Aspen 4WD V8-5.7L Hybrid (2009)
Ready Lamp - Hybrid Drive: Description and Operation
Ready Indicator - Operation
OPERATION
The Hybrid Electric Vehicle (HEV) ready indicator gives an indication to the vehicle operator when the Hybrid Control Processor (HCP) integral to the
Traction Power Inverter Module (TPIM) has determined that the hybrid systems related circuits and components are prepared to move a vehicle that is
stationary. The HEV ready 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 HCP over the Controller Area Network (CAN) data bus.
The HEV ready indicator Light Emitting Diode (LED) is completely controlled by the instrument cluster logic circuit. This logic only allows the
indicator to operate when the instrument cluster receives a battery current input on the fused ignition switch output (run-start) circuit. Therefore, the LED
is 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 turns on the HEV ready indicator for the following reasons:
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Bulb Test - Each time the ignition switch turns to the ON position the indicator illuminates for about four seconds as a bulb test. The entire bulb
test is a function of the HCP.
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HEV Ready Lamp-On Message - Each time the cluster receives an electronic HEV ready lamp-on message from the HCP indicating the HEV
systems are in their ready state, the indicator illuminates. This reading indicates that the ignition switch is in the ON position, the vehicle is
stationary (no vehicle speed input), the transmission gear selector lever is in any position and the HEV system is ready to move the vehicle. The
indicator remains illuminated until the cluster receives a lamp-off message from the HCP, or until the ignition switch is turned to the OFF position,
whichever occurs first.
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Self Test - Each time the cluster is put through the self test, the HEV ready indicator turns on during the bulb check portion of the test to confirm
the functionality of the LED and the cluster control circuitry.
The HCP continually monitors the HEV system circuits, sensors and components to decide whether the system is in good operating condition. The HCP
also monitors a vehicle speed input to determine whether the vehicle is moving or stationary. The HCP then sends the proper lamp-on or lamp-off
message to the instrument cluster, also known as the Cab Compartment Node (CCN). For further diagnosis of the HEV ready indicator or the instrument
cluster circuitry that controls the LED, See: Instrument Panel, Gauges and Warning Indicators/Instrument Cluster / Carrier/Testing and Inspection.
Use a diagnostic scan tool for proper diagnosis of the HEV system, the HCP, the CCN, the CAN data bus or the electronic communication related to
HEV ready indicator operation. Refer to the appropriate diagnostic information.
