B3896

CIRCUIT DESCRIPTION
The rear compartment occupant sensor is connected to battery voltage and ground at all times. When a combination of a difference in temperature compared to ambient and movement is detected by the sensor and the ignition is off, the BCM will command the horn to chirp and command the trunk to release within 3 minutes of a detect signal from the sensor. If the ignition is in the on position when the BCM receives the detect signal, the disable switch on the rear compartment occupant sensor will flash. The rear compartment occupant sensor can be disabled by pressing the disable switch on the sensor and holding for two seconds. The BCM will command the trunk ajar telltale on for one minute with each ignition on signal while the sensor is disabled. Once the trunk is opened the sensor will reset to on and resume normal operation. The sensor can also be enabled inside of the trunk with the ignition on or off by pressing the disable switch. The trunk ajar switch signal circuit is used for rear compartment occupant sensor class 2 data.

CONDITIONS FOR SETTING THE DTC
^ The body control module (BCM) detects an open or short to battery positive in the Trunk Ajar Switch Signal circuit.
^ The body control module (BCM) detects a loss of Battery Positive Voltage, Ignition 0 Voltage, or Ground for the Rear Compartment Occupant Sensor.
^ The BCM detects the open or short for more than 2 seconds.

ACTION TAKEN WHEN THE DTC SETS
The service engine soon telltale is illuminated on the instrument cluster.

Diagnostic trouble code B3896 will be stored.

CONDITIONS FOR CLEARING THE DTC
^ An open or short is no longer detected in either the trunk ajar switch signal, battery positive voltage, ignition 0 voltage, or ground circuits.
^ A history DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.
^ A scan tool may be used to clear the DTC.

DIAGNOSTIC AIDS
If the DTC is a history DTC, the fault may be intermittent. Refer to Testing for Intermittent and Poor Connections in Diagrams.

TEST DESCRIPTION

Steps 1-6:

Steps 7-17:

The number(s) below refer to the step number(s) on the diagnostic table.
2. This step will ensure that the DTC is not a history code.
3. Tests for the proper operation of the circuit in the high voltage range.
4. Tests for the proper operation of the circuit in the low voltage range. If the fuse in the jumper wire opens when you perform this test, the signal circuit is shorted to voltage.