The Engine Control Module Scan Tool Data Definitions contains a brief description of all engine control module (ECM) related parameters 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.

5 volt Reference 1: This parameter displays the voltage sensed on the 5 volt reference 1 circuit at the control module. The scan tool will display a higher value at higher voltage. The scan tool will display a lower value at lower voltage.

5 volt Reference 2: This parameter displays the voltage sensed on the 5 volt reference 2 circuit at the control module. The scan tool will display a higher value at higher voltage. The scan tool will display a lower value at lower voltage.

5 volt Reference 3: This parameter displays the voltage sensed on the 5 volt reference 3 circuit at the control module. The scan tool will display a higher value at higher voltage. The scan tool will display a lower value at lower voltage.

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

Actual Fuel Rail Pressure: This parameter displays the fuel rail pressure as calculated by the control module 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 MPa or psi.

After Injection Fuel Rate: This parameter displays the quantity of fuel injected during the post injection during regeneration as calculated by the ECM.

APP Indicated Angle: This parameter displays the angle of the accelerator pedal as calculated by the control module using the signals from the accelerator pedal position sensors. The accelerator pedal position (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 control module from 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 control module from APP sensor 2 of the APP sensor assembly. APP sensor 2 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 3: This parameter displays the voltage signal sent to the control module 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 low voltage when the accelerator pedal is fully depressed.

Balancing Rate Cyl. 1-6: These parameter display the adjustment in fuel volume for each cylinder as calculated by the control module. 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.

BARO: This parameter displays the barometric pressure as calculated by the control module using the signal from the barometric pressure (BARO) sensor. The scan tool will display a high value at higher barometric pressures, such as sea level. The scan tool will display a lower value at lower barometric pressures, such as higher altitude locations.

BARO: This parameter displays the voltage signal received by the control module using the signal from the Barometric Pressure (BARO) sensor measured when the ignition is turned on. The scan tool will display a higher voltage at lower altitude. The scan tool will display a lower voltage at higher altitude.

Basic Fuel Rate: This parameter indicates the basic PC valve on time as commanded by the ECM.

Battery Voltage: This parameter displays the voltage measured at the battery circuit of the control module. Voltage is applied to the control module from the battery at all times. The scan tool will display a low value when sensed battery voltage is low, and a high value when sensed battery voltage is high.

Boost Pressure Sensor: This parameter indicates the turbocharger boost pressure inside the engine as calculated by the control module based on the signal from the boost pressure sensor. The scan tool will display a higher value under heavy load, and a lower value at idle.

CAM Signal Present: This parameter displays the state of the CAM signal as determined by the control module. The scan tool will display Yes if the CAM signal is being received by the control module. The scan tool will display No if the CAM signal is missing.

Catalytic Converter 1: This parameter displays the temperature of Catalytic converter sensor 1. When the DOC temperature is low, the scan tool will display a low temperature. When the DOC temperature is high, the scan tool will display a high temperature.

Catalytic Converter 2: This parameter displays the temperature of Catalytic converter sensor 2. When the DOC temperature is low, the scan tool will display a low temperature. When the DOC temperature is high, the scan tool will display a high temperature.

Clutch Pedal Switch: This parameter displays the current state of the clutch pedal as determined by the control module. The scan tool will display Applied when the clutch pedal is depressed, and released when the clutch pedal is not depressed.

Crank Signal Present: This parameter displays the state of the CKP signal as determined by the control module. The scan tool will display Yes if the CKP signal is being received by the control module. The scan tool will display No if the CKP signal is missing.

Cruise Control Active: This parameter displays the status of the cruise control system as determined by the control module. 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 On/Off Switch: This parameter displays the state of the on/off switch input to the control module . The scan tool will display On when the cruise ON/OFF switch is ON. The scan tool will display OFF when the cruise ON/OFF switch is OFF.

Cruise Resume/Accel Switch: This parameter displays the state of the Resume/Accel switch input to the control module. When the cruise control switch is in the ON position and the Resume/Accel switch is activated, the scan tool displays On. When the Resume/Accel switch is released the scan tool displays Off.

Cruise Set/Coast Switch: This parameter displays the state of the Set/Coast switch input to the control module from the cruise control system. When the cruise control switch is in the ON position and the Set/Coast switch is activated, the scan tool displays On. When the Set/Coast switch is released the scan tool displays Off.

Desired Boost: This parameter displays the desired amount of Boost pressure as calculated by the ECM based on various sensors.

