Part 1

Scan Tool Data Definitions (ECM)

The Engine Scan Tool Data Definitions contains a brief description of all engine related parameters available on the scan tool. The list is 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.

5-Volt Reference 2
- This parameter displays the voltage sensed on the 5-volt reference 2 circuit at the control module.

4WD Low Signal
- This parameter displays the state of the transfer case based on the signal from the four wheel drive (4WD) low switch. The scan tool will display Enabled or Disabled. Enabled indicates the transfer case is in 4WD low gear and the 4WD low switch is closed, completing the low signal circuit. Disabled indicates the transfer case is not in 4WD low gear and the 4WD low switch is open.

4WD Signal
- This parameter displays the state of the transfer case based on the signal from the front axle indicator switch. The scan tool will display Enabled or Disabled. Enabled indicates the front axle is locked in four wheel drive and the front axle indicator switch is closed, supplying voltage to the controller on the axle switch signal circuit. Disabled indicates the transfer case is not in four wheel drive and the front axle indicator switch is open.

A/C Compressor Cycling Switch
- This parameter displays the state of the air conditioning (A/C) compressor cycling switch as determined by the control module. The scan tool will display Normal or Low Pressure. Normal indicates the A/C system has enough refrigerant to close the A/C compressor cycling switch, allowing the A/C compressor to engage. Low Pressure indicates the A/C refrigerant system has low pressure and the A/C compressor cycling switch is open.

A/C Relay Circuit Status
- This parameter displays the status of the output driver for the A/C clutch relay control circuit. The scan tool will display OK, Incomplete, Short B+, Short Gnd/Open. OK indicates that no circuit faults are detected during the current test. Fault indicates that a short or open circuit/component exists, electronically disconnecting the circuit/component from the control module.

A/C Relay Command
- This parameter displays the commanded state of the air conditioning (A/C) clutch relay control circuit. The scan tool will display ON or OFF. ON indicates the A/C clutch relay control circuit is being grounded by the control module, allowing voltage to the A/C compressor clutch. OFF indicates the A/C clutch relay is not being commanded on by the control module.

A/C Request Signal
- 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. 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.

Air Flow Calculated
- This parameter displays the air flow of the engine as calculated by the control module using information from the manifold absolute pressure (MAP) sensor. The scan tool will display a range of values indicating a high air flow when MAP pressure is high and a low air flow when MAP pressure is low. This value is listed in g/s.

Air Fuel Ratio
- This parameter displays the ratio of air to fuel as calculated by the control module based on various sensor inputs. The scan tool will display a lower air fuel ratio when a richer air to fuel mixture is commanded. The scan tool will display a higher air fuel ratio when a leaner air to fuel mixture is commanded. In closed loop operation the air fuel ratio should normally be around 14.2-14.7 to 1.

AIR Pump Relay Command
- This parameter displays the commanded state of the secondary air injection (AIR) pump relay control circuit. The scan tool will display ON or OFF. ON indicates the AIR pump relay control circuit is being grounded by the control module, allowing voltage to the AIR pump. OFF indicates the AIR pump relay is not being commanded on by the control module.

Ambient Air Temperature
- This parameter displays the ambient, outside, air temperature as calculated by the control module.

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 APP indicated angle is a range of values indicating a low percentage when the accelerator pedal is not pressed to a high percentage when the accelerator pedal is fully pressed.

APP Sensor 1
- This parameter displays the voltage signal sent to the control module 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 pressed to a high voltage when the accelerator pedal is fully pressed.

APP Sensor 1
- This parameter displays the angle of the accelerator pedal position (APP) sensor 1 as calculated by the control module using the signal from the APP sensor 1. APP sensor 1 is a range of values indicating a low percentage when the accelerator pedal is not pressed to a high percentage when the accelerator pedal is fully pressed.

APP Sensor 1 and 2
- This parameter displays the results of a control module test that compares the signals from the accelerator pedal position (APP) sensors 1 and 2. The scan tool will display Agree or Disagree. Agree indicates that APP sensor 1 and APP sensor 2 voltages correspond to the same accelerator pedal position. Disagree indicates that APP sensor 1 and APP sensor 2 voltages correspond to different accelerator pedal positions.

APP Sensor 1 Indicated Position/APP Sensor 2 Indicated Position
- 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 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 2
- This parameter displays the voltage signal sent to the control module from accelerator pedal position (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 pressed to a high voltage when the accelerator pedal is fully pressed.

APP Sensor 2
- This parameter displays the angle of the accelerator pedal position (APP) sensor 2 as calculated by the control module using the signal form the APP sensor 2. APP sensor 2 is a range of values indicating a low percentage when the accelerator pedal is not pressed to a high percentage when the accelerator pedal is fully pressed.

