Scan Tool Data Definitions

Scan Tool Data Definitions

A list of each data message displayed on the scan tool will be explained in Engine Controls. This information will assist in emission or driveability problems. The displays can be viewed while the vehicle is being driven. Always perform the Diagnostic System Check Engine Controls first. The Diagnostic System Check will confirm proper system operation.

5 Volt Reference 1
This parameter displays the voltage level of 5 volts reference 1 circuit to the various sensor's power supplies.

5 Volt Reference 2
This parameter displays the voltage level of 5 volts reference 2 circuit to the various sensor's power supplies.

5 Volt Reference 3
This parameter displays the voltage level of 5 volts reference 3 circuit to the various sensor's power supplies.

A/C Request Signal
This parameter displays the state of the air conditioning (A/C) request input to the ECM from the heating, ventilation, and air conditioning (HVAC) controls.The scan tool will display Yes or No. Yes indicates the ECM is receiving a request from the HVAC system to ground the A/C clutch relay control circuit, engaging the A/C compressor clutch. No indicates the ECM is not receiving a request from the HVAC system to ground the A/C clutch relay control circuit.

Actual FRP Regulator
This parameter displays the fuel rail pressure (FRP) regulator control feedback current as calculated by the ECM. This can be compared to the Desired FRP Regulator to determine FRP regulator accuracy or fuel supply pump problems.

Actual Fuel Rail Pressure
This parameter displays the fuel rail pressure as calculated by the ECM using the signal from the fuel rail pressure (FRP) sensor. The actual fuel rail pressure is a range of values indicating a low pressure when the fuel rail pressure is low to a high pressure when the fuel rail pressure is high. This value is listed in psi or MPa. Note that this parameter will only update with the engine running or one time after the key is cycled when the ignition has been turned OFF for longer than 10 seconds.

APP Indicated Angle
This parameter displays the angle of the accelerator pedal as calculated by the ECM using the signals from the accelerator pedal position sensors. The APP indicated angle is a range of values indicating a low percentage when the accelerator pedal is not depressed to a high percentage when the accelerator pedal is fully depressed.

APP Sensor 1
This parameter displays the voltage signal sent to the ECM from accelerator pedal position (APP) sensor 1 of the APP sensor assembly. APP sensor 1 is a range of values indicating a low voltage when the accelerator pedal is not depressed to a high voltage when the accelerator pedal is fully depressed.

APP Sensor 2
This parameter displays the voltage signal sent to the ECM from accelerator pedal position (APP) sensor 2 of the APP sensor assembly. APP sensor 2 is a range of values indicating a high voltage when the accelerator pedal is not depressed to a middle voltage when the accelerator pedal is fully depressed.

APP Sensor 3
This parameter displays the voltage signal sent to the ECM from accelerator pedal position (APP) sensor 3 of the APP sensor assembly. APP sensor 3 is a range of values indicating a high voltage when the accelerator pedal is not depressed to a middle voltage when the accelerator pedal is fully depressed.

Balancing Rate Cyl. 1
This parameter displays the adjustment in fuel volume for cylinder 1 at low engine speed area (from idle to around 1000 RPM) as calculated by the ECM. The scan tool will display a negative balancing rate if the fuel volume is lowered. The scan tool will display a positive balancing rate if the fuel volume is increased. If there is a cylinder that is excessively high or low, it may indicate a faulty injector, weak or slightly seized cylinder or an incorrectly programmed fuel injector flow rate.

Balancing Rate Cyl. 2
This parameter displays the adjustment in fuel volume for cylinder 2 at low engine speed area (from idle to around 1000 RPM) as calculated by the ECM. The scan tool will display a negative balancing rate if the fuel volume is lowered. The scan tool will display a positive balancing rate if the fuel volume is increased. If there is a cylinder that is excessively high or low, it may indicate a faulty injector, weak or slightly seized cylinder or an incorrectly programmed fuel injector flow rate.

