In Allison ATEC/CEC transmissions, what replaces the modulator valve used in hydraulically controlled transmissions?

In Allison ATEC/CEC transmissions, what replaces the modulator valve used in hydraulically controlled transmissions?

• A. The transmission oil pressure control valve
• B. The throttle position sensor
• C. The transmission temperature sensor
• D. The vehicle speed sensor

Answer: (B)

In Allison ATEC/CEC transmissions, the throttle position sensor replaces the modulator valve. The electronic control uses the throttle position signal to determine engine load, which then guides shift points and the hydraulic pressure applied to the clutches and bands. This replaces the old vacuum-driven modulator that set pressure based on throttle opening. The transmission relies on electronic sensing of load rather than a vacuum modulator to control when to shift and how much pressure to use. Other sensors like temperature, speed, or oil pressure play supporting roles, but they don’t serve as the primary input that replaces the modulator valve.

In Allison ATEC/CEC transmissions, the throttle position sensor replaces the modulator valve. The electronic control uses the throttle position signal to determine engine load, which then guides shift points and the hydraulic pressure applied to the clutches and bands. This replaces the old vacuum-driven modulator that set pressure based on throttle opening. The transmission relies on electronic sensing of load rather than a vacuum modulator to control when to shift and how much pressure to use. Other sensors like temperature, speed, or oil pressure play supporting roles, but they don’t serve as the primary input that replaces the modulator valve.