GM Service Manual Online
For 1990-2009 cars only
1-2 Shift Time: Displays 0.00-6.38 seconds. This parameter is the actual time of the last 1-2 shift. The shift time is based on the gear ratio change after the commanded 1-2 shift. This value is only accurate if the Adaptable Shift parameter indicates Yes.

1-2 Sol (Solenoid): Displays ON or OFF. These parameters are the commanded status of the 1-2 Shift Solenoid Valves. ON represents a commanded energized state (current is flowing through the solenoid). OFF represents a non-commanded state (current is not flowing through the solenoid).

1-2 Sol. (Solenoid) Open/Shorted to Ground: Displays Yes or No. This parameter indicates if an open or a short to ground exists in the feedback signal from the 1-2 Shift Solenoid Valve to the VCM.

1-2 Sol. (Solenoid) Shorted to Voltage: Displays Yes or No. This parameter indicates if a short to B+ exists in the feedback signal from the 1-2 Shift Solenoid Valve to the VCM.

1-2 TAP Cell (4-16): Scan tool displays kPa or psi. This parameter displays the amount of pressure varied from a calibrated base line pressure for shifts. Each TAP Cell is based on a calibrated shift torque value. Each TAP Cell value is calculated from the last shift time. This cell pressure is used in addition to the calibrated base line pressure to adjust the apply of a clutch or band during the next shift.

2-3 Shift Time: Displays 0.00-6.38 seconds. This parameter is the actual time of the last 2-3 shift. The shift time is based on the gear ratio change after the commanded 2-3 shift. This value is only accurate if the Adaptable Shift parameter indicates Yes.

2-3 Sol. (Solenoid): Displays ON or OFF. These parameters are the commanded status of the 2-3 Shift Solenoid valves. ON represents a commanded energized state (current is flowing through the solenoid). OFF represents a non-commanded state (current is not flowing through the solenoid).

2-3 Sol. (Solenoid) Open/Shorted to Ground: Displays Yes or No. This parameter indicates if an open or a short to ground exists in the feedback signal from the 2-3 Shift Solenoid Valve to the VCM.

2-3 Sol. (Solenoid) Shorted to Voltage: Displays Yes or No. This parameter indicates if a short to B+ exists in the feedback signal from the 2-3 Shift Solenoid Valve to the VCM.

2-3 TAP Cell (4-16): Scan tool displays kPa or psi. This parameter displays the amount of pressure varied from a calibrated base line pressure for shifts. Each TAP Cell is based on a calibrated shift torque value. Each TAP Cell value is calculated from the last shift time. This cell pressure is used in addition to the calibrated base line pressure to adjust the apply of a clutch or band during the next shift.

3-4 Shift Time: Displays 0.00-6.38 seconds. This parameter is the actual time of the last 3-4 shift. The shift time is based on the gear ratio change after the commanded 3-4 shift. This value is only accurate if the Adaptable Shift parameter indicates Yes.

3-4 TAP Cell (4-16): Scan tool displays kPa or psi. This parameter displays the amount of pressure varied from a calibrated base line pressure for shifts. Each TAP Cell is based on a calibrated shift torque value. Each TAP Cell value is calculated from the last shift time. This cell pressure is used in addition to the calibrated base line pressure to adjust the apply of a clutch or band during the next shift.

4WD: Displays Enabled or Disabled. This parameter indicates whether the vehicle is currently in a four-wheel drive mode.

4WD Low: Displays Enabled or Disabled. This parameter is the signal state of the four-wheel drive low circuit. Enabled indicates a 0 voltage signal requesting 4WD Low. Disabled indicates a B+ voltage signal which does not request 4WD Low.

A/C Clutch: Displays ON or OFF. This represents the commanded state of the A/C clutch control relay. The clutch should be engaged whenever ON is displayed. The VCM/PCM will compensate for the additional engine load that is accompanied with the A/C clutch engaged.

