Diagnostic Starting Point - Engine Controls
Begin the system diagnosis with Diagnostic System Check - Vehicle . 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 diagnostic trouble codes (DTCs) and the codes' statuses
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 properly.
Scan tool values from a properly running engine 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 running 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 can result in misdiagnosis and in unnecessary parts replacement. |
Only the parameters listed below are referenced in this service manual 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 | OK |
| A/C Relay Command | Eng 1, MF | On/Off | Off |
| APP Indicated Angle | CMP, EVAP, HO2S, Ign, TAC, FT | 0-99% | 0 percent at idle |
| APP Sensor 1 | TAC | 0.9-4.5 Volts | 1 Volt |
| APP Sensor 1 | TAC | % | 2% |
| APP Sensor 2 | TAC | 0.45-2.25 Volts | 0.5 Volt |
| APP Sensor 2 | TAC | % | 2% |
| APP Sensor 1 and 2 | TAC | Agree/Disagree | Agree |
| Baro | Eng 1, EVAP, FT, HO2S, Ign | 65-104 kPa -16 psi | Varies with altitude |
| Catalytic Converter Protection Active | FT, HO2S | Yes/No | No |
| Commanded Gear | Eng 1, FT, MF | P/N/R/1-5 | P/N |
| Cruise Control Active | Eng 1, TAC | Active/Inactive | Inactive |
| Current Gear Signal | Eng 1, FT | Valid/Invalid | Valid |
| Cycles of Misfire Data | MF | 0-9999 | 0 |
| Cylinder 1-8 IC Circuit Status | ODM | Fault/OK | OK |
| Cylinder 1-8 Injector Circuit Status | ODM | Fault/OK | OK |
| Cylinder 1-8 Knock Retard | Ign | Degrees | 0 |
| Decel. Fuel Cutoff | Eng 1, FT, HO2S | Active/Inactive | Inactive |
| Desired Exhaust CMP Bn 1 or Bn 2 | CMP | Degrees | 0 |
| Desired HO2S Bank 1 or Bank 2 Sensor 1 | FT, HO2S | Lambda | Varies |
| Desired Idle Speed | CMP, Eng 1, EVAP, TAC | 0-7,000 RPM | 650 RPM |
| Desired Intake CMP Bn 1 or Bn 2 | CMP | Degrees | 0 |
| Desired Ignition Spark | Ign | 0-100% | 68% |
| Desired Torque | Ign, FT | N.m | 45-55 |
| EC Ignition Relay Command | Eng 1, TAC | On/Off | On |
| EC Ignition Relay Feedback Signal | Eng 1, TAC | Volts | 13.5 V |
| ECM Reset | Eng 1, EVAP, FT, Ign, ODM | Yes/NO | No |
| ECT Sensor | CMP, Eng 1, EVAP, FT, Ign 1, HO2S, MF, TAC | 39 to +140°C/-38 to +284°F | 85-105°C/185-220°F |
| Engine Load | CMP, Eng 1, EVAP, FT, HO2S, Ign, MF, TAC | 0-99% | 2% |
| Engine Off EVAP Test Conditions Met | EVAP | Yes/No | No |
| Engine Off EVAP Test Ran Last Ignition Cycle | EVAP | Yes/No | No |
| Engine Off Time | EVAP | Seconds | 0 |
| Engine Oil Level Switch | Eng 1, CMP | OK/Low | OK |
| Engine Oil Life Remaining | CMP | % | Varies |
| Engine Oil Pressure Sensor | CMP, Eng1, MF | KPa | 180 kPa |
| Engine Oil Temperature | CMP | °C/°F | 95°C |
| Engine Run Time | CMP, Eng 1, EVAP, FT, HO2S, Ign, MF, TAC | 0:00:00 | Varies |
| Engine Speed | CMP, Eng 1, EVAP, FT, HO2S, Ign, MF, TAC | RPM | 650 RPM |
| Engine Torque | Ign, FT | N.m | 45-55 |
| EVAP Fault History | EVAP | Fault/No Fault | No Fault |
| EVAP Purge Solenoid Command | Eng 1, EVAP, FT, HO2S | 0-100% | Varies |
| EVAP Purge Solenoid Circuit Status | ODM | Fault/OK | OK |
| EVAP Vent Solenoid Command | Eng 1, EVAP, FT | On/Off | Off |
| EVAP Vent Solenoid Circuit Status | ODM | Fault/OK | OK |
| EVAP Test Abort Reason | EVAP | Aborted/Not Aborted | Not Aborted |
| EVAP Test Result | EVAP | No Result | No Result |
| EVAP Test State | EVAP | Purge/wait for purge | Wait for purge |
| Exh. CMP Angle Bank 1 or Bank 2 | CMP, Eng 1, Ign | Degrees | 0 |
| FC Relay 1 Circuit Status | ODM | Fault/OK | OK |
