Grand Caravan V6-3.8L VIN L (2007)
Transmission Control System Relay: Description and Operation
40TE Automatic Transaxle
Description
DESCRIPTION
The transmission control relay (Figure 1) is located in the Intelligent Power Module (IPM), which is located on the left side of the engine compartment
between the battery and left fender.
Figure 1 Transmission Control Relay Location
Operation
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.