Balancing Rate Cyl. 3
This parameter displays the adjustment in fuel volume for cylinder 3 at low engine speed area (from idle to around 1000 RPM) as calculated by the ECM. The scan tool will display a negative balancing rate if the fuel volume is lowered. The scan tool will display a positive balancing rate if the fuel volume is increased. If there is a cylinder that is excessively high or low, it may indicate a faulty injector, weak or slightly seized cylinder or an incorrectly programmed fuel injector flow rate.

Balancing Rate Cyl. 4
This parameter displays the adjustment in fuel volume for cylinder 4 at low engine speed area (from idle to around 1000 RPM) as calculated by the ECM. The scan tool will display a negative balancing rate if the fuel volume is lowered. The scan tool will display a positive balancing rate if the fuel volume is increased. If there is a cylinder that is excessively high or low, it may indicate a faulty injector, weak or slightly seized cylinder or an incorrectly programmed fuel injector flow rate.

BARO Sensor
This parameter displays the voltage signal from the barometric pressure (BARO) sensor internal to the ECM. BARO sensor has a range of values from a low voltage in high altitude to high voltage in low altitude.

BARO
This parameter displays the barometric pressure as calculated by the ECM using barometric pressure (BARO) sensor inside of the ECM.

Basic Fuel Rate
This parameter displays the basic fuel rate as calculated by the ECM based on engine speed and accelerator pedal position. The scan tool will display more fuel rate if the engine load is increased as the accelerator pedal is stepped on at constant engine speed.

Battery Voltage
This represents the system voltage measured by the ECM at the ECM battery voltage feed circuit.

Boost Pressure Sensor
This parameter displays the amount of turbo boost pressure in the intake manifold. True boost pressure is determined by subtracting BARO from the actual reading.

Cam Signal Present
This parameter displays the status of the Camshaft Position (CMP) Sensor signal to the ECM. The scan tool will display Yes or No. Yes indicates the CMP signal is being received by the ECM. No indicates the CMP signal is not being received by the ECM.

Clutch Pedal Switch
This parameter displays the current state of the clutch pedal switch when the vehicle has a manual transmission.

Crank Signal Present
This parameter displays the status of the Crankshaft Position (CKP) Sensor signal to the ECM. The scan tool will display Yes or No. Yes indicates the CKP signal is being received by the ECM. No indicates the CKP signal is not being received by the ECM.

Cruise Control Active
This parameter displays the status of the cruise control system as determined by the ECM. The scan tool will display Yes when the cruise control system is in control of vehicle speed. The scan tool will display No when the cruise control system is not operating.

Cruise Main Lamp Command
This parameter displays the commanded state of the cruise main lamp control circuit. The cruise main lamp should be On when the cruise control main switch is pushed and the scan tool indicates the Cruise Main Lamp Command is On. The cruise control main lamp should be Off when the cruise control main switch is pushed again and the scan tool indicates the Cruise Main Lamp Command is Off.

Cruise On/Off Switch
This parameter displays the state of the Cruise On/Off switch input to the ECM. When the Cruise Main switch is pushed, the scan tool displays On.

Cruise Release Brake Switch
This parameter displays the state of the Cruise Release Brake Switch as determined by the ECM. The scan tool will display Released or Applied. Released indicates the brake pedal is not being pushed down, allowing the cruise control to be enabled. Applied indicates the brake switch is being applied, disabling cruise control operation.

Cruise Resume/Accel. Switch
This parameter displays the state of the Cruise Resume/Accel, switch input to the ECM. When the Resume/Accel, switch is pushed, the scan tool displays On.

Cruise Set/Coast Switch
This parameter displays the state of the Cruise Set/ Coast switch input to the ECM. When the Set/Coast switch is pushed, the scan tool displays On.

Cruise Set Lamp Command
This parameter displays the commanded state of the cruise set lamp control circuit. The cruise set lamp should be ON when the cruise control set/coast switch is pushed in cruise control enable condition and the scan tool indicates the Cruise Set Lamp Command is On.

