Keyless Entry Keypad

The keyless entry keypad is a touch sensitive capacitive sensor. When a finger touches the keypad it changes the capacitance of the sensor in the area of the finger touch. The keypad is then able to determine which area was touched and sends a ground signal to the BCM on the corresponding reference circuit(s). The keypad only works when touched with a finger. The keyless entry keypad may not work when gloves are worn. The gloves act as an insulator and do not allow the finger to change the sensor capacitance.

The BCM monitors for a ground signal on the keyless entry keypad signal input circuits. When an individual keypad button is touched, an individual or combination of the input circuits is routed to ground. The BCM then determines which button was touched based on which circuit(s) are grounded. The keypad has dedicated voltage supply and ground circuits.