For 1990-2009 cars

The Scan Tool Data Definitions list contains a brief description of all of the engine related parameters that are available on the scan tool. The list is arranged in alphabetical order. A given parameter may appear in any one of the data lists. In some cases the parameter may appear more than once, or in more than one data list in order to group certain related parameters together.

A/C Evap Temperature Sensor: The scan tool displays -39 to 140°C (-38 to 284°F). The voltage applied to the ECM input from the engine coolant temperature sensor is converted to a temperature value.
A/C High Side Pressure Sensor: This parameter displays the voltage from the A/C high side pressure sensor signal circuit to the control module.
A/C High Side Pressure Sensor: This parameter displays the pressure from the A/C high side pressure sensor signal circuit to the control module.
A/C Relay Command: This parameter displays the state of the air conditioning (A/C) clutch relay control circuit as commanded by the control module.
A/C Request: This parameter displays the state of the air conditioning (A/C) request input to the control module from the heating, ventilation, and air conditioning (HVAC) controls.
BARO: This parameter displays the barometric pressure. The control module uses the manifold absolute pressure (MAP) sensor to determine the barometric pressure. The control module uses the barometric pressure for fuel control to compensate for altitude differences.
Desired IAC Position: This parameter displays the desired idle air control (IAC) position as commanded by the control module.
Desired Idle Speed: This parameter displays the desired engine idle speed as commanded by the control module.
DTC Set This Ignition: This parameter displays Yes if a DTC set on the current ignition cycle.
ECT Sensor: This parameter displays the temperature of the engine coolant based on input to the control module from the ECT sensor.
ECT Sensor: This parameter displays the voltage of the engine coolant based on input to the control module from the engine coolant temperature (ECT) sensor.
EC Ignition Relay Command: This parameter displays the state of the control circuit for main relay as commanded by the control module.
EGR Position Sensor: This parameter displays the actual exhaust gas recirculation (EGR) pintle position in volts.
EGR Solenoid Command: This parameter displays the state of the control circuit for EGR solenoid as commanded by the control module.
Engine Load: This parameter displays the calculated engine load in percent based on inputs to the control module from various engine sensors.
Engine Speed: This parameter displays the speed of the engine crankshaft rotation from information received from the crankshaft position (CKP) sensor.
EVAP Purge Solenoid Command (If Equipped): This parameter displays the on-time or duty cycle of the evaporative emission (EVAP) canister purge solenoid commanded by the control module. Zero percent indicates no purge. One hundred percent indicates full purge.
FC Relay 1 Command: This parameter displays the control module commanded state of the fan relay control circuit.
FC Relay 2 Command: This parameter displays the control module commanded state of the fan relay control circuit.
Fuel Gage Command: This parameter displays control module commanded state of the fuel gage control circuit.
Fuel Level Sensor: This parameter displays the voltage signal received by the control module from the fuel level sensor.
Fuel Level Sensor: This parameter displays the percentage signal received by the control module from the fuel level sensor.
Fuel Pump Relay Command: This parameter displays the control modules commanded state of the fuel pump relay control circuit.
HO2S 1 and 2: This parameter displays the voltage output from the H/O2S to the control module. A lower voltage indicates a lean exhaust, while a higher voltage indicates a rich exhaust.
HO2S 1 and 2 Heater Command: This parameter displays the commanded state of the heater control circuit as commanded by the control module.
IAT Sensor: This parameter displays the temperature of the air entering the air induction system based on input to the control module from the intake air temperature (IAT) sensor.
IAT Sensor: This parameter displays the voltage IAT sensor.
Idle Switch (If equipped): This parameter displays if the engine is at idle. The parameter will change from ON to OFF when the engine is not at an idle.
Ignition 1 Signal: This parameter displays a voltage when the control module detects a voltage at the ignition 1 input terminal.
Injector PWM : This parameter displays the average pulse width of the fuel injectors as determined by the control module.
