Diagnostic Starting Point - Engine Controls
Begin the system diagnosis with Diagnostic System Check - Vehicle in Vehicle DTC Information. The Diagnostic System Check - Vehicle will provide the following information
- The identification of the control modules which command the system
- The ability of the control modules to communicate through the serial data circuit
- The identification of any stored DTCs and the codes status
The use of the Diagnostic System Check - Vehicle will identify the correct procedure for diagnosing the system and where the procedure is located.
Scan Tool Data List
The Engine Scan Tool Data List contains all engine related parameters that are available on the scan tool. The list is arranged in alphabetical order. A parameter may appear in any one of the data lists, and in some cases may appear more than once or in more than one data list in order to group certain related parameters together.
Use the Engine Scan Tool Data List only after the following conditions are determined
- The Diagnostic System Check - Vehicle is completed.
- There are no diagnostic trouble codes (DTCs).
- The on-board diagnostics are functioning correctly.
Scan tool values from an engine that is operating correctly may be used for comparison with the engine you are diagnosing. The Engine Scan Tool Data List represents the values that would be seen on a normal operating engine.
| IMPORTANT | Do not use a scan tool that displays faulty data. The scan tool concern should be reported to the manufacturer. Use of a faulty scan tool may result in misdiagnosis and unnecessary parts replacement. |
Only the parameters listed below are referenced in this service information for use in diagnosis. If all values are within the typical range described below, refer to Symptoms - Engine Controls for diagnosis.
The column labeled Data List indicates where a parameter is located on the scan tool. Review the scan tool operating manual for the exact locations of the data lists. The following is a description of each term listed
| Scan Tool Parameter | Data List | Parameter Range/Units | Typical Data Values |
|---|---|---|---|
| Engine Idling/Radiator Hose Hot/Park or Neutral/Closed Loop/Accessories Off | |||
| A/C Relay Circuit Status | ODM | OK/Fault/Indeterminate | OK |
| A/C Relay Command | Eng, MF | On/Off | Off |
| APP Indicated Angle | Eng, Ign, CMP, EVAP, HO2S, FT, TAC, Trans | 0-100% | 0% |
| APP Sensor 1 | TAC | 0.9-4.5 Volts | 1 Volt |
| APP Sensor 2 | TAC | 0.40-2.25 Volts | 0.4 Volt |
| APP Sensor 1 and 2 | TAC | Agree/Disagree | Agree |
| BARO | Eng, Ign, CMP, EVAP, HO2S, IM, FT, MF, TAC | 65-104 kPa (8-16 psi) | Varies with altitude |
| BARO | Eng, TAC, Trans | Volts | Varies |
| Catalytic Converter Protection Active | FT, MF | Yes/No | No |
| Catalyst Monitor Complete This Ignition | IM | Yes/No | Varies |
| Catalyst Monitor Enabled this Ignition | IM | Yes/No | Varies |
| CKP Resync Counter | Ign, MF | Counts | 0 Counts |
| Component Monitor Complete This Ignition | IM | Yes/No | Varies |
| Component Monitor Enable This Ignition | IM | Yes/No | Varies |
| Cruise Control Active | Eng | Yes/No | No |
| Current Gear | Eng, FT, MF | P/N/Reverse/1st-5th | P/N |
| Current Gear Signal | Trans | Valid/Invalid | Valid |
| Cycles of Misfire Data | MF | 0-200 counts | Varies |
| Cylinder 1-6 Injector Circuit Status | ODM | OK/Fault/Indeterminate | OK |
| Cylinder 1-6 Knock Retard | Ign | Degree | 0 Degrees |
| Decel. Fuel Cutoff | Eng, FT, HO2S | Active/Inactive | Inactive |
| Desired Exh. CMP Bank 1 or 2 | CMP | Degree | Varies |
| Desired HO2S 1 | HO2S | Lambda | Varies |
| Desired Idle Speed | Eng, EVAP, CMP, TAC | 0-7,000 RPM | 650 RPM |
| Desired Int. CMP Bank 1 or 2 | CMP | Degrees | Varies |
| DTC Set This Ignition | Eng, Ign, CMP, EVAP, FT, HO2S, TAC | Yes/No | No |
| EC Ignition Relay Command | Eng, TAC | On/Off | On |
| EC Ignition Relay Feedback Signal | Eng, TAC | 0-25.5 Volts | 12.0-14.5 Volts |
