Scan Tool Data Definitions Part 1
Part 1Engine Scan Tool Data Definitions
Engine Speed: Display shows crankshaft rotation speed in revolutions per minute (RPM) from 0 to 16384.
Desired Idle: Display shows the idle speed that is commanded by the PCM. The PCM will compensate for various engine loads to keep the engine at the desired idle speed from 0 to 2040 RPM.
MAF: Display shows the amount of airflow entering the engine in grams per second (g/s) from 0 to 655. The scan tool will display 0 gms/sec only until 4X reference pulses are received, cranking or running. The PCM updates the MAF sensor display only after 4X reference pulses have been received during an ignition cycle. If during an ignition cycle the vehicle were to stall the MAF display would indicate the last airflow reading obtained while 4X reference pulses were present. If no airflow is monitored by the PCM while the vehicle is running the MAF display will default to 1.2 grams per second.
TP Sensor: Display shows the amount of throttle opening in volts, with closed throttle near 0 volts and wide open throttle above 4.0 volts.
ECT: Display shows the temperature of the engine coolant from -40° to 215°C and -40° to 419°F.
IAT: Display shows the temperature of the intake manifold air from -40° to 215°C and -40° to 419°F.
MAP: Display shows manifold pressure in kilo Pascal (Kpa) from 10 to 105. At key ON engine not running, the MAP value will reflect barometric pressure. To check for an accurate MAP reading multiply your local barometric pressure by 3.386 to obtain a map value that should be within 2 Kpa of displayed value at key ON, engine not running.
BARO: Display shows the BARO in Kpa from 11 to 105. The BARO reading is taken at key ON and is corrected at wide open throttle (WOT). Multiply your local barometric pressure by 3.386 to obtain a BARO value that should be within 2 Kpa of the displayed value.
TPS Normalized: Display shows percent and degrees from 0 to 100 percent and 0.0 to 81.6 degrees. The PCM will compensate for deposits in the throttle body by learning the closed throttle position as zero percent and zero degrees.
Engine Load: Display shows engine load in percent from 0 to 100. Engine load is calculated by the PCM by engine speed and mass airflow. Reading should increase with an increase in RPM and airflow.
IAC Position: Display shows the commanded IAC pintle position in counts from 0 to 1024. The higher the number of counts, the greater the commanded idle speed. Zero is the fully seated position. Idle air control should respond fairly quickly to changes in engine load to maintain desired idle RPM.
Injector. PWM Bank 1: Display shows injector pulse width for cylinders 1, 3, 5, 7 in milliseconds (ms) from 0 to 99.6.
HO2S Bn 1 Sen. 1: Display shows bank 1 sensor 1 HO2S voltage from 0 to 1.16.
Injector. PWM Bank 2: Display shows injector pulse width for cylinders 2, 4, 6, 8 in milliseconds (ms) from 0 to 99.6.
HO2S Bn 2 Sen. 1: Display shows bank 2 sensor 1 HO2S voltage from 0 to 1.16.
Rich to Lean Status Bn 1 Sen 1: Display shows HO2S bank 1 sensor 1 RICH or LEAN which indicates whether oxygen sensor voltage is above, rich, or below, lean, bias voltage. Display should change constantly, indicating that the PCM is controlling bank 1 air/fuel mixture.
Rich to Lean Status Bn 2 Sen I: Display shows HO2S bank 2 sensor 1 RICH or LEAN which indicates whether oxygen sensor voltage is above, rich, or below, lean, bias voltage. Display should change constantly, indicating that the PCM is controlling bank 2 air/fuel mixture.
HO2S Bn 1 Sen. 2: Display shows bank 1 sensor 2 HO2S voltage from 0 to 1.16.
HO2S Bn 1 Sen. 3: Display shows bank 1 sensor 3 HO2S voltage from 0 to 1.16.
Rich to Lean Status Bn 1 Sen 2: Display shows Rich or Lean. This represents the first HO2S in the catalyst monitor. Display should change constantly while in closed loop.
Rich to Lean Status Bn 1 Sen 3: Display shows Rich or Lean. This represents the second HO2S in the catalyst monitor. Display should change much slower when compared to Bank 1 Sensor 2 indicating the catalyst is operating efficiently.
