For 1990-2009 cars

The Transmission and the Engine Scan Tool Data Definitions contains a brief description of all transmission and engine related parameters available on the scan tool. The list is arranged in the alphabetical order.

4WD Low: The scan tool displays Enabled or Disabled. The scan tool will indicate Enabled when the 4WD Low has been selected by the operator.
Brake Switch: The scan displays OPEN/CLOSED. This parameter indicates the state of the brake switch circuit. OPEN indicates a zero voltage in (the brake switch is open and the brake pedal is applied). CLOSED indicates a B+ voltage input (the brake switch is closed and the brake pedal is released).
Current Gear: Displays 1, 2 or 3. This parameter indicates the current command state of the shift solenoid valves.
ECT: The Scan tool range is 80°C-90°C (176F-194°F). The ECT sensor is a thermistor which changes internal resistance as temperature changes. When the sensor is cold (internal resistance high), the PCM monitors a high signal voltage and interprets the voltage as a cold engine. As the sensor warms (internal resistance decreases), the voltage signal decreases and the PCM interprets the lower voltage as a warm engine.
Engine Load: The scan tool range is 10-18%. This parameter indicates engine load based on manifold absolute pressure. The higher the percentage, the more load the engine is under.
Engine Speed: The scan tool range is 0-10,000 RPM. The PCM computes Engine speed from the ignition reference pulses. The Engine speed should remain close to desired idle under various engine loads with the engine idling.
Mode Select Switch: The scan tool displays POWER. When the Mode Select Switch is ON, the POWER parameter indicates if the POWER mode is active. POWER fueling is entered during high engine load operation to provide for maximum engine output.
Monitor Shift Sol. 1: The scan tool displays ON/OFF, when the PCM energizes the shift solenoid 1, line pressure is relieved and the 2-3 shift valve does not operate.
Monitor Shift Sol. 2: The scan tool displays ON/OFF, when the PCM energizes the shift solenoid 2, line pressure is relieved and the 1-2 shift valve does not operate.
Monitor Shift TCC Solenoid: The scan tool displays ON/OFF. This parameter monitors the normally closed TCC release switch. When the TCC release fluid pressure is present, then the switch is open, indicating that the TCC is released. When the fluid pressure is not present, then the switch is closed, indicating that the TCC is applied.
Overdrive Switch: The scan tool displays Overdrive (OD) ON/OFF. When the Overdrive (OD) switch is ON the transmission is in 4th gear. When the Overdrive (OD) switch is OFF the transmission remains in 3rd gear.
Shift Solenoid 1: The scan tool displays ON/OFF. This parameter indicates the status of the 1-2 solenoid valve. When the transmission is in FIRST gear, the scan tool should display ON. When the transmission is in SECOND or THIRD gear, the scan tool should display OFF.
Shift Solenoid 2: The scan tool displays ON/OFF. This parameter indicates the status of the 2-3 solenoid valve. When the transmission is in FIRST gear, the scan tool should display ON. When the transmission is in SECOND or THIRD gear, the scan tool should display OFF.
Spark: The scan tool range -1 to 60 degrees. This displays the PCM controlled value that is being used to control the spark timing.
TCC Solenoid: The scan tool range is 0-100%. This parameter is the commanded percentage of ON time of the TCC solenoid valve. A reading of 100% represents an ON (energized) command state. A reading of 0% represents a non-energized command OFF state.
Throttle Position Level: The scan tool will display 0 level until the throttle is taken off the idle position.
Transmission Range: The scan tool displays Park/Reverse/Neutral/Drive/Drive 2/Low/Invalid. The scan tool displays the decoded position of the transmission range switch (PRNDL). This information is then sent to the Instrument Panel Cluster (IPC) and is displayed to the operator.
Vehicle Speed: The scan tool range is 0-200 km/h/0-125 MPH. This parameter displays the vehicle speed. The Powertrain Control Module (PCM) receives reference pulses from the Vehicle Speed Sensor (VSS) and converts them into km/h and MPH for display.