ISC Command (If equipped): This parameter displays the ECM command for the idle speed control (ISC) motor position in percentage. The higher the number, the greater the commanded idle speed reads. The ISC responds to changes in the engine load in order to maintain the desired idle speed.
ISC Motor Position Sensor (if equipped): This parameter displays the actual position for the ISC motor position in percentage. The higher the number, the greater the commanded idle speed reads. The ISC responds to changes in the engine load in order to maintain the desired idle speed.
ISC Motor Position Sensor (if equipped): This parameter displays the actual position for the ISC motor position in voltage.
Knock Sensor: This parameters displays the voltage input to the control module from the knock sensor (KS).
Long Term FT: This parameter displays the commanded Long Term Fuel Trim correction by the control module.
Loop Status: This parameter displays the state of the fuel control system as commanded by the control module. Closed Loop operation indicates that the control module is controlling the fuel delivery based off the oxygen sensor input signal. In Open Loop operation, the control module ignores the oxygen sensor input signal and bases the amount of fuel to be delivered on other sensor inputs.
LT FT Cruise/Accel.: This parameter displays the commanded Long Term Fuel Trim correction by the control module for bank 1 or bank 2 for cruise and acceleration conditions.
LT FT Idle/Decel: This parameter displays the commanded Long Term Fuel Trim correction by the control module for bank 1 or bank 2 for idle and deceleration conditions.
MAP Sensor: This parameter displays the pressure from the MAP sensor to the control module.
MIL Command: This parameter displays the commanded state of the malfunction indicator lamp (MIL) control circuit by the control module.
Octane Level: This parameter displays the octane level in the fuel tank.
Short Term FT Avg.: This parameter displays percentage. This parameter indicates the average of the short term fuel trim cells. The short fuel trim cells are rated, or weighted for the amount of which they are used. For example, the control module rates an idle cell higher than a wide open cell. If a fueling malfunction occurs in the idle cell and the wide open, the idle cell would effect more than the wide open cell. If the oxygen sensor indicates a lean air/fuel mixture, the control module will add fuel increasing the short term fuel trim above 0. If the oxygen sensor indicates a rich air/fuel mixture, the control module will reduce fuel decreasing the short term fuel trim below 0.
Short Term FT Average: This parameter displays percentage. This parameter indicates the average of the short term fuel trim cells. The short fuel trim cells are rated, or weighted for the amount of which they are used. For example, the control module rates an idle cell higher than a wide open cell. If a fueling malfunction occurs in the idle cell and the wide open, the idle cell would effect more than the wide open cell. If the oxygen sensor indicates a lean air/fuel mixture, the control module will add fuel increasing the short term fuel trim above 0. If the oxygen sensor indicates a rich air/fuel mixture, the control module will reduce fuel decreasing the short term fuel trim below 0.
Short Term FT : This parameter displays the short-term correction to the fuel delivery by the control module in response to the oxygen sensor. If the oxygen sensor indicates a lean air/fuel mixture, the control module will add fuel increasing the short term fuel trim above 0. If the oxygen sensor indicates a rich air/fuel mixture, the control module will reduce fuel decreasing the short term fuel trim below 0.
Spark: This parameter displays the amount of spark advance the control module is commanding on the ignition control circuits. The control module determines the desired advance.
TP Sensor: This parameter displays the percent of throttle opening as calculated by the control module using information from the throttle position (TP) sensor.
TP Sensor: This parameter displays the actual voltage on the TP sensor signal circuit as measured by the control module.
Transmission Gear Position Signal: This parameter displays the position of the transmission gear selector that is transmitted over the serial data circuit from the transmission control module (TCM).
Vehicle Security Status (If Equipped): This parameter displays the status of the vehicle theft deterrent system. The normal parameter display for the theft deterrent system is Disabled. If a condition exists with the theft deterrent system the parameter will display Enabled and the vehicle will not start.
Vehicle Speed Sensor: This parameter displays the speed of the vehicle as calculated by the control module from information received from the vehicle speed sensor (VSS).