Ajar Switch

The ajar switch is integrated into their respective latches and hard wired to the BCM. The BCM is responsible for reading the ajar signals at the various Vehicle Access Points (VAP) and broadcasting their status over the vehicle CAN bus. Those signals are:

• Hood Open/Closed
• Left Front Door Open/Closed
• Left Rear Door Open/Closed
• Right Front Door Open/Closed
• Right Rear Door Open/Closed
• Tailgate Open/Closed
• Hard Top On/Off

In order to perform a lock or unlock command, the BCM has to detect if a door, tailgate or hood is open or closed by signal sent to the BCM by the ajar switch. When the ajar switch is open, this indicates that the VAP is physically closed. When the ajar switch reads closed, this means that the VAP is physically open.

The BCM also provides a reference voltage on the hood ajar switch sense circuit. The Hood Ajar Switch switches the hood ajar switch sense circuit to ground when the hood is open. A diagnostic resistor internal to the switch is placed in parallel with the switch.

Since the vehicle can be driven with the doors removed from the vehicle the BCM looks at the voltage of the door ajar switches, There are 2 resistors incorporated into each ajar switch and the return voltages are approximately:

• Door Closed (Switch Open) 8 volts
• Door Open (Switch Closed) 4 volts
• Door Removed 12 volts