| ECM Reset | Eng, Ign, EVAP, FT | Yes/No | No |
| ECT Sensor | Eng, Ign, CMP, EVAP, HO2S, FF, FR, FT, IM, MF, TAC, Trans | 39°C to +140°C (-38°F to +284°F) | Varies |
| Engine Load | Eng, Ign, CMP, EVAP, HO2S, FF, FR, FT, MF, TAC, Trans | 0-99% | 25-45% - Idle 40-60% - 2500 RPM |
| Engine OFF EVAP Test Conditions Met | EVAP | Yes/No | Varies |
| Engine Off Time | EVAP, IM | 0:00:00 Seconds | Varies |
| Engine Oil Level Switch | Eng, CMP | OK/Low | OK |
| Engine Oil Life Remaining | CMP | % | Varies |
| Engine Oil Pressure Sensor | Eng, MF | 1-5 Volts | Varies |
| Engine Oil Pressure Sensor | MF, CMP | KPa/psi | Varies |
| Engine Run Time | Eng, Ign, EVAP, FT, HO2S, IM, MF, TAC, CMP, ODM, Trans | 0:00:00 | Varies |
| Engine Speed | ALL | RPM | 575-700 RPM |
| EVAP Monitor Complete This Ignition | IM | Yes/No | Varies |
| EVAP Monitor Enabled This Ignition | IM | Yes/No | Varies |
| EVAP Purge Solenoid Circuit Status | ODM | OK/Fault/Indeterminate | OK |
| EVAP Purge Solenoid Command | Eng, EVAP, FT | 0-100% | Varies |
| EVAP Vent Solenoid Circuit Status | ODM | OK/Fault/Indeterminate | OK |
| EVAP Vent Solenoid Command | Eng, EVAP, FT | Venting/Not Venting | Venting |
| Exh. CMP Angle Bank 1 or 2 | Eng, CMP | Degrees | Varies |
| Exh. CMP Angle Bank 1 or 2 Variance | CMP | Degrees | Varies |
| Exh. CMP Bank 1 or 2 Command | CMP | 0-99% | Varies |
| Exh. CMP Solenoid Bn. 1 or 2 Circuit Status | ODM | OK/Fault/Indeterminate | OK |
| FC Relay 1 Circuit Status | ODM | OK/Fault/Indeterminate | OK |
| FC Relay 2 and 3 Circuit Status | ODM | OK/Fault/Indeterminate | OK |
| Fuel Level | EVAP | 0-100% | Varies |
| Fuel Level Sensor | EVAP | 0-5 Volts | Varies |
| Fuel Pump Relay Circuit Status | ODM | OK/Fault/Indeterminate | OK |
| Fuel Pump Relay Command | Eng | On/Off | On |
| Fuel Tank Level Remaining | Eng, EVAP, IM, MF | Liter/Gallon | Varies |
| Fuel Tank Pressure Sensor | EVAP | In H2O/mm Hg | Varies |
| Fuel Tank Pressure Sensor | Eng, EVAP | 0-5 Volts | Varies |
| Fuel Tank Rated Capacity | EVAP | Liter/Gallon | 17.8 Gallons (67.3 Liters) |
| Fuel Trim Learn | EVAP, FT, HO2S | Enabled/Disabled | Enabled |
| HO2S 1 | Eng, EVAP, FT, HO2S | Lambda | 1.0 Lambda |
| HO2S 2 | Eng, FT, HO2S | 0-1,006 mV | Varies 400-700 mV |
| HO2S Heater Monitor Complete This Ignition | IM | Yes/No | Varies |
| HO2S Heater Monitor Enabled This Ignition | IM | Yes/No | Varies |
| HO2S 1 or 2 Heater Circuit Status | ODM | OK/Fault/Indeterminate | OK |
| HO2S 1 or 2 Heater Command | HO2S | 0-99% | Varies |
| HO2S/O2S Monitor Complete This Ignition | IM | Yes/No | Varies |
| HO2S/O2S Monitor Enabled This Ignition | IM | Yes/No | Varies |
| HO2S 1 Sensing Element | HO2S | Ohms | 70-90 Ohms Depends on Temperature |
| HO2S 2 Sensing Element | HO2S | Ohms | 20-300 Ohms Depends on Temperature |
| HO2S Sensor 1 Module Signal | HO2S | 1-5 Volts | Varies |
| IAT Sensor | Eng, Ign, EVAP, CMP, FT, FF, FR, HO2S, TAC, Trans | 39° to +140°C (-38° to +284°F) | Varies |
| Ignition 0 Signal | Eng, Ign, EVAP, IM, TAC, Trans | On/Off | On |
| Ignition 1 Signal | Eng, Ign, EVAP, FT, IM, MF, TAC, CMP, Trans | On/Off | On |
| Injector 1-6 Command | FT, MF | Ms | Varies |
| Injector PWM Bank 1 or 2 Average | FT, MF | 0-9 ms | 4.6-5.4 ms |
| Int. CMP Angle Bank 1 or 2 | Eng, CMP | Degrees | Varies |
| Int. CMP Angle Bank 1 or 2 Variance | CMP | Degrees | Varies |
| Int. CMP Bank 1 or 2 Command | CMP | 0-99% | Varies |
| Int. CMP Solenoid Bn. 1 or 2 Circuit Status | ODM | OK/Fault/Indeterminate | OK |
| Knock Retard | Eng, Ign | Degrees | Varies |
| KS 1 or 2 Signal | Ign | Volts | Varies |
| Loop Status Sensor 1 or 2 | Eng, EVAP, FT, HO2S, FF, FR | Open Loop/Closed Loop | Closed Loop |
| LT FT Cruise/Accel. | Eng, EVAP, FT, HO2S | 100% to +100% | 0% |
| LT FT Idle/Decel. | Eng, EVAP, FT, HO2S | 100% to +100% | 0% |
| MAF Sensor | Eng, Ign, FT, HO2S, MF, TAC, CMP, FF, FR, Trans | 0-655 g/s | 3.4-6.3 g/s |