Desired EGR Position: This parameter displays the position of the exhaust gas recirculation (EGR) valve commanded by the control module. The scan tool will display 0 percent when the control module is commanding the EGR valve closed. The scan tool will display a higher percentage when the EGR valve is commanded open.

Desired FRP Regulator: This parameter displays the desired current draw of the FRP regulator as calculated by the control module. The scan tool will display a low value if the regulator is commanded open, and a higher value when the regulator is commanded closed.

Desired Fuel Rail Pressure: This parameter displays the desired fuel rail pressure as calculated by the control module. This value is calculated based on engine speed, engine load, and sensor inputs. The scan tool will display a higher value at higher engine speeds and loads, and a lower value at idle.

Desired Idle Speed: This parameter displays the engine idle speed in RPM as commanded by the control module. The control module compensates for various engine loads in order to maintain the desired engine speed at idle. This parameter is not valid unless the engine is running.

Desired TC Vane Position: This parameter displays the position of the turbocharger vane position sensor as the turbocharger vane position is commanded by the control module. The scan tool will display 0 percent when the control module is commanding the vanes open. The scan tool will display a higher percentage when the vanes are commanded closed.

Des. TC Vane Pos. Ctrl. Solenoid: This parameter displays the desired current draw of the turbocharger vane position control solenoid valve as calculated by the control module. The scan tool will display a high value if the solenoid is commanded open, and a lower value when the solenoid is commanded closed.

DPF Error Count: This parameter displays the number of unsuccessful regeneration that have occurred.

DPF Manual Regenerates On Time: This parameter displays the amount of time since the manual regeneration switch has been activated.

DPF Regeneration Status: This parameter displays the status of the current regeneration cycle. The parameter will display complete if the last regeneration was successful. If the regeneration was not successful, the parameter will display a different message.

DPF Regeneration Complete Status: This parameter displays the status of the last DPF regeneration.

DPF Regeneration Switch: This parameter displays the current status of the DPF manual regeneration switch. The parameter will display yes if the switch is ON, and No if the switch is off. The switch is normally OFF except when toggled by the driver, providing a momentary input.

DPF Regeneration Time: This parameter displays the length of time that was needed to perform the last regeneration.

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

ECT Sensor: This parameter displays the temperature of the engine coolant calculated by the control module, based on the input from the engine coolant temperature sensor. When the coolant temperature is low, the scan tool will display a low temperature. When the coolant temperature is high, the scan tool will display a high temperature.

EGR Learned Minimum Position: This parameter displays the closed position of the EGR valve during the last EGR position learn cycle.

EGR Position Sensor: This parameter displays EGR valve position as calculated by the control module based on an input from the EGR valve position sensor. The scan tool will display a lower value when the EGR valve is closed, and a higher value when the EGR valve is open.

EGR Position Variance: This parameter displays the difference between the desired EGR valve position calculated by the control module and the actual EGR position input from the EGR valve position sensor. The scan tool will display a higher value if the difference is large, and a lower value if the difference is small.

EGR Solenoid Command: This parameter displays the duty cycle commanded by the control module for the EGR valve. The scan tool will display a high percentage when the EGR valve is commanded open. The scan tool will display a low percentage when the EGR valve is commanded closed.

EGR Temperature Sensor 1: This parameter displays the temperature of the exhaust gases before the EGR cooler.

EGR Temperature Sensor 2: This parameter displays the temperature of the exhaust gases after the EGR cooler.

EGT Sensor 1: This parameter displays the temperature of the exhaust gases after the converter.

EGT Sensor 2: This parameter displays the temperature of the exhaust gases after the DPF.

Engine Oil Level Switch: This parameter displays the status of the engine oil level switch as determined by the control module. The control module uses this information to turn on the low engine oil lamp if the engine oil level remains approximately 1 quart low for a sufficient amount of time. The scan tool will display Low when the engine oil level is low. The scan tool will display OK when the engine oil level is correct.

Engine Oil Life Remaining: This parameter displays the amount engine oil life remaining before requiring an oil change based on calculations by the control module. The scan tool will display lower values as the engine oil life approaches 0 miles.

Engine Oil Pressure Sensor: This parameter displays the pressure of the engine oil as calculated by the control module using a signal from the engine oil pressure (EOP) sensor. The scan tool will display oil pressure when the engine is running. The engine oil pressure sensor has a range of values indicating a low value when the oil pressure is low to a high value when the oil pressure is high.

Engine Run Time: This parameter displays the time elapsed since the engine was started. The scan tool will display the time in hours, minutes and seconds. The engine run time will reset to zero when the engine stops running.

Engine Speed: This parameter displays the speed of the crankshaft as determined by the control module using an input from the CKP sensor. The scan tool will display a high value at high engine speeds and a low value at low engine speeds.