BARO (Gasoline)
- This parameter displays the barometric pressure as calculated by the control module using the signal from the manifold absolute pressure (MAP) sensor measured when the ignition is turned on with the engine not running. The control module will update the barometric pressure during wide-open throttle (WOT) conditions. The scan tool will display a low value when the barometric pressure is low, and a high value when the barometric pressure is high.

BARO (Gasoline)
- This parameter displays the voltage signal received by the control module from the manifold absolute pressure (MAP) sensor measured when the ignition is turned on with the engine not running. The control module will update the barometric pressure during wide-open throttle (WOT) conditions. The scan tool will display a low value when the barometric pressure is low, and a high value when the barometric pressure is high.

BPP Circuit Signal
- This parameter displays the state of the brake pedal position switch as determined by the brake pedal switch. The scan tool will display Applied when the brake pedal is depressed, and Released when the brake pedal is not depressed.

Brake Booster Pressure
- This parameter displays the negative pressure, vacuum, internal to the brake booster assembly in kPa or inches of mercury, Hg.

Brake Booster Pressure
- This parameter displays the negative pressure, vacuum, internal to the brake booster assembly in a voltage range of 0-5 volts.

Calc. TWC Temp. Bank 1/Calc. TWC Temp. Bank 2
- This parameter displays the catalytic converter temperature as calculated by the control module.

Catalytic Converter Protection Active
- This parameter displays the state of the Catalytic Converter Protection mode.

CKP Active Counter
- This parameter displays an incrementing counter when the control module receives a signal from the crankshaft position (CKP) sensor.

CKP Resync Counter
- This parameter displays the number of times the control module re-syncs with the crankshaft position (CKP) sensor.

CKP Sensor
- This parameter displays the engine speed as calculated by the control module using the signal form the crankshaft position (CKP) sensor.

Clutch Pedal Switch
- This parameter displays the current state of the clutch pedal as determined by the control module.

CMP Active Counter
- This parameter displays an incrementing counter when the control module receives a signal form the camshaft position (CMP) sensor.

CMP Sensor
- This parameter displays the speed of the engine as calculated by the signal from the camshaft position (CMP) sensor.

CMP Sensor - High To Low
- This parameter displays the number of times the signal voltage from the camshaft position (CMP) sensor changes from high to low. The scan tool will display these transitions as counts.

CMP Sensor - Low To High
- This parameter displays the number of times the signal voltage from the camshaft position (CMP) sensor changes from low to high. The scan tool will display these transitions as counts.

Cold Start-Up
- This parameter indicates whether the engine meets the conditions for a cold start-up during the present ignition cycle. The scan tool displays Yes when the conditions for a cold start-up are met during this ignition cycle. The scan tool displays No when the conditions for a cold start-up are not met during the present ignition cycle. Conditions for a cold start-up require the coolant temperature and the intake air temperature to be below a predetermined temperature and within a certain range of each other. These conditions must occur after the engine was warmed up to a specific temperature during the previous ignition cycle.

Coolant Level Switch
- This parameter displays the level of engine coolant as determined by the control module. The control module determines the level of the coolant using the signal from a switch used to monitor the engine coolant level. The scan tool will display low when the engine coolant level is low. The scan tool will display OK when the coolant level is correct.

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 Inhibit Signal Command
- This parameter displays the commanded state of the cruise inhibit signal circuit. The scan tool will display On when the control module is inhibiting cruise control operation. The scan tool will display Off when the control module is allowing cruise control operation.

Current Gear
- This parameter displays the transmission gear commanded by the control module. The scan tool will display 1 when the control module has commanded first gear regardless of the gear selector position. The scan tool will display up to 6 depending upon which gear is commanded and what transmission is in the vehicle. The scan tool will display 9 if the transmission gear is not known.

Cycles Of Misfire Data
- This parameter displays the number of cylinder firing events that were recorded as misfires as determined by the control module.

Cylinder 1-8 IC Circuit Status
- This parameter displays the status of the output driver for the ignition control circuits. The scan tool will display OK, Incomplete, Short B+, Short Gnd/Open. The scan tool will display OK if the circuit is operating correctly. The scan tool will display a fault if there is an open, short to ground, or a short to voltage on the circuit.

Cylinder 1-8 Injector Circuit Status
- This parameter displays the status of the output driver for the injector control circuit. The scan tool will display OK, Incomplete, Short B+, Short Gnd/Open. The scan tool will display OK if the circuit is operating correctly. The scan tool will display a fault if there is an open, short to ground, or a short to voltage on the circuit.

