Control Module: Description and Operation

The Transmission Control Unit (TCM) operates the 42RE transmission. The TCM controls the electronic governor, overdrive solenoid, and Torque Convertor Clutch (TCC) solenoid.

Circuit A14 from fuse 3 in the Power Distribution Center (PDC) supplies battery voltage to the Transmission Control Module (TCM). Circuit A5 from fuse 15 in the PDC supplies voltage to circuit A14 through PDC fuse 3.

When the ignition switch is in the START or RUN position, circuit Al from fuse 12 in the PDC connects to circuit A21. Circuit A21 feeds circuit F86 through fuse 6 in the PDC. Circuit F86 connects to the TCM.

The TCM receives the Throttle Position Sensor (TPS) signal on circuit K22. On circuit G7 the TCM receives the vehicle speed sensor signal. The Powertrain Control Module (PCM) supplies 8 volts to the vehicle speed sensor on circuit K25 and 5 volts to the TPS on circuit K6. Circuit K4 from the PCM provides ground for the signals from both sensors.

The TCM provides voltage and ground for the overdrive solenoid, electronic governor, and Torque Converter Clutch (TCC) solenoid. Circuit T20 from the TCM supplies voltage. The TCM provides ground for the overdrive solenoid on circuit T60, the electronic governor on circuit T59 and the TCC solenoid on circuit T22.

On circuit T33, the TCM supplies 5 volts to the transmission temperature sensor, and the governor pressure sensor. The ground path for the sensors is on circuit T35 to the TCM.

Circuits D5 and D82 from the TCM connect to the data link connector. Circuit Z1 provides ground for the data link connector and TCM. Circuit A14 supplies voltage to the connector for the scan tool.