Desired FRP Regulator
This parameter displays the fuel rail pressure (FRP) regulator control current by the ECM based on current sensor inputs. This can be compared to the Actual FRP Current to determine FRP regulator accuracy or fuel supply pump problems.

Desired Fuel Rail Pressure
This parameter displays fuel rail pressure desired by the ECM based on current sensor inputs. This can be compared to the actual fuel rail pressure to determine sensor accuracy or fuel pressure problems.

Desired Idle Speed
This parameter displays the idle speed requested by the ECM. The ECM will compensate for various engine loads based on engine coolant temperature (ECT) to keep the engine at the desired speed.

DTC Set This Ignition
This parameter displays Yes if a diagnostic trouble code (DTC) set during the current ignition cycle.

ECT Sensor
This parameter displays the temperature of the engine coolant based on a voltage input from the engine coolant temperature (ECT) sensor to the ECM. The scan tool will display a low temperature when signal voltage is high, and a high temperature when the signal voltage is low.

EGR Learned Minimum Position
This parameter displays the learned position at the EGR valve closed position using the signal from the EGR valve position sensor.

EGR Position Sensor
This parameter displays the EGR valve position calculated by the ECM using the signal from EGR position sensor. The EGR valve current position is a range of values indicating a low percentage when the EGR valve is closed to a high percentage when the ERG valve is opened.

EGR Position Sensor
This parameter displays the voltage signal sent to the ECM from the EGR position sensor. EGR Position Sensor is a range of values indicating a low voltage when the EGR valve is closed to a high voltage when the EGR valve is opened.

EGR Position Variance
This parameter displays the amount of the EGR valve deviation between the desired EGR valve position and the actual EGR valve position using the signal from the EGR valve position sensor.

EGR Solenoid Command
This parameter displays the EGR valve control duty ratio commanded by the ECM using the signal from engine speed, engine coolant temperature and injection volume.

Engine Load
This parameter displays the engine load in percent based on inputs to the ECM from various engine sensors. The scan tool will display a low percentage when the engine is at idle with little or no load. The scan tool will display a high percentage when the engine is running at high engine speed under a heavy load.

Engine Run Time
This parameter displays the time elapsed since the ignition switch is ON. The scan tool will display the time in hours, minutes and seconds. The engine run time will reset to zero as soon as the ignition switch is OFF.

Engine Speed
This parameter displays the speed of the crankshaft as calculated by the ECM based on inputs from the crankshaft position (CKP) sensor or camshaft position (CMP) sensor. The scan tool will display the engine speed in revolution per minute (RPM).

Exhaust Brake Relay (If Equipped)
This parameter displays a feedback signal based on the signal from the exhaust brake control relay. The scan tool will display On or Off. On indicates the exhaust brake control relay has closed, allowing voltage to the exhaust brake magnetic valve and intake throttle solenoid. Off indicates the exhaust brake control relay is open and exhaust brake will not engage.

Exhaust Brake Relay Command (If Equipped)
This parameter displays the commanded state of the exhaust brake control relay circuit. The scan tool will display On or Off. On indicates the exhaust brake control relay circuit is being energized by the ECM. Off indicates the exhaust brake control relay is not being commanded On by the ECM.

Exhaust Brake Switch (If Equipped)
This parameter displays the input status of the exhaust brake switch to the ECM. The scan tool will display On or Off. On indicates the exhaust brake switch is closing the exhaust brake request circuit to the ECM. Off indicates the exhaust brake switch is open.

Final Fuel Rate
This parameter displays the final fuel rate as calculated by the ECM. The basic fuel rate calculated from the engine speed and accelerator pedal position is compared with the fuel rate which added the compensation by the various sensor inputs to the maximum fuel rate calculated from the engine speed. The fewer one is determined as the final fuel rate.

Final Fuel Rate Correction
This parameter displays the compensated final fuel rate as calculated by the ECM based on the final fuel rate and engine running condition (fuel temperature and balancing rate).