Cylinder 1 Deact Sol CKT Status
- This parameter displays Incomplete during V8 mode. When the solenoid is commanded ON, the parameter will briefly display OK, and then display Incomplete again. This parameter will also display Short to B+ or Short to Gnd/Open when either fault is present. The engine control module (ECM) will disable the Displacement on Demand system when either fault is active.

Cylinder 1 Deact Sol Command
- This parameter displays ON when V4 mode is commanded or OFF when V8 mode is commanded.

Cylinder 4 Deact Sol CKT Status
- This parameter displays Incomplete during V8 mode. When the solenoid is commanded ON, the parameter will briefly display OK, and then display Incomplete again. This parameter will display Short to B+ or Short to Gnd/Open when either fault is present. The engine control module (ECM) will disable the Displacement on Demand system when either fault is active.

Cylinder 4 Deact Sol Command
- This parameter displays ON when V4 mode is commanded or OFF when V8 mode is commanded.

Cylinder 6 Deact Sol CKT Status
- This parameter displays Incomplete during V8 mode. When the solenoid is commanded ON, the parameter will briefly display OK, and then display Incomplete again. This parameter will display Short to B+ or Short to Gnd/Open when either fault is present. The engine control module (ECM) will disable the Displacement on Demand system when either fault is active.

Cylinder 6 Deact Sol Command
- This parameter displays ON when V4 mode is commanded or OFF when V8 mode is commanded.

Cylinder 7 Deact Sol CKT Status
- This parameter displays Incomplete during V8 mode. When the solenoid is commanded ON, the parameter will briefly display OK, and then display Incomplete again. This parameter will display Short to B+ or Short to Gnd/Open when either fault is present. The engine control module (ECM) will disable the Displacement on Demand system when either fault is active.

Cylinder 7 Deact Sol Command
- This parameter displays ON when V4 mode is commanded or OFF when V8 mode is commanded.

Cylinder Deactivation Cycles
- This parameter displays the number of times the engine switches between V8 mode, and V4 mode during each ignition cycle. The counter will reset to zero and increment again, if the count reaches 255 during the current ignition cycle.

Cylinder Deactivation Performance Test
- This parameter displays OK if all the Displacement on Demand (DoD) enabling conditions are met. The parameter displays Fault if one or more enabling conditions are out of range.

Cylinder Deactivation System Command
- This parameter displays V8 when all four Displacement on Demand (DoD) cylinder solenoids are deactivated or V4 when the DoD cylinder solenoids are activated.

Decel Fuel Cutoff
- This parameter displays the status of the operating mode used to turn OFF the fuel injectors during certain deceleration conditions. When the scan tool displays Active, the control module has turned OFF the fuel injectors. When the scan tool displays Inactive, the fuel system is operating normally.

Deact Inhibit APP High
- This parameter displays YES if the accelerator pedal position is above the calibrated value for V4 mode. A YES indication will disable the Displacement on Demand system.

Deact Inhibit APP Rate High
- This parameter displays YES if the rate of increase of the accelerator pedal position is above the calibrated value for V4 mode. A YES indication will disable the Displacement on Demand system.

Deact Inhibit Axle Torque Limiting
- This parameter displays YES, if the engine control module (ECM) determines that the axle torque is above a calibrated value. The axle torque is calculated from several different control module parameters. A Yes indication will disable the Displacement on Demand system.

Deact Inhibit Brake Booster Pressure Sensor DTC
- This parameter displays YES if DTC P0556, P0557, or P0558 is set. A YES indication will disable the Displacement on Demand system.

Deact Inhibit DLC Override
- This parameter displays YES if a condition exist that prohibits V4 mode when using the scan tool Output Control function. A YES indication will disable the Displacement on Demand system.

Deact Inhibit ECT Low
- This parameter displays YES if the engine coolant temperature is below the calibrated value. A YES indication will disable the Displacement on Demand system.

Deact Inhibit Engine Metal Temperature
- This parameter displays YES if the engine metal temperature is above a calibrated value. Engine metal temperature is calculated from several different engine control module (ECM) parameters. A YES indication will disable the Displacement on Demand system.

Deact Inhibit Engine Oil Temperature
- This parameter displays YES if the engine oil temperature is not within the calibrated range. Engine oil temperature is calculated from several different engine parameters. A YES indication will disable the Displacement on Demand system.

Deact Inhibit Engine Over Temperature Protection
- This parameter displays YES if the engine coolant is above the calibrated value. A YES indication will disable the Displacement on Demand system.

Deact Inhibit Engine RPM
- This parameter displays YES if the engine RPM is not within the calibrated range. A YES indication will disable the Displacement on Demand system.

