Raider 2WD V6-3.7L (2008)
Temperature Warning Lamp/Indicator: Description and Operation
ENGINE TEMPERATURE INDICATOR
DESCRIPTION
An engine temperature indicator is standard equipment on all instrument clusters. The engine temperature indicator is located near the upper edge of the
instrument cluster, between the minor gauge set and the speedometer.
The engine temperature indicator consists of a stencil-like cutout of the International Control and Display Symbol icon for Engine Coolant Temperature
in the opaque layer of the instrument cluster overlay. The dark outer layer of the overlay prevents the indicator from being clearly visible when it is not
illuminated. A red Light Emitting Diode (LED) behind the cutout in the opaque layer of the overlay causes the indicator to appear in red through the
translucent outer layer of the overlay when it is illuminated from behind by the LED, which is soldered onto the instrument cluster electronic circuit
board.
The engine temperature indicator is serviced as a unit with the instrument cluster.
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, 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 engine temperature indicator for the following reasons:
-
Bulb Test - Each time the ignition switch is turned to the ON position the engine temperature indicator is illuminated for about two seconds as a
bulb test. The entire bulb test is a function of the PCM.
-
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 will be illuminated 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 will only repeat during the same ignition
cycle if the engine temperature indicator is cycled OFF, then ON again by the appropriate messages from the PCM.
-
Actuator Test - Each time the cluster is put through the actuator 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 ElectroMechanical Instrument Cluster (EMIC) (also known as the Cab Compartment Node/CCN). 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.
For proper diagnosis of the engine coolant temperature sensor, the PCM, the EMIC, the CAN data bus or the electronic communication related to engine
temperature indicator operation a diagnostic scan tool is required. Refer to the appropriate diagnostic information.