FRP Regulator Command
This parameter displays the fuel rail pressure (FRP) regulator control duty ratio signal based on inputs to the ECM from various engine sensors. The scan tool will display a low percentage when the FRP regulator is controlled to open (fuel supply quantity to the fuel rail is increased). The scan tool will display a high percentage when the FRP regulator is controlled to close (fuel supply quantity to the fuel rail is reduced).

FRP Regulator Fuel Flow
This parameter displays the commanded fuel quantity of the fuel rail pressure (FRP) regulator to the fuel rail.

Fuel Rate at Start
This parameter displays the fuel rate at startup as calculated by the ECM based on the signal from the engine coolant temperature (ECT) sensor and starter switch input signal. The scan tool will display more fuel rate if the engine coolant is cold.

Fuel Temperature Sensor
This parameter displays the temperature of the fuel based on a voltage input from the fuel temperature (FT) sensor to the ECM. The scan tool will display a low temperature when signal voltage is high, and a high temperature when the signal voltage is low.

Glow Plug Lamp Command
This parameter displays the commanded state of the glow indicator lamp control circuit. The glow indicator lamp should be On when the scan tool indicates the Glow Plug Lamp Command is On. The glow indicator should be Off when the scan tool indicates the Glow Plug Command is Off.

Glow Plug Relay
This parameter displays the commanded state of the glow plug relay control circuit. The scan tool will display On or Off. On indicates the glow plug relay control circuit is being grounded by the ECM, allowing voltage to the glow plugs. Off indicates the glow plug relay is not being commanded on by the ECM.

IAT Sensor
This parameter displays the temperature of the intake air based on a voltage input from the intake air temperature (IAT) sensor to the ECM. The scan tool will display a low temperature when signal voltage is high, and a high temperature when the signal voltage is low. Note that the IAT sensor is internal to the MAF sensor and the MAF sensor is heated.

Idle Up Sensor
This parameter displays the voltage signal sent to the ECM from the idle up sensor. The idle up sensor has a range of values indicating a low voltage when the idle up sensor rotates in a counterclockwise direction to a high voltage when the idle up sensor rotates in a clockwise direction.

Ignition 1 Signal
This parameter displays the voltage measured at the ignition feed circuit of the ECM. Voltage is applied to the ECM when the ignition switch is ON position.

Injector 1 Command
This parameter is the time the ECM turns on the fuel injector for cylinder No. 1. The scan tool will display a higher value with a longer pulse width, or a lower value with a shorter pulse width.

Intake Throttle Solenoid
This parameter displays a feedback signal based on the signal from the exhaust brake control relay. The scan tool will display On or Off. On indicates the exhaust brake control relay has closed, allowing voltage to the exhaust brake magnetic valve and intake throttle solenoid. Off indicates the exhaust brake control relay is open and exhaust brake will not engage.

MAF Sensor
This parameter displays the air flow into the engine as calculated by the ECM based on the mass air flow (MAF) sensor input. The scan tool will display a high value at higher engine speeds, and a low value at idle.

MAF Sensor
This parameter displays the voltage signal sent to the ECM from the mass air flow (MAF) sensor. The scan tool will display a high voltage at higher engine speeds, and a low voltage at idle.

Main Injection Fuel Rate
This parameter displays a main injection quantity desired by the ECM based on current driving conditions.

Main Injection Timing
This parameter is the injection timing calculated by the ECM based on the CKP sensor and CMP sensor inputs using a target injection timing map. This timing is compensated by engine coolant temperature, altitude, and intake air temperature, etc.

MIL Command
This parameter displays the commanded state of the malfunction indicator lamp (MIL) control circuit. The MIL should be on when the scan tool indicates the MIL Command is On. The MIL should be off when the scan tool indicates the MIL Command is Off The ECM will command the MIL On when the ignition is On with the engine Off in order to perform a bulb check.

Pilot Injection Fuel Rate
This parameter displays a pilot injection quantity desired by the ECM based on current driving conditions.