| MAF Sensor | Eng, Ign, EVAP, FT, HO2S, MF, TAC, CMP, Trans | 0-5 Volts | 0.9-1.7 Volts |
| MIL Circuit Status | ODM | OK/Fault/Indeterminate | OK |
| MIL Command | Eng, EVAP, IM, Trans | On/Off | Off |
| Mileage Since DTC Cleared | FF, FR | Km - miles | Varies |
| Mileage Since DTC First Failure | FF, FR | Km - miles | Varies |
| Mileage Since DTC Last Failure | FF, FR | Km - miles | Varies |
| Mileage Since MIL Requested | FF, FR | Km - miles | Varies |
| Misfire Current Cyl. 1-6 | MF | 0-255 Counts | 0 |
| Misfire History Cyl. 1-6 | MF | 0-65,535 Counts | 0 |
| Misfire Monitor Complete This Ignition | IM | Yes/No | Varies |
| Misfire Monitor Enabled This Ignition | IM | Yes/No | Varies |
| Moderate Brake Apply Signal | TAC | Applied/Released | Released |
| PNP Switch | Eng, Trans | Park/Neutral/In Gear | P/N |
| Power Enrichment | Eng, FT, HO2S, MF | Active/Inactive | Inactive |
| PRNDL | Trans | D1, D2, D3, D4, D5, Neutral, Park, Reverse | Park/Neutral |
| Reduced Engine Power | Eng, TAC | Active/Inactive | Inactive |
| Short Term FT | Eng, EVAP, FT, HO2S, FF, FR | 25% to +25% | 3% to +3% |
| Spark | Eng, Ign, FT, HO2S, MF, FF, FR | 20 to +40 Degrees | 2-10 Degrees |
| Starter Relay Circuit Status | ODM | OK/Fault/Indeterminate | OK |
| Start Up ECT | EVAP, FT, HO2S, IM | 39° to +140°C (-38° to +284°F) | Varies |
| Start Up IAT | EVAP, FT, HO2S, IM | 39° to +140°C (-38° to +284°F) | Varies |
| Stoplamp Pedal Switch | Eng, TAC | Applied/Released | Released |
| System Power Mode | EVAP, TAC | Off, Accessory, RAP, Run or Crank Request | Run |
| TAC System Learned Counts | TAC | 0-11 Counts | 0 |
| TCC Brake Pedal Switch | IM, Trans | Applied/Released | Released |
| TCC/Cruise Brake Pedal Switch | Trans | Applied/Released | Released |
| TCC Status | Eng, MF, Trans | Locked/Unlocked | Unlocked |
| TCM Requested Torque | TAC, Trans | N.m/lb ft | Varies |
| TCM Torque Increase | TAC, Trans | Yes/No | Varies |
| TCS Torque Increase | TAC | Yes/No | Varies |
| TCS Torque Reduction Active | TAC, Trans | Yes/No | Varies |
| TCM Torque Reduction Active | TAC | Yes/No | Varies |
| Torque Delivered Signal | FT, TAC | 0-100% | Varies |
| Torque Request Signal | FT, TAC, Trans | 0-100% | 90-98% |
| Total Fuel Trim Average | EVAP, FT, HO2S | 100 to +100% | Varies |
| Total Misfire Count | MF | Counts | 0 |
| TP Desired Angle | Eng, EVAP, TAC | 0-100% | Varies |
| TP Indicated Angle | Eng, Ign, EVAP, FT, HO2S, MF, TAC, CMP, FF, FR, Trans | 0-100% | Varies |
| TP Sensor 1 | TAC | 0-5 Volts | 0.5-0.8 Volts |
| TP Sensor 1 Learned Minimum | TAC | 0-5 Volts | 0-0.6 Volts |
| TP Sensor 2 | TAC | 0-5 Volts | 4.7-4.1 Volts |
| TP Sensor 2 Learned Minimum | TAC | 0-5 Volts | 5-3.7 Volts |
| TP Sensors 1 and 2 | TAC | Agree/Disagree | Agree |
| Traction Control Status | TAC | Active/Inactive | Inactive |
| Transmission Gear Selector Signal | Trans | Valid/Invalid | Valid |
| TWC Temperature Calculated | FT, MF | Temperature | Varies |
| Vehicle Speed Sensor | Eng, Ign, EVAP, FT, HO2S, IM, MF, TAC, CMP, FF, FR, Trans | Km/h mph | Varies |
| Volumetric Efficiency | Eng, Ign, EVAP, FT, HO2S, MF, TAC, CMP, Trans | 0-100% | 5-25% - Idle and at 2,500 RPM |
Scan Tool Data List
Scan Tool Data Definitions
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.
Scan Tool Output Controls
| Scan Tool Output Control | Additional Menu Selection(s) | Description |
|---|---|---|
| Camshaft Actuator | Special Functions/Engine Control Module/CMP Actuator System | This function controls the selected camshaft actuator. The normal commanded state is NONE. The system will increase or decrease the angle of the selected camshaft in 5 degree increments up to 40 crankshaft degrees. The scan tool initiates the test when the following conditions are met: The vehicle speed is 0 km/h (0 mph). The transmission is in Park or Neutral. The engine speed is between 1000-1400 RPM. The system remains in the commanded state until cancelled by the scan tool. |