Deact Inhibit EOP
- This parameter displays YES if the engine oil pressure is not within the calibrated range. A YES indication will disable the Displacement on Demand system.

Deact Inhibit EOP Sensor DTC
- This parameter will display YES if DTC P0520, P0522, or P0523 is set. A YES indication will disable the Displacement on Demand system.

Deact Inhibit ETC Sensor DTC
- This parameter displays YES if DTC P0116, P0117, or P0118 is set. A YES indication will disable the Displacement on Demand system.

Deact Inhibit Hot Coolant Mode
- This parameter displays YES if the engine control module defaults to the hot coolant mode. The hot coolant mode is calibrated from several different engine control module (ECM) parameters. A YES indication will disable the Displacement on Demand system.

Deact Inhibit Ignition Voltage
- This parameter displays YES if the ignition 1 voltage signal to the engine control module (ECM) is not within the calibrated range. A YES indication will disable the Displacement on Demand system.

Deact Inhibit Low Brake Booster Vacuum
- This parameter displays YES if the brake booster vacuum is below the calibrated value. A YES indication will disable the Displacement on Demand system.

Deact Inhibit Manifold Vacuum Low
- This parameter displays YES if the engine intake manifold vacuum is below a calibrated value. A YES indication will disable the Displacement on Demand system.

Deact Inhibit Map Sensor DTC
- This parameter displays YES if DTC P0106, P0107, or P0108 is set. A YES indication will disable the Displacement on Demand system.

Deact Inhibit Maximum Deactivation Time Exceeded
- This parameter displays YES if the engine has been in V4 mode for 10 minutes. A YES indication will disable the Displacement on Demand system.

Deact Inhibit Minimum Time on All Cylinders
- This parameter displays YES if the minimum engine run time in V8 mode is below a calibrated value. A YES indication will disable the Displacement on Demand system.

Deact Inhibit Oil Aeration
- This parameter displays YES if engine oil aeration is detected. Engine oil aeration is calculated from several different engine parameters. A YES indication will disable the Displacement on Demand system.

Deact Inhibit Piston Protection
- This parameter displays YES if excessive engine knock is detected. A YES indication will disable the Displacement on Demand system.

Deact Inhibit TAC System DTC
- This parameter displays YES if DTC P0068, P0120, P0121, P0122, P0123, P0220, P0223, P0506, P0507, P1516, P2101, P2119, p2120, P2122, P2123, P2125, P2127, P2128, P2135, P2138, or P2176 is set. A YES indication will disable the Displacement on Demand system.

Deact Inhibit Cyl. Deactivation Solenoid DTC
- This parameter displays YES if DTC P3401, P3425, P3441, or P3449 is set. A YES indication will disable the Displacement on Demand system.

Deact Inhibit Torque Reduction
- This parameter displays YES if the engine control module (ECM) determines the delivered torque signal is below the calibrated value. The delivered torque signal is calculated from several different ECM parameters. A YES indication will disable the Displacement on Demand system.

Deact Inhibit Trans Gear
- This parameter displays YES if the transmission is not in the correct gear. A YES indication will disable the Displacement on Demand system.

Deact Inhibit Trans Range
- This parameter displays YES if the transmission gear shift lever is not in the correct position. A YES indication will disable the Displacement on Demand system.

Deact Inhibit Trans Shifting
- This parameter displays YES if a transmission gear change is in progress. A YES indication will disable the Displacement on Demand system.

Deact Inhibit TWC Over Temperature Protection
- This parameter displays YES if catalytic converter overheating is detected. Catalytic converter overheating is calculated from several different engine control module (ECM) parameters. A YES indication will disable the Displacement on Demand system.

Deact Inhibit VSS DTC
- This parameter displays YES if DTC P0608 is set. A YES indication will disable the Displacement on Demand system.

Deact Inhibit VSS Low w/TCC ON
- This parameter displays YES if the vehicle speed sensor signal is below the calibrated value with the torque converter clutch ON. A YES indication will disable the Displacement on Demand system.

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.

Desired IAC Airflow
- This parameter displays the desired airflow in the idle air control (IAC) passage as calculated by the control module.

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

Distance Since DTC Cleared
- This parameter displays the distance accumulated since an emission diagnostic trouble code was cleared. The scan tool will display increasing distance as the vehicle is driven.

Distance with CYL. Activated
- This parameter displays the total distance the vehicle traveled in V8 mode for the current ignition cycle.

Distance with CYL. Deactivated
- This parameter displays the total distance the vehicle traveled in V4 mode for the current ignition cycle.

DTC Set This Ignition
- This parameter displays if a diagnostic trouble code (DTC) set during the current ignition cycle. The scan tool will display YES if a DTC is stored this ignition cycle.