Power Relay Status
This parameter displays the commanded state of the ECM Main Relay control circuit. The scan tool will display On or Off. On indicates the ECM Main Relay control circuit is being grounded by the ECM, allowing the main relay to supply voltage to the other circuits of the ECM. Off indicates the main relay is not being commanded On by the ECM.

PTO Enable (If Equipped)
This parameter displays input status of the PTO switch to the ECM. The scan tool will display Yes or No. Yes indicates the PTO switch is pushed On, supplying ignition voltage to the ECM.

PTO Engage Relay Command (If Equipped)
This parameter displays the commanded state of the PTO relay control circuit. The scan tool will display On or Off. On indicates the PTO relay control circuit is being grounded by the ECM, allowing voltage to the load engage switch. Off indicates the PTO relay is not being commanded on by the ECM.

PTO Engine Shutdown Signal (If Equipped)
This parameter displays the input status of the PTO engine shutdown switch to the ECM. The scan tool will display Yes or No. Yes indicates the PTO engine shutdown switch is closed, grounding the engine shutoff signal circuit to the ECM. No indicates the engine shutoff switch is open, allowing normal engine and PTO operation.

PTO Feedback Signal (If Equipped)
This parameter displays a feedback signal based on the signal from the PTO relay feedback switch. The scan tool will display On or Off. On indicates the PTO relay has closed, allowing voltage to the load engage switch. Off indicates the PTO relay is open and the PTO will not engage.

PTO Remote Throttle Sensor (if Equipped)
This parameter displays the voltage signal sent to the ECM from the PTO throttle sensor. The PTO throttle sensor is a range of values indicating a low voltage when the throttle sensor is not operated to a high voltage when the throttle sensor is fully operated.

Start Up ECT
This parameter displays the engine coolant temperature at start up, as calculated by the ECM based on the input from the engine coolant temperature sensor. The scan tool will display a higher value at higher start up temperatures.

Start Up Fuel Temperature
This parameter displays the fuel temperature (FT) at start up, as calculated by the ECM based on the input from the FT sensor. The scan tool will display a higher value at higher start up temperature.

Start Up IAT
This parameter displays the intake air temperature (IAT) at start up, as calculated by the ECM based on the input from the IAT sensor. The scan tool will display a higher value at higher start up temperature.

Starter Relay Status
This parameter displays the input status state of the starter relay. The scan tool will display On or Off. On indicates the ignition switch is at the start position, allowing voltage to the starter relay. Off indicates the ignition switch is anything other than the start position and starter relay will not engage.

Stoplamp Pedal Switch
This parameter displays the state of the brake pedal as determined by the ECM based on an input from the stop lamp pedal switch. This switch turns on the stop lamps when the brake pedal is depressed. The scan tool will display Applied when the brake pedal is depressed.

Supply Pump Adjustment
The ECM has ability to learn the fuel supply pump variation and this parameter displays the adjustment current supplied to the fuel rail pressure (FRP) regulator. Note that the supply pump adjustment value must be reset when the fuel supply pump or engine is replaced, or an ECM from another vehicle is installed.

Supply Pump Status
This parameter displays the learning state of the fuel supply pump. The scan tool will display Not Learn, Tentative, Learning or Learned. Not Learn indicates initialized state that is replaced to a new ECM or adjustment value is reset. Tentative indicates tentative learning state that is started at idle speed as soon as possible. After engine is warm upped, real leaning will start at idle speed. Learning indicates real learning state. Learned indicates learning process is completed state.

SVS Lamp Command
This parameter displays the commanded state of the service vehicle soon (SVS) lamp control circuit. The SVS lamp should be On when the scan tool indicates the SVS Lamp Command is On. The SVS lamp should be Off when the scan tool indicates the SVS Lamp Command is Off. The ECM will command the SVS lamp On when the ignition is On with the engine Off in order to perform a bulb check.

Vehicle Speed Sensor
This parameter displays the vehicle speed calculated by the ECM based on an input from the vehicle speed sensor (VSS). The scan tool will display a high value at higher vehicle speeds, and a low value at lower vehicle speeds.