Fuel Trim Cell: Display Shows Fuel Trim Cell range from 0 to 16. Fuel trim cell is dependent upon engine speed and mass air flow readings. A plot of RPM vs. MAF is broken into 16 cells. Fuel trim cell indicates which cell is currently active.
Fuel Trim Learn: Display shows Disabled or Enabled. When conditions are appropriate for enabling long term fuel trim corrections, Fuel Trim Learn will display Enabled. This indicates that the long term fuel trim is responding to the short term fuel trim. If the display shows Disabled then long term fuel trim will not respond to changes in short term fuel trim.
Shrt Term FT Sn 1: Display shows counts from 0 to 255 and percentage from -100% to 99%. The normal position for the short term fuel trim is 128 counts or 0%. A count greater than 128 or a percentage greater than 0% indicates that time is being added to the injector pulse width, increasing the amount of fuel to the engine to compensate for a lean condition sensed by the bank 1 (rear) HO2S. A count less than 128 or less than 0% indicates time is being subtracted from the injector pulse width reducing the amount of fuel to the engine to compensate for a rich condition sensed at the bank 1 (rear) HO2S.
Long Term FT Sn 1: Display shows counts from 0 to 255 and percentage from -100% to 99%. The normal position for the long term fuel trim is 128 counts or 0%. The long term fuel trim is based on short term fuel trim learned values. It is stored in memory blocks of the long term memory according to MAP and RPM values. A count greater than 128 or a percentage greater than 0% indicates that time is being added to the injector pulse width, increasing the amount of fuel to the engine. A count less than 128 or a percentage less than 0% indicates time is being subtracted from the injector pulse width, reducing the amount fuel to the engine.
Shrt Term FT Sn 2: Display shows counts from 0 to 255 and percentage from -100% to 99%. The normal position for the short term fuel trim is 128 counts or 0%. A count greater than 128 or a percentage greater than 0% indicates that time is being added to the injector pulse width, increasing the amount of fuel to the engine to compensate for a lean condition sensed by the bank 1 (rear) HO2S. A count less than 128 or less than 0% indicates time is being subtracted from the injector pulse width reducing the amount of fuel to the engine to compensate for a rich condition sensed at the bank 2 (front) HO2S.
Long Term FT Sn 2: Display shows counts from 0 to 255 and percentage from -100% to 99%. The normal position for the long term fuel trim is 128 counts or 0%. The long term fuel trim is based on short term fuel trim learned values. It is stored in memory blocks of the long term memory according to MAP and RPM values. A count greater than 128 or a percentage greater than 0% indicates that time is being added to the injector pulse width, increasing the amount of fuel to the engine. A count less than 128 or a percentage less than 0% indicates time is being subtracted from the injector pulse width, reducing the amount fuel to the engine.
Loop Status: Display shows OPEN LOOP or CLOSED LOOP. Closed Loop displayed indicates that the PCM is controlling fuel delivery according to oxygen sensor voltage. In Open Loop the PCM ignores the oxygen sensor voltage and bases the amount of fuel to be delivered on other input sensors. Closed Loop operation should begin when the oxygen sensor becomes active, engine coolant temperature exceeds 5°C (41°F) for more than 30 seconds and the PCM has seen a RPM of 1200 or greater for 10 seconds. At extremely high ambient temperatures, or when towing a trailer, it is possible for the system to remain in Open Loop operation to control catalytic converter temperatures.
Engine Run Time: Display shows Hours: minutes: seconds. Engine run time measures how long the engine has been running. When the engine is turned OFF, the timer is reset to zero.
MIL: Display shows ON or OFF. The MIL (Service Engine Soon) is controlled by the PCM and is used to indicate that the PCM has detected a problem that affects vehicle emissions, driveability or could cause powertrain damage.
Ignition 1: Display shows voltage from 0 to 25.5. This represents the system voltage measured by the PCM at its ignition feed.
High Elec Load: Display shows Yes or No. Display should show Yes if several accessories are in operation.
Gen. F Terminal: Display shows Generator F Terminal duty cycle in percent from 0 to 100. The generator is able to produce the desired voltage by varying the duty cycle of the field current. At low engine speeds, the field may have a duty cycle of 90 percent. At higher engine speeds, and lower electrical loads, the duty cycle will be less. The generator produces a PWM signal that is monitored by the PCM.