Exhaust Brake Relay Command: This parameter displays the commanded state of the exhaust brake relay control circuit. The scan tool will display ON or OFF. ON indicates the exhaust brake relay control circuit is being grounded by the control module, allowing voltage to the exhaust brake solenoid. OFF indicates the exhaust brake relay is not being commanded on by the control module.

Exhaust Brake Switch: This parameter displays the input status of the exhaust brake switch to the control module. The scan tool will display ON or OFF. ON indicates the exhaust brake switch is closing the exhaust brake request circuit to the control module. OFF indicates the exhaust brake switch is open.

Exhaust Brake Throttle Command: This parameter displays the status of the exhaust brake throttle. The throttle is used during DPF regeneration. Yes indicates the throttle is being commanded closed. No indicates the throttle is commanded open. The throttle is normally in an open position when not commanded.

Exhaust Pressure Sensor: This parameter displays the pressure in the exhaust system before the DPF.

Exhaust Pressure Variance Entrance: This parameter displays the pressure difference between the inlet and the outlet of the DPF.

Final Fuel Rate: This parameter indicates the actual fuel rate as calculated by the ECM. The ECM attempts to adjust this rate to bring it close to the Basic Fuel Rate.

FRP Regulator Command: This parameter displays the current draw of the fuel pressure regulator through the control module. The scan tool will display a higher value for a higher commanded current, and a lower value for a lower commanded current.

FRP Regulator Fuel Flow Command: This parameter displays the fuel flow through the fuel pressure regulator as calculated by the control module based on engine speed, engine load, fuel pressure regulator current, and fuel pressure sensor inputs. The scan tool will display higher values at higher engine speeds and loads, and lower values at idle.

Fuel Level Sensor: This parameter displays the approximate fuel level in the fuel tank as calculated by the control module based on inputs from the fuel level sensors. The scan tool will display a low value when the fuel level in the tank is low or near empty. The scan tool will display a high value when the fuel level in the tank is high or near full.

Fuel Level Sensor Rear Tank: This parameter displays the voltage received by the control module from the sensor used to monitor the fuel level inside the rear fuel tank. The scan tool will display a low voltage when the fuel level in the tank is low or near empty. The scan tool will display a high voltage reading when the fuel level in the tank is high or near full.

Fuel Rate at Start: This parameter indicates the fuel rate at startup.

Fuel Rate Correction: This parameter displays the average adjustment and fuel volume for each cylinder as calculated by the control module. The scan tool will display a negative value if the fuel volume is lowered. The scan tool will display a positive value if the fuel volume is increased.

Fuel Tank Rated Capacity: This parameter displays the rated maximum quantity of fuel the fuel tank will hold. This is calibrated in the control module to match the vehicle.

Fuel Temperature Sensor: This parameter displays the current fuel temperature as calculated by the control module based on input from the fuel temperature sensor. The scan tool will display a higher value at higher fuel temperatures. The scan tool will display a lower value at lower fuel temperatures.

GEN L-Terminal Signal: This parameter indicates whether the control module is allowing the generator to operate. The control module can disable the generator under certain conditions. The scan tool will display voltage if the control module is allowing generator operation, while no voltage indicates that the control module is not allowing generator operation.

Glow Plug Relay : This parameter displays the commanded state of the glow plug system. The scan tool will display ON if the glow plugs are being commanded on by the glow plug controller. The scan tool will display OFF if the glow plugs are not being commanded on by the glow plug controller.

High Idle Switch: This parameter displays the state of the high idle request input to the control module from the high idle switch. The scan tool will display ON or OFF. ON indicates the control module is receiving a request from the high idle switch to increase engine speed. OFF indicates the control module is not receiving a request from the high idle switch to increase engine speed.

IAF Valve Position: This parameter displays the commanded position of the Intake Air Flow Valve.

IAT Sensor: This parameter displays the temperature of the air entering the engine air duct as calculated by the control module based on the input from the intake air temperature 1 sensor. The scan tool will display a low value when the air temperature is low, and a high value when the air temperature is high.

Ignition 1 Signal: This parameter displays the voltage measured at the ignition 1 circuit of the control module. Voltage is applied to the control module when the ignition switch is in the ignition 1 position. The scan tool will display a low value when the voltage is low. The scan tool will display a high value, such as battery voltage, when the voltage is higher.

Injector 1-6 Command: This parameter displays the commanded on time of each fuel injector by the control module. The scan tool will display a low value at idle, and a high value during high engine speeds and loads.

