Dakota 2WD V6-3.9L VIN X (1997)
Temperature Warning Lamp/Indicator: Description and Operation
SYSTEM OPERATION
The transmission oil temperature warning lamp gives an indication when the Powertrain Control Module (PCM) has detected that the automatic
transmission oil is overheated. One side of the lamp bulb receives battery voltage when the ignition switch is turned to the On position. The lamp
ground is controlled by the instrument cluster circuitry based upon messages received from the PCM on the Chrysler Collision Detection (CCD)
data bus. The PCM sends a lamp-on message for about two seconds when the ignition switch is turned to the On position as a bulb test.
Following the bulb test, the PCM uses an input from the automatic transmission oil temperature sensor located within the transmission, along with
its internal programming, to decide whether a condition exists that requires the transmission oil temperature warning lamp to be turned on. The
PCM then sends the proper message to the instrument cluster on the CCD data bus to turn the lamp on or off.
CIRCUIT OPERATION
The transmission temperature lamp is used to alert the operator that the transmission oil temperature has exceeded a pre-determined level. Circuit
T34 provides the input to the Powertrain Control Module (PCM).
When the PCM determines the need for lamp illumination it sends a message over the CCD bus to the Body Control Module (BCM). The BCM
processes this message and sends a message to the instrument cluster via the CCD bus for lamp illumination.
