Operation CHARM: Car repair manuals for everyone.
Home >> Ford >> 1997 >> Explorer 2WD V6-245 4.0L VIN X SFI >> Repair and Diagnosis >> Powertrain Management >> Transmission Control Systems >> Description and Operation
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

(Some people have issue connecting. LEMON is investigating. For now, use Firefox or change your DNS server)

Or, hide this message: temporarily or permanently

Transmission Control Systems: Description and Operation












The powertrain control module (PCM) and its input/output network control the following transmission operations:
- Shift timing.
- Line pressure (shift feel).
- Torque converter clutch.

The transmission control is separate from the engine control strategy in the PCM, although some of the input signals are shared. When determining the best operating strategy for transmission operation, the PCM uses input information from certain engine-related and driver-demand related sensors and switches. These include:
- Mass air flow (MAF) sensor.
- Engine coolant temperature (ECT) sensor.
- Intake air temperature (IAT) sensor.
- Air conditioning (A/C) clutch.
- Electronic ignition (EI).
- Throttle position (TP) sensor.
- Programmable speedometer/odometer module (PSOM).
- Bake on/off (BOO) switch.
- Vehicle speed sensor (VSS).

In addition, the PCM receives input signals from certain transmission-related sensors and switches. The PCM also uses these signals when determining transmission operating strategy. The inputs include:
- Transmission fluid temperature (TFT)
- 4x4 low Switch.
- Overdrive drum speed (ODS) sensor sensor.
- Turbine shaft speed (TSS) sensor.
- Output shaft speed (OSS) sensor.
- Transmission control switch (TCS).
- Digital transmission range (DTR) sensor.


Using all of these inputs signals, the PCM can -determine when the time and conditions are right for a shift, or when to apply or release the torque converter clutch. It will also determine the best line pressure needed to optimize shift feel. To accomplish this the PCM uses six output solenoids to control transmission operation. These include:
- Four on/off type shift solenoids (SS1, SS2, SS3, and SS4) to control upshifts and downshifts and the application of the coast clutch.
- One Variable Force Solenoid (VFS) Electronic Pressure Control (EPC) solenoid to adjust transmission line pressure.
- One Pulse-Width Modulated (PWM) Torque Converter Clutch (TCC) solenoid to apply and release the torque converter clutch.


pro multis · About Operation CHARM