Adaptable Shift: The scan tool displays Yes or No. Yes indicates that the proper operating conditions (i.e. TP Sensor Delta, Engine Torque, Vehicle Speed Data, Engine Vacuum, Shift Delay, etc.) were all within the proper operating range during the last shift and the Shift Time was accurate. This shift information is then used through the adaptive function to update the adapt cells. No indicates that not all of the operating conditions were met in order to enable this function and that the adapt cells were not updated.

APP (Accelerator Pedal Position) Angle: Diesel application: Displays a range of 0-100%. The APP angle is computed by the PCM from APP voltage. The APP angle should display 0% at idle and 100% at wide open throttle (WOT).

Cruise: Displays ENABLED or DISABLED. This parameter indicates whether the VCM/PCM is allowing cruise operation. The VCM/PCM has the ability to disable cruise control under certain conditions.

Current Gear: Displays 1, 2, 3, or 4. This parameter indicates the current commanded state of the shift solenoids.

Current TAP (Transmission Adaptive Pressure): Displays a Torque Based Cell range of 0-16. This parameter indicates the current cell used for line pressure modification (adaptation).

ECT (Engine Coolant Temperature): Displays -40°C to 151°C (-40°F to 304°F). This parameter is the input signal of the engine coolant temperature sensor. Engine coolant temperature is high when the signal voltage is low (0 volts), and engine coolant temperature is low when the signal voltage is high (5 volts).

Engine Run Time: Displays a range of 0:00:00-18:12:15 Hr/Min/Sec. This parameter measures how long the engine has been operating. When you turn the ignition switch Off, the value resets to zero.

Engine Speed: Displays 0-8192 RPM. This parameter indicates the rotational speed of the engine expressed as revolutions per minute.

Engine Torque: Displays 0-9999 ft/lb. This parameter is a calculated value based on engine load, throttle position, Mass Air Flow, and other engine and transmission inputs. This parameter is accurate to within 15 ft/lb of actual measured engine torque.

Gear Ratio: Displays a range of 0.00 to 8.00:1. This parameter is the actual gear ratio of the current commanded gear. In the current gear of R, D3, D2, and D1, it is calculated by dividing the input speed by the output speed. In the current gear of D4 with TCC lock up, the gear ratio is calculated by dividing the turbine speed by the output speed.

Hot Mode: Displays ON or OFF. This parameter monitors the transmission fluid temperature. Yes indicates that the transmission fluid temperature has exceeded 135°C (275°F).

Ignition Voltage: Displays 0.0-25.5 volts. This parameter represents the system voltage measured by the VCM/PCM at its ignition feed.

Latest Shift: Displays 0.00-6.38 seconds. This parameter is the actual shift time of the last upshift. This value is only accurate if the Adaptable Shift parameter indicates Yes.

PC (Pressure Control) Sol. Act. (Actual) Current: Displays 0.00-1.1 amps. This parameter is the actual current of the pressure control solenoid circuit at the control module. Zero amp (no current flow) indicates an actual higher line pressure. A reading of 1.1 amp (high current flow) indicates an actual lower line pressure.

PC (Pressure Control) Sol. Duty Cycle: Displays 0%-100%. This parameter is the commanded state of the pressure control solenoid expressed as a percentage of energized ON time. A reading of 0% indicates zero ON time (non energized), or no current flow. Approximately 60% at idle indicates maximum ON time (energized), or high current flow.

PC (Pressure Control) Sol. Ref. (Reference) Current: Displays 0.00-1.1 amps. This parameter is the commanded current of the pressure control solenoid circuit at the control module. Zero amp (no current flow) indicates a commanded higher line pressure. A reading of 1.1 amp (high current flow) indicates a commanded lower line pressure.

Speed Ratio: The scan tool displays a range of 0.00:1-8.00:1. This parameter indicates engine speed divided by transmission output speed.