| FC Relay 2 Circuit Status | ODM | Fault/OK | OK |
| FC Relay 1 Command | Eng 1 | ON/OFF | ON |
| FC Relay 2 Command | Eng 1 | ON/OFF | ON |
| Fuel Level Sensor Left Tank | EVAP | 0-5 Volts | Varies |
| Fuel Level Sensor Right Tank | EVAP | 0-5 Volts | Varies |
| Fuel Pump Command | Eng 1 | On/Off | On |
| Fuel Pump Relay Circuit Status | ODM | Fault/OK | OK |
| Fuel Tank Level Remaining | Eng 1, EVAP, MF | Gal/L | Varies |
| Fuel Tank Pressure | EVAP | Volts | 0-5 Volts |
| Fuel Tank Pressure Sensor | Eng 1, EVAP | In H2O/mm Hg | Varies |
| Fuel Tank Rated Capacity | EVAP | Liters/Gal | Varies |
| Fuel Trim Cell | Eng 1, EVAP, FT | Varies | 2 |
| Fuel Trim Learn | Eng 1, EVAP, FT | Enabled/Disabled | Enabled |
| Fuel Volatility | EVAP, FT | Low/High | Low |
| Gen L Terminal Signal Command | Eng 1 | On/Off | On |
| HO2S Bank 1 or Bank 2 Sensor 1 | Eng 1, EVAP, FT, HO2S | Lambda | Varies |
| HO2S Bank 1 or Bank 2 Sensor 2 | Eng 1, FT, HO2S | 0-4,998 mV | Varies 400-800 mV |
| HO2S Heater Bn. 1 or Bn. 2 Sen. 1 | FT, HO2S | 0-99% | Varies |
| HO2S Heater Bn. 1 or Bn. 2 Sen. 2 | FT, HO2S | 0-99% | Varies |
| Hot Open Loop | HO2S, FT | Active/Inactive | Inactive |
| IAT Sensor | CMP, Eng 1, EVAP, FT, HO2S, Ign, TAC | 39 to +140°C/-38 to +284°F | Varies |
| Ignition 0 Signal | Eng 1, TAC | ON/OFF | ON |
| Ignition 1 Signal | CMP, Eng 1, EVAP, FT, HO2S, Ign, MF, TAC | 0-25.5 Volts | 12.8-14.2 Volts |
| Ignition Spark Efficiency | Ign | 0-100% | Varies |
| Initial Brake Apply Signal | Eng 1, TAC | Applied/Released | Released |
| Injector Bn. 1 or Bn. 2 PWM Average | Eng 1, FT, HO2S, Ign, MF | 0-9 ms | 3.0-5.4 ms |
| Injector 1-8 Command | FT, MF | MS | Varies |
| Instant FT Bank 1 or Bank 2 | FT | % | Varies |
| Int CMP Angle Bank 1 or Bank 2 Signal | Eng 1, Ign | Degrees | 0 |
| Int CMP angle Bank 1 or Bank 2 Command | CMP | 0-100% | 7% |
| Integral FT Bank 1 or Bank 2 | FT | % | Varies |
| Knock Retard | Eng1, Ign | 0-191 Degrees | 0 |
| Long Term FT Bank 1 or Bank. 2 | Eng 1, EVAP, FT, HO2S | 100 to +100% | 9% |
| LT FT High RPM/Load Bn. 1 or Bn. 2 | FT | 100 to +100% | 50% |
| LT FT Low RPM/Load Bn. 1 or Bn. 2 | FT | Mg | 255 |
| Loop Status | Eng 1, EVAP, FT, HO2S | Open/Closed | Closed |
| MAF Sensor | CMP, Eng 1, EVAP, HO2S, Ign, MF, TAC, FT | 0-655 g/s | 3-7 g/s |
| MAF Sensor | CMP, Eng 1, EVAP, HO2S, MF, TAC | 0-9999 Hz | 28 Hz |
| MAP Sensor | CMP, Eng 1, EVAP, FT, HO2S, Ign, MF, TAC, FT | KPa/psi | 33 |
| MIL Circuit Status | ODM | Fault/OK | OK |
| MIL Command | Eng 1, Ign | On/Off | Off |
| MIL Requested by DTC | Eng 1, Ign | Yes/No | No |
| Mileage Since DTC Cleared | Eng 1 | Km/mi | Varies |
| Misfire Detects Rough Road | MF | Yes/No | No |
| Misfire History Cyl. 1-8 | MF | 0-255 Counts | 0 |
| Moderate Brake Apply Signal | Eng 1, TAC | Applied/Released | Released |
| PNP Switch | Eng 1 | In Gear/Park/Neutral | Park/Neutral |
| Power Enrichment | Eng 1, FT, HO2S, MF | Active/Inactive | Inactive |
| Reduced Engine Power | Eng 1, TAC | Active/Inactive | Inactive |
| Reference Voltage 1 Signal | Eng 1, Ign, TAC | 0-5 Volts | 5 V |
| Reference Voltage 2 Signal | Eng 1, Ign, TAC | 0-5 Volts | 5 V |
| Short Term FT Bank 1 or Bank 2 | Eng 1, EVAP, FT, HO2S | 100 to +100% | 3% to +3% |
| Spark | Eng 1, FT, HO2S, Ign, MF | 133 to +78 Degrees | 2-5 Degrees |
| Start Up ECT | EVAP, FT, HO2S | 39 to +140°C/-38 to +284°F | Varies |
| Start Up IAT | EVAP, FT, HO2S | 39 to +140°C/-38 to +284°F | Varies |
| Starter Relay Circuit Status | ODM | OK/Fault | OK |
| Starter Relay Command | Eng 1 | On/Off | Off |