Intake Air Heater Relay Command: This parameter displays the commanded state of the intake air heater by the control module. Scan tool will display ON if the heater is commanded on. The scan tool will display OFF if the heater is commanded off.

Low Coolant Level: This parameter displays the current status of the low coolant level switch. The scan tool will indicate Yes if the coolant level is low. The scan tool will display No if the coolant level is full.

MAF Sensor: This parameter indicates the quantity calculated by the control module based on a signal from the mass air flow (MAF) Sensor. The scan tool will display a high value at high engine speeds, and a low value at low engine speeds.

MAF Sensor (volts): This parameter indicates the voltage signal received from the MAF sensor by the control module. The scan tool will display a high value at high engine speeds, and a low value at low engine speeds.

Main Injection Timing: Indicates the current timing of the main injection pulse as calculated by the control module. The scan tool will display a higher value for a main injection event farther from top dead center (TDC). The Scan tool will display a lower value for a main injection event closer to TDC.

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

PCM Reset: This parameter indicates when the internal control module resets. The scan tool displays YES when an internal PCM reset has occurred. The scan tool displays NO under the normal operating conditions.

PNP Switch: This parameter indicates the range selection of the automatic transmission as calculated by the control module based on input from the park/neutral position (PNP) switch. The scan tool will display, In Gear, Park, or Neutral depending on the PNP switch position.

Power Relay Status: This parameter displays the commanded state of the power relay control circuit. The scan tool will display ON or OFF. ON indicates the power relay control circuit is being grounded by the control module, allowing voltage to the other circuits of the control module. OFF indicates the power relay is not being commanded on by the control module.

PTO Enable: This parameter indicates all parameter have been met to enable the power take off (PTO), and the control module has determined that the power take off (PTO) is engaged.

PTO Engage Relay Command: 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 control module, allowing voltage to the load engage switch. OFF indicates the PTO relay is not being commanded on by the control module.

PTO Engine Shutdown Signal: This parameter displays the input status of the PTO engine shutdown switch to the control module. 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 control module. OFF indicates the engine shutoff switch is open, allowing normal engine and PTO operation.

PTO Feedback Signal: This parameter displays the state of the PTO based on the signal from the switched side of the PTO relay. The scan tool will display Relay On or Relay Off. Relay On indicates the PTO relay has closed, allowing voltage to the load engage switch. Relay Off indicates the PTO relay is open and the PTO will not engage.

Reverse Enable: This parameter displays the gear selection of the manual transmission as calculated by the control module based on input from the Reverse switch. The scan tool will display YES if the reverse switch is closed. The scan tool will display NO if the reverse switch is open.

Start Up ECT: This parameter Indicates the engine coolant temperature at engine start up as calculated by the control module based on the signal from the engine coolant temperature (ECT) sensor. The scan tool will display a higher value on a warmer engine, and a lower value on a colder engine.

Starter Relay Command: This parameter displays the commanded state of the starter relay by the ECM. On indicates the relay is commanded ON. Off indicates that the starter relay is not commanded ON.

Stop Lamp Pedal Switch: This parameter displays the state of the brake pedal as determined by the stop lamp pedal switch. This switch turns on the stop lamp when the brake pedal is depressed. The scan tool will display Applied when the brake pedal is depressed, and Released when the brake pedal is not depressed.

TC Vane Learned Open Position: This parameter displays the difference between the last learned open position of the turbocharger vanes and the current open learned position. The scan tool will display a higher value for a larger difference. The scan tool will display a lower value for a smaller difference.

TC Vane Position Sensor: This parameter displays the current commanded state of the turbocharger vane position control solenoid valve by the control module. The scan tool will display a higher value as the solenoid is commanded open. The scan tool will display a lower value as the solenoid is commanded closed.

TC Vane Position Control Solenoid: This parameter displays the current draw of the vane position control solenoid through the control module. The scan tool will display a high current draw when the turbocharger vanes are being commanded closed. The scan tool will display a lower current draw when the turbocharger vanes are being commanded open.

Two-Speed Axle Switch: This parameter displays the status of the two-speed axle switch.

Vehicle Speed Sensor: This parameter indicates the vehicle speed as calculated by the control module based on a signal from the vehicle speed sensor (VSS). The scan tool will display a higher value at higher vehicle speeds, and a lower value at lower vehicle speeds.

Wait to Start: This parameter displays the commanded state of the Wait to Start lamp by the control module. The scan tool will display ON if the lamp is commanded ON. The scan tool will display OFF if the lamp is not commanded ON. Indicates the commanded state of the Wait to Start lamp.