| Camshaft Actuator Solenoid | Special Functions/Engine Control Module/CMP Actuator System | This function controls the selected camshaft actuator solenoid. The normal commanded state is NONE. When commanded ON/OFF, the ECM turns the camshaft actuator solenoid ON/OFF. The scan tool initiates the test when the following conditions are met: The ignition is ON with the engine OFF. No engine speed is detected. The system remains in the commanded state until cancelled by the scan tool. |
| Cylinder Power Balance | Special Functions/Engine Control Module/Fuel System | IMPORTANT: The Misfire Current and Misfire History parameters may not increment when using this function. This function disables the selected fuel injector. The normal commanded state is None. The scan tool initiates the test when the following conditions are met: The engine is operating and the engine idle is stable. The vehicle speed is 0 km/h (0 mph). There are no DTCs set for the vehicle speed sensor. If the fuel injector was disabled for 30 seconds, fuel injector control is not allowed again on the same fuel injector for 60 seconds. |
| EC Ignition Relay | Special Functions/Engine Control Module/Output Controls | IMPORTANT: The EC Ignition Relay Command parameter may not change states when using this output control. This function controls the engine controls (EC) ignition or powertrain (PT) relay. The normal commanded state is NONE. The scan tool initiates the test when the following conditions are met: The engine is not running. There are no crankshaft/camshaft sensor DTCs set. The vehicle speed is zero. There are no vehicle speed sensor DTCs set. When commanded ON/OFF, the ECM turns the EC ignition relay ON/OFF. The system remains in the commanded state until cancelled by the scan tool or the ECM detects an engine speed. |
| Engine Speed Control | Special Functions/Engine Control Module/TAC System | This function controls the idle speed override in 25 RPM, 100 RPM and 500 RPM increments, from the base idle speed to 1400 RPM. The scan tool initiates the test when the following conditions are met: The transmission is in Park or Neutral. The engine speed is less than 1000 RPM The engine speed will remain in the commanded state until cancelled by the scan tool. |
| EVAP Purge Solenoid | Special Functions/Engine Control Module/Output Controls/EVAP System | IMPORTANT: The EVAP Purge Solenoid Command parameter may not change states when using this output control. This function controls the EVAP purge solenoid valve. The normal commanded state is NONE. The system will Increase or Decrease the amount of purge by changing the duty cycle of the purge valve in 10 percent increments within a range of 0-100 percent. The system remains in the commanded state until cancelled by the scan tool or the fuel tank pressure (FTP) sensor exceeds -24 mm Hg (-12 in H20). |
| EVAP Test | Service Bay Test | This function activates the Service Bay Test to verify the integrity of the EVAP system. The scan tool initiates the test when the following conditions are met: All instructions on the scan tool have been completed. ECT is less than a specified value. No EVAP DTCs are set. |
| EVAP Purge/Seal | Special Functions/Engine Control Module/Output Controls/EVAP System | IMPORTANT: The EVAP Purge and Vent Solenoid Command parameters may not change states when using this output control. This function activates both the EVAP purge solenoid valve and EVAP vent solenoid to seal the EVAP system. When activated, the purge valve is commanded to 0 percent and the vent valve is commanded ON, Not-venting. The normal commanded state for both solenoids is None. Both of the solenoids remain in the commanded state until cancelled by the scan tool or the fuel tank pressure (FTP) sensor exceeds -24 mm Hg (-12 in H20). |
