RAM 2500 Truck 2WD V8-5.7L VIN D (2004)
Transmission Control System Relay: Description and Operation
45RFE 4 Speed
TRANSMISSION CONTROL RELAY - 45RFE/545RFE Automatic Transmission
DESCRIPTION
NOTE: Due to different power control configurations, the Transmission Control Relay (if equipped) may be referred to as a PCM relay.
The relay is supplied fused B+ voltage, energized by the TCM, and is used to supply power to the solenoid pack when the transmission is in normal
operating mode.
OPERATION
When the relay is "off", no power is supplied to the solenoid pack and the transmission is in "limp-in" mode. After a controller reset, the TCM
energizes the relay. Prior to this, the TCM verifies that the contacts are open by checking for no voltage at the switched battery terminals. After this is
verified, the voltage at the solenoid pack pressure switches is checked. After the relay is energized, the TCM monitors the terminals to verify that the
voltage is greater than 3 volts.