| Stoplamp Pedal Switch | Eng 1, TAC | Applied/Released | Released |
| TAC Motor Command | TAC | % | 12-26% |
| TAC Direction | TAC | Closed/Open | Closed |
| TCS Control Signal | TAC | None/Reduced | None |
| Torque Request Signal | TAC | Valid/Invalid | Valid |
| Total Misfire Count | MF | 0-9999 | 0 |
| TP Sensor 1 Learned Min | TAC | 0-5 Volts | 0-0.5 Volts |
| TP Sensor 2 Learned Min | TAC | 5-0 Volts | 5-3.7 Volts |
| TP Desired Angle | Eng 1, EVAP, TAC | 0-99% | Varies |
| TP Indicated Angle | CMP, Eng 1, EVAP, FT, HO2S, Ign, MF, TAC | 0-99% | 2 percent |
| TP Learned | TAC | Yes/No | No |
| TP Learn Enables | TAC | Yes/No | No |
| TP Learn Required | TAC | Yes/No | No |
| TP Sensor 1 | TAC | 0-5 Volts | 0.5-0.8 Volts |
| TP Sensor 1 | TAC | % | 1 |
| TP Sensors 1 and 2 | TAC | Agree/Disagree | Agree |
| TP Sensor 2 | TAC | 0-5 Volts | 4.1-4.5 Volts |
| TP Sensor 2 | TAC | % | 1 |
| Transmission Gear Selector Signal | Eng 1 | Valid/Invalid | Valid |
| TWC Temperature Calculated | FT, MF | C/F | Varies |
| Vehicle Security Status | Eng 1 | Fuel Continue/Fuel Disable | Fuel Continue |
| Vehicle Speed Sensor | CMP, Eng 1, EVAP, FT, HO2S, Ign, MF, TAC | Km/mi | 0 |
| VTD Password Learn Enabled | Eng 1 | Yes/No | No |
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 |
|---|---|---|
| Crankshaft Position Variation Learn | This function allows the control module to learn the variations in the crankshaft position system. The control module will learn the variations once the following conditions are met: The engine coolant temperature is more than a specified value. All instructions on the scan tool are complete. | |
| Cylinder Power Balance | Fuel System | This function allows the control module to turn off individual fuel injectors. The fuel injector is normally enabled. The control module will disable the fuel injector under the following conditions: All instructions on the scan tool are completed. Engine speed is stable. A fuel injector is selected by the technician on the scan tool. When the DISABLE is selected the control module will turn OFF the fuel injector for up to 30 seconds, or until commanded ENABLE with the can tool. |
| Engine Controls Ignition Relay | Output Controls | This function activates the engine control ignition relay. The normal commanded state is NONE. When commanded ON or OFF, the engine control module (ECM) turns the relay ON or OFF. The system remains in the commanded state until cancelled by the scan tool. |
| Engine Speed Control | TAC System | This function activates the throttle actuator control (TAC) system to change engine speed. The normal commanded state is NONE. Follow the scan tool instructions to enable RPM control. The system will increase or decrease the engine speed between 500 RPM and 2,000 RPM. The increments are 25, 100, and 500 RPM. The system remains in the commanded state until cancelled by the scan tool. |
| EVAP Purge Solenoid (PWM) | Output Controls/EVAP System | This function activates the evaporative emission (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 tool or the fuel tank pressure (FTP) exceeds -24 mm Hg (-12 in H20). |
| EVAP Purge/Seal | Output Controls/EVAP System | This function activates 2 functions. One function increases or decreases the amount of purge by changing the duty cycle of the purge valve and commanding the vent ON, non-venting. The normal commanded state of both valves is NONE. The system will INCREASE or DECREASE the amount of EVAP purge valve opening by 10 percent increments within a range of 0-100 percent. The second function seals the system after using the purge function to obtain a specific amount of FTP. When activated, the purge valve is commanded to 0 percent and the vent valve is commanded ON, non-venting. Both functions remain in the commanded state until cancelled by the tool or the FTP exceeds -24 mm Hg (-12 in H20). |
