Durango 2WD V6-3.7L (2009)
Temperature Warning Lamp/Indicator: Description and Operation
Engine Temperature Lamp - Operation
OPERATION
The engine temperature indicator gives an indication to the vehicle operator when the engine temperature gauge reading reflects a condition requiring
immediate attention. 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 Powertrain Control Module (PCM) over the Controller Area Network (CAN) data bus.
The engine temperature 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 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 engine temperature indicator for the following reasons:
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Bulb Test - Each time the ignition switch turns to the on position the engine temperature indicator illuminates for about two seconds as a bulb test.
The entire bulb test is a function of the PCM.
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Engine Temperature High Message - Each time the cluster receives an electronic engine temperature message from the PCM indicating the
temperature is above about 122 °C (252 °F), the engine temperature indicator illuminates and a single chime tone is sounded. The indicator
remains illuminated until the cluster receives a message from the PCM indicating that the temperature is below about 119 °C (246 °F), or until the
ignition switch is turned to the off position, whichever occurs first. The chime tone feature only repeats during the same ignition cycle if the engine
temperature indicator is cycled off, then on again by the appropriate messages from the PCM.
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Self Test - Each time the cluster is put through the self test, the engine temperature indicator will be turned on, then off again during the bulb
check portion of the test to confirm the functionality of the LED and the cluster control circuitry.
The PCM continually monitors the engine coolant temperature sensor to determine the engine operating temperature. The PCM then sends the proper
messages to the instrument cluster, also known as the Cab Compartment Node (CCN). For further diagnosis of the engine temperature indicator or the
instrument cluster circuitry that controls the LED, See: Instrument Cluster / Carrier/Testing and Inspection. If the instrument cluster turns ON the engine
temperature indicator due to a high engine temperature gauge reading, it may indicate that the engine or the engine cooling system requires service.
Use a diagnostic scan tool for proper diagnosis of the engine coolant temperature sensor, the PCM, the CCN, the CAN data bus or the electronic
communication related to engine temperature indicator operation. Refer to the appropriate diagnostic information.
