OD) is engaged, by illuminating the OD indicator light.
For more information on TCM, transmission or transaxle controls, refer to appropriate DIAGNOSIS article in AUTOMATIC TRANSMISSIONS.
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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.