RAM 1500 Truck 4WD V8-5.9L VIN Z (2002)
Upshift Indicator: Description and Operation
An upshift indicator is standard equipment on all instrument clusters. However, on vehicles not equipped with a manual transmission, this indicator is
electronically disabled. The upshift indicator consists of an upward pointed arrow icon, which appears on the right side of the electronic gear selector
indicator Vacuum Fluorescent Display (VFD) unit. The VFD is part of the cluster electronic circuit board and is visible through a window with a smoked
clear lens located on the lower edge of the speedometer gauge dial face of the cluster overlay. The dark lens over the VFD prevents the indicator from
being clearly visible when it is not illuminated. The icon appears in a blue-green color and at the same lighting level as the odometer/trip odometer
information when it is illuminated by the instrument cluster electronic circuit board. The upshift indicator is serviced as a unit with the instrument cluster.
The upshift indicator gives an indication to the vehicle operator when the manual transmission should be shifted to the next highest gear in order to
achieve the best fuel economy. This indicator is controlled by the instrument cluster circuit board based upon cluster programming and electronic
messages received by the cluster from the Powertrain Control Module (PCM) over the Programmable Communications Interface (PCI) data bus. The
upshift indicator 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 indicator will always be OFF
when the ignition switch is in any position except ON or Start. The indicator only illuminates when it is switched to ground by the instrument cluster
circuitry. The instrument cluster will turn ON the upshift indicator for the following reasons:
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Upshift Lamp-ON Message - Each time the cluster receives an upshift lamp-ON message from the PCM indicating the engine speed and load
conditions are right for a transmission upshift to occur, the upshift indicator is illuminated. The indicator remains illuminated until the cluster
receives an upshift lamp-OFF message from the PCM or until the ignition switch is turned to the OFF position, whichever occurs first. The PCM
will normally send an upshift lamp-OFF message three to five seconds after a lamp-ON message, if an upshift is not performed. The indicator will
then remain OFF until the vehicle stops accelerating and is brought back into the range of indicator operation, or until the transmission is shifted
into another gear.
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Actuator Test - Each time the cluster is put through the actuator test, the upshift indicator will be turned ON, then OFF again during the VFD
portion of the test to confirm the functionality of the VFD and the cluster control circuitry.
The PCM continually monitors the engine speed and load conditions to determine the proper fuel and ignition requirements. The PCM then sends the
proper upshift indicator lamp-ON and lamp-OFF messages to the instrument cluster. For further diagnosis of the upshift indicator or the instrument
cluster circuitry that controls the indicator, (Refer to INSTRUMENT CLUSTER - DIAGNOSIS AND TESTING). For proper diagnosis of the PCM, the
PCI data bus, or the electronic message inputs to the instrument cluster that control the upshift indicator, a DRB III scan tool is required. Refer to the
appropriate diagnostic information.