| EVAP Vent Solenoid | Output Controls/EVAP System | This function activates the EVAP vent solenoid. The normal commanded state is NONE. When commanded ON, the vent valve switches to non-venting. The system remains in the commanded state unless one of the following conditions occurs: Cancelled by the tool Purge is greater than 0 percent, and the FTP exceeds -24 mm Hg (-12 in H20) |
| Exhaust CMP Actuator | CMP Actuator System | This function controls the exhaust camshaft position (CMP) actuator. The normal commanded state is 0 degrees. The system will INCREASE or DECREASE the exhaust camshaft timing by changing the duty cycle of the actuator in 5-degree increments up to 50 degrees. This also affects Desired Exh.CMP Angle Bank 1 and Bank 2. |
| Fuel Pump Relay | Output Controls | This function activates the fuel pump relay. The normal commanded state is NONE. 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 until cancelled by the scan tool. |
| Fuel Trim Reset | Fuel System | This function activates the reset of fuel trim data in all fuel trim cells. |
| Intake CMP Actuator | CMP Actuator System | This function controls the intake CMP actuator. The normal commanded state is 0 degrees. The system will INCREASE or DECREASE the intake camshaft timing by changing the duty cycle of the actuator in 5 degree increments up to 40 degrees. This also affects Desired Int. CMP Angle Bank 1 and Bank 2. |
| Malfunction Indicator Lamp (MIL) | Output Controls | This function activates the malfunction indicator lamp (MIL). The commanded states include NONE, ON and OFF. When commanded ON or OFF, the system remains in the commanded state until cancelled by the scan tool. |
| Misfire Graphic | This function graphs the accumulation of misfires occurring in each cylinder. The system remains in the commanded state until cancelled by the scan tool. | |
| O2S Heater Driver 1-4 | Output Controls/Heated Oxygen Sensors | This function activates the oxygen sensor heater. The normal commanded state is NONE. The system will INCREASE or DECREASE the amount of current in 10 percent increments within a range of 0-100 percent. The system remains in the commanded state until cancelled by the tool. |
| Loop Status | Output Controls | This function changes to loop status. The commanded states include Open and Closed. When commanded Open or Closed, the system remains in the commanded state until cancelled by the scan tool. |
| Reset Idle Learn | TAC System | This functions allows the idle speed to be relearned by the control module. |
| Spark Retard | Spark Control | This function control the amount of spark retard by the control module. The normal commanded state is NONE. The System will increase or Decrease the amount of spark retard from 1-10 degrees maximum retard. The system will remain in the commanded state until cancelled by the scan tool. |
| Throttle Position | Output Controls/TAC System | This function opens the throttle plate in 25 percent increments. The scan tool initiates the test when the following conditions are met: The ignition is ON, with the engine OFF. The vehicle speed is 0 km/h mph. The system remains in the commanded state until cancelled by the scan tool. |
Scan Tool Output Controls