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Home >> Jeep >> 2007 >> Commander Overland, 4WD >> Repair and Diagnosis (Single Page) >> Transmission >> Transmission Control Systems >> 545RFE Automatic Transmission (Service Information) >> 545RFE - Service Information >> Relay-Transmission Control >> Operation >> Transmission Control Relay
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Transmission Control Relay

NOTE: Due to different power control configurations, the Transmission Control Relay (if equipped) may be referred to as a PCM relay.

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.