| EVAP Vent Solenoid | Special Functions/Engine Control Module/Output Controls/EVAP System | IMPORTANT: The EVAP Vent Solenoid Command parameter may not change states when using this output control. This function controls the EVAP vent solenoid. The normal commanded state is NONE. When commanded ON, the vent valve switches to Not-venting. The system remains in the commanded state unless one of the following conditions occurs: Cancelled by the scan tool The EVAP canister Purge solenoid is more than 0 percent and the fuel tank pressure (FTP) sensor exceeds -24 mm Hg (-12 in H20). |
| Fuel Injector Balance | Special Functions/Engine Control module/Fuel System | This function enables the fuel injector in order to verify the correct fuel injector flow. The ECM will pulse the selected fuel injector when the following conditions are met: All instruction on the scan tool is complete. A fuel injector is selected. The ignition is ON with the engine OFF. The selected fuel injector can only be flowed/pulsed once per ignition cycle. |
| Fuel Pump | Special Functions/Engine Control Module/Output Controls | This function controls the fuel pump relay. The normal commanded state is NONE. The scan tool initiates the test when the following conditions are met: There are no vehicle speed sensor DTCs set. The vehicle speed is 0 km/h (0 mph). When commanded ON/OFF, the ECM turns the fuel pump relay ON/OFF. If the engine is running and the fuel pump relay is commanded OFF, the engine will stall. The system remains in the commanded state for about 2 seconds or until cancelled by the scan tool or the ECM detects a vehicle speed. |
| Fuel Trim Reset | Special Functions//Engine Control Module/Fuel System | This function resets the fuel trim data and the learned values for the rear heated oxygen sensors. |
| Idle Learn Reset | Special Functions//Engine Control Module/TAC System | This function allows the throttle position and the idle speed to be relearned by the ECM, once the following conditions have been met. The ignition is ON with the engine OFF. The engine coolant temperature is between 5 - 85°C (41 - 185°F). No TAC system DTCs are set. |
| Loop Status | Special Functions//Engine Control Module/Output Controls | This function controls the heated oxygen sensor (HO2S) loop status. The commanded states include NONE, OPEN and CLOSED. The normal commanded state is NONE. The loop status changes as commanded, OPEN or CLOSED. The system remains in the commanded state until cancelled by the scan tool. |
| Malfunction Indicator Lamp | Special Functions//Engine Control Module/Output Controls | This function controls the malfunction indicator lamp (MIL). The normal commanded state is NONE. When commanded ON/OFF, the ECM turns the malfunction indicator lamp (MIL) ON/OFF. The system remains in the commanded state until cancelled by the scan tool. |
| Throttle Blade Control | Special Functions//Engine Control Module/TAC System | This function controls the throttle valve in 10 percent increments. The scan tool initiates the test when the following conditions are met: There are no vehicle speed sensor DTCs set. The vehicle speed is 0 km/h (0 mph). The ignition is ON, with the engine OFF. The ECM is not commanding a throttle learn. The system remains in the commanded state until cancelled by the scan tool. |
| IMPORTANT |
|---|
| The Misfire Current and Misfire History parameters may not increment when using this function. |
| IMPORTANT |
|---|
| The EC Ignition Relay Command parameter may not change states when using this output control. |
| IMPORTANT |
|---|
| The EVAP Purge Solenoid Command parameter may not change states when using this output control. |
| IMPORTANT |
|---|
| The EVAP Purge and Vent Solenoid Command parameters may not change states when using this output control. |
| IMPORTANT |
|---|
| The EVAP Vent Solenoid Command parameter may not change states when using this output control. |
Scan Tool Output Controls