Standard TAP (Transmission Adaptive Pressure): Displays Yes or No. The standard TAP is an amount of pressure that is added to the base line pressure. If the shift requires standard TAP to achieve the shift, the scan tool displays Yes. If the shift requires more or less than the standard TAP to achieve the shift, the scan tool displays No. This reading indicates that the TAP is out of the standard range.

TCC Brake Switch (PCM Application): Displays Open or Closed. This parameter indicates the state of the TCC brake switch circuit input. Open indicates a zero voltage input (the brake switch is open and the brake pedal is not applied). Closed indicates a B+ voltage input (the brake switch is closed when the brake pedal is applied).

TCC Brake Switch (VCM Application): Displays Open or Closed. This parameter indicates the state of the TCC brake switch circuit input. Open indicates a zero voltage input (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 not applied).

TCC Duty Cycle: Displays 0%-100%. This parameter is the commanded percentage of ON time of the TCC PWM solenoid. 90% represents an ON (energized) commanded state. 0% represents an OFF (non-energized) commanded state.

TCC Duty Cycle Open/Shorted to Ground: Displays Yes or No. This parameter indicates if an open or a short to ground exists in the feedback signal from the TCC PWM Sol. Valve to the VCM.

TCC Duty Shorted to Voltage: Displays Yes or No. This parameter indicates if a short to B+ exists in the feedback signal from the TCC PWM Sol. Valve to the VCM.

TCC (Torque Converter Clutch) Slip Speed: Displays -4080 to +4079 RPM. This parameter is the difference between transmission input speed and engine speed. A negative value indicates that the engine speed is less than the input speed (deceleration). A positive value indicates that the engine speed is greater than the input speed (acceleration). A value of zero indicates that the engine speed is equal to the input speed (TCC is applied).

TFP Switch A/B/C: Displays On/Off, On/Off, On/Off. These parameters are the three inputs from the Automatic Transmission Fluid Pressure Manual Valve Position Switch Assembly. ON represents a 0 voltage signal. OFF represents a B+ voltage signal.

TFT (Transmission Fluid Temperature) Sensor: Displays 0.00-5.00 volts. When the transmission fluid is cold, the sensor resistance is high and the VCM will sense a high signal voltage. As the transmission fluid temperature warms to normal operating temperature, the sensor resistance becomes less and the voltage decreases to about 1.5-2.0 volts.

TP (Throttle Position) Angle: Displays a range of 0%-100%. The TP Angle is computed by the VCM from TP voltage. The TP Angle should display 0% at idle and 100% at Wide Open Throttle (WOT).

TP (Throttle Position) Sensor: Scan tool displays a range of 0.00-5.00 volts. The VCM uses the TP Sensor in order to determine the amount of throttle demanded by the driver. Voltage will be below 1 volt at idle. Voltage will be above 4 volts at Wide Open Throttle (WOT).

Trans. Fluid Temp. (TFT): Displays -40°C to 151°C (-40°F to 304°F). This parameter is the input signal of the transmission fluid temperature sensor. Transmission fluid temperature is high when the signal voltage is low (0 volts), and transmission fluid temperature is low when the signal voltage is high (5 volts).

Transmission ISS (Input Shaft Speed): Displays 0-8192 RPM. This parameter measures the rotational speed of the input shaft expressed as revolutions per minute.

Transmission OSS (Output Shaft Speed): Displays 0-8192 RPM. This parameter indicates the rotational speed of the transmission output shaft expressed as revolutions per minute. On four-wheel drive applications, the transfer case output shaft speed is measured.

Turbine Speed: Displays 0-8192 RPM. This parameter indicates the rotational speed of the Torque Converter Turbine Shaft expressed as revolutions per minute. In commanded gears 1, 2, and 3, the turbine speed equals the input speed. In commanded gear 4, the turbine speed equals 3/4 of the input speed.

Vehicle Speed: Displays 0-255 km/h (0-158 mph). This parameter is the input signal from the OSS sensor.