Knock Retard: Display shows knock retard from 0 to 45 degrees. Which indicates the amount of spark advance in degrees that the PCM is removing from the Ignition Control (IC) in response to the Knock Sensor (KS) signal.
FP Volt Feedback: Display shows feedback of 0 to 25.5 volts. FP volt feedback provides information to the PCM about the fuel pump power supply condition through the fuel pump relay or the oil pressure switch/sensor.
Cam Pulse: Display shows counts from 0 to 255. This parameter is the number of cam signal inputs to the PCM. The counter will reset after 255 counts are reached.
IC Mode: Display shows PCM or ICM. In PCM mode, the PCM controls the ignition timing. The PCM calculates the desired ignition timing based on information the PCM receives from the input sensors. In Ignition Control Module (ICM) mode, the ignition system operates independently from the PCM. The Ignition Control Module maintains a base ignition timing of 10 degrees BTDC and is able to change this ignition timing slightly with increased engine speed. Ignition control mode is in affect whenever an ignition control fault is detected while the engine is running and it will have a noticeable effect on driveability.
Spark: Display shows spark advance in degrees from -90 to 90. The negative number indicates degrees of advance (BTDC). This is a display of the spark advance calculation which the PCM is programming into the ignition system. The PCM computes the desired spark advance using data such as Engine Temperature, RPM, Engine Load, Vehicle Speed and Operating Mode.
Knock Retard: Display shows knock retard from 0 to 45 degrees. Which indicates the amount of spark advance in degrees that the PCM is removing from the Ignition Control (IC) in response to the Knock Sensor (KS) signal.
Knock Counter: Display is shown in counts from 0 to 255. Display shows the number of instances of engine detonation detected by the knock sensor in one-eighth of a second from 1 to 255.
MPH: Display shows vehicle speed in mph and km/h from 0 to 159 mph (0 to 255 km/h). The vehicle speed is converted into mph and km/h for display.
Throttle at Idle: Display shows No or Yes. This display indicates whether the TP Angle being monitored by the PCM is at 0 percent when the throttle is closed.
PNP: Display shows P-N or -R-OD21. P-N displayed indicates the gear select lever is in Park or Neutral. -R-OD21 displayed indicates the gear select lever is in Reverse, Drive, or Low Range.
PSP Switch: Display shows Normal or Hi Press. The PCM compensates engine idle depending on steering load condition. Scan tool will display Hi Press. due to increase of power steering fluid pressure while turning the steering wheel. Scan tool displays Normal under no load condition.
TCC Brake Switch: Display shows Released or Applied. This parameter indicates the state of the TCC brake switch circuit input. Released indicates a B+ voltage input, brake switch closed - brake pedal released. Applied indicates a 0 voltage input brake switch open - brake pedal applied.
Ext Travel Brake: Display shows Released or Applied. This parameter indicates the state of the extended travel brake switch contacts of the torque management brake switch. Scan tool will display Released with the brake pedal released and Applied with the brake pedal applied.
TCC Slip Speed: Display shows TOO Slip Speed in RPM from -4096 to 4064. Display shows the amount of slip between the engine and transaxle input shaft.
Commanded EGR: Display shows commanded EGR position in percent from 0 to 100. Commanded EGR is the EGR pintle position which is being commanded by the PCM which should be very close to the Actual EGR Pos. display.
Actual EGR Pos: Display shows EGR position in percent from 0 to 100. Actual EGR position represents the liner EGR pintle position signal in percent of travel. 0% displayed indicates a closed EGR valve, EGR flow not allowed.
EGR Closed Valve Pintle Position: Display shows position in volts from 0.0 to 5.00. This display represents the voltage that the PCM uses to determine whether or not the EGR valve is fully closed, 0% pintle position.
EGR Pintle Pos: The EGR valve contains a potentiometer type position sensor that provides a voltage proportional to the pintle position. Pintle position is used by the PCM for Closed Loop control of valve pintle position to follow commanded position for diagnostics, and to correct fuel and spark for EGR.
Ignition 0: Displays voltage from 0 to 25.5. This represents the system voltage measured by the PCM at its Ignition 0 feed.
Start Up ECT: Displays start up ECT in °C/°F. This display is the ECT when engine start up occurred.
TP Angle: Display shows throttle angle in percent. Display is computed by the PCM from TP Sensor voltage. Display should read 0% at idle, 100% at Wide Open Throttle (WOT).