Transmission Control Relay
TRANSMISSION CONTROL RELAYDESCRIPTION
The transmission control relay is located in the Power Distribution Center (PDC) (2) on the left side of the engine compartment between the brake master cylinder (1) and the air cleaner assembly (3).
OPERATION
The relay is supplied fused B+ voltage, energized by the PCM/TCM, and is used to supply power to the solenoid pack when the transmission is in normal operating mode. 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 (ignition key turned to the run position or after cranking engine), the PCM/TCM energizes the relay. Prior to this, the PCM/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 PCM/TCM monitors the terminals to verify that the voltage is greater than 3 volts.