Patriot 2WD L4-2.4L (2009)
Driver/Vehicle Information Display: Description and Operation
Hill Descent Indicator - Operation
OPERATION
The hill descent indicator automatically gives an indication to the vehicle operator when the Trail Rated Continuously Variable Transmission (CVT) is in
Low or Reverse, the Four Wheel Drive Lock and Off Road modes are activated, and the grade sensing logic of the Controller Antilock Brake (CAB)
senses the vehicle is descending a hill. This indicator is controlled by a transistor on the instrument cluster circuit board based upon cluster programming
and electronic messages received by the cluster from the CAB over the Controller Area Network (CAN) data bus.
The hill descent indicator Light Emitting Diode (LED) is completely controlled by the instrument cluster logic circuit, and that logic will only allow this
indicator to operate when the instrument cluster receives a battery current input on the fused ignition switch output (run-start) circuit. Therefore, the LED
will always be OFF when the ignition switch is in any position except ON or START. The LED only illuminates when it is provided a path to ground by
the instrument cluster transistor. The instrument cluster will turn ON the hill descent indicator for the following reasons:
-
Hill Descent Indicator Lamp-On Message - Each time the cluster receives an electronic hill descent indicator lamp-ON message from the
CAB, the indicator will be illuminated solid. The indicator can be flashed ON and OFF, or illuminated solid, as dictated by the CAB message. A
flashing indicator signifies that the brakes are overheated and that the hill descent feature may not be able to operate as intended. The indicator
remains illuminated until the cluster receives a lamp-OFF message from the CAB, or until the ignition switch is turned to the OFF position,
whichever occurs first.
-
Actuator Test - Each time the cluster is put through the actuator test, the hill descent indicator will be turned ON, then OFF again during the LED
portion of the test to confirm the functionality of the LED and the cluster control circuitry.
The CAB continually monitors inputs from the All-Wheel Drive Control Module (AWDCM) and the ElectroMechanical Instrument Cluster (EMIC)
(also known as the Cab Compartment Node/CCN) to determine the status of the Continuously Variable Transmission (CVT), the 4WD Lock switch, then
monitors its own internal grade sensing logic to determine when the hill descent mode should be engaged. The CAB then sends the proper lamp-ON or
lamp-OFF message to the EMIC.
For proper diagnosis of the AWDCM, the CAB, the EMIC, the CAN data bus or the electronic communication related to hill descent indicator operation
a diagnostic scan tool is required. Refer to the appropriate diagnostic information.
