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 given 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 is determined
- The Diagnostic System Check-Engine Controls is completed.
- No diagnostic trouble codes (DTCs)
- 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 values that would be seen on a normal running engine.
| IMPORTANT | A scan tool that displays faulty data should not be used. The scan tool problem should be reported to the manufacturer. Use of a faulty scan tool can result in misdiagnosis and 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 can be located on the scan tool. Refer to 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 |
|---|---|---|---|
| Operating conditions: Engine Idling/Radiator Hose Hot/Closed Throttle/Park or Neutral/Closed Loop/Accessories Off | |||
| 4WD Signal | Eng 2 | Enabled/Disabled | Disabled |
| 4WD Low Signal | Eng 2 | Enabled/Disabled | Disabled |
| A/C Clutch Feedback Signal | Eng 2 | ON/OFF | OFF |
| A/C Compressor Cycling Switch | Eng 2 | Low/High Pressure | Low Pressure |
| A/C High Pressure Recirculation | Eng 2 | Normal/Low | Normal |
| A/C Relay Command | Eng 1, 2, EGR, MF | On/Off | Off |
| A/C Request Signal | Eng 2 | Yes/No | No |
| Air Fuel Ratio | FF, FR | Ratio | 14.7:1 |
| AIR Pump Relay Command (w/NC1) | Eng 1, FT | On/Off | Off |
| BARO | Eng 1, EE, EGR, FT, FF, FR | KPa/volts | 65-104 kPa/3.5-4.9 Volts Varies w/Altitude |
| Clutch Pedal Switch (Manual Transmission only) | Eng 1, 2, EGR | Depressed/Released | Released |
| CMP Retard | Eng 1 | Degrees | 1° |
| CMP Sensor - High to Low | Eng 2 | Counts | Varies |
| CMP Sensor - Low To High | Eng 2 | Counts | Varies |
| Cruise Control Active | Eng 1 | Yes/No | No |
| Cruise Inhibit Signal Command | Eng 1 | ON/OFF | ON |
| Current Gear | Eng 1, 2, EGR, FF, FR, FT | 0-4 | 1 |
| Cycles of Misfire Data | MF | 0-100 Counts | Varies |
| Desired EGR Position | Eng 1, EGR, FF, FR, MF | 0-100% | 0% |
| Desired EGR Position | EGR | 0-5 volts | Less than 1.3 volts |
| Desired IAC Airflow | Eng 1 | 0-64 g/s | Varies |
| Desired IAC Position | Eng 1 | Counts | Varies |
| Desired Idle Speed | Eng 1, 2, EE, FF, FR | RPM | PCM Controlled |
| DTC Set This Ignition | Eng 1, 2, EE, FT | Yes/No | No |
| ECT Sensor | Eng 1, 2, EE, EGR, FT, MF, FF, FR | 39 to +140°C (-38 to +284°F) | 88-105°C (190-221°F) Depends on ambient temperature |
| EGR Learned Minimum Position | EGR | 0-5.0 volts | Less than 1.3 volts |
| EGR Position Sensor | Eng 1, EGR, FF, FR, MF | 0-5.0 volts | Less than 1.3 volts |
| EGR Position Sensor | Eng 1, EGR, MF | 0-100 % | 0 % |
| Engine Load | All | 0-100% | 1-4% @ Idle 7-9% @ 2500 RPM |
| Engine Oil Life Remaining | Eng 2 | 0-100% | Varies |
| Engine Run Time | All | Hrs, Min, Sec | Varies |
| Engine Speed | All | 0-10,000 RPM | 500-700 RPM |
| EVAP Purge Solenoid Command | Eng 1, EE, FT | 0-100% | 10-25% |
| EVAP Vent Solenoid Command | Eng 1, EE, FT | Not Venting/Venting | Venting |
| EVAP Test Abort Reason | EE | Aborted/Not Aborted | Not Aborted |
| EVAP Test Result | EE | Test Result | Varies |
| EVAP Test State | EE | Test State | Varies |
| Fail Counter | FF, FR | Counts | Varies |
| Fuel Level Sensor | EE | 0-5 volts | 0.7-2.5 volts |
| Fuel Tank Level Remaining | EE, FT | Gallon/Liter | Varies |
| Fuel Tank Level Remaining | EE, FT | 0-100% | Varies |
| Fuel Tank Pressure Sensor | Eng 1, EE | 32.7 to +14.0 mm/Hg (-17.5 to +7.5 in/H2O) | Varies |
| Fuel Tank Pressure Sensor | EE | 0-5.0 volts | Varies |
| Fuel Tank Rated Capacity | EE | 98 Liters (25.9 Gallons) or 129 Liters (34 Gallons) | Varies with fuel tank option |
| Fuel Trim Cell | Eng 1, EE, FT | 0-23 | 16, 17 |
| Fuel Trim Learn | Eng 1, EE, FT | Enabled/Disabled | Enabled (may Toggle) |
| Generator F Terminal Signal | Eng 2 | Percent | Varies |
| Generator L Terminal Signal Command | Eng 2 | ON/OFF | ON |
| HO2S Bank 1 Sensor 1 | Eng 1, EE, FT | Millivolts | 10-1,000 mV and Varying |
| HO2S Bank 1 Sensor 2 | Eng 1, FT | Millivolts | 10-1,000 mV and Varying |
| HO2S Bank 2 Sensor 1 | Eng 1, EE, FT | Millivolts | 10-1,000 mV and Varying |
| HO2S Bank 2 Sensor 2 | Eng 1, FT | Millivolts | 10-1,000 mV and Varying |
| IAC Position | Eng 1, EGR, FT | Counts | Varies |
| IAT Sensor | Eng 1, 2, EE, EGR, FT | 39 to +140°C (-38 to +284°F) | 35°C (91°F) Depends on ambient temperature |
| Ignition 1 Signal | Eng 1, 2, EE, EGR, FT | 0-25 volts | 11.5-14.5 Volts |
| Inj. PWM Bank 1 Average | Eng 2, FT, FF, FR, MF | Milliseconds | 2-6 |
| Inj. PWM Bank 2 Average | Eng 2, FT, FF, FR, MF | Milliseconds | 2-6 |
| Knock Retard | Eng 1, EGR | 0.0°-16° | 0° |
| Long Term FT Avg. Bn 1 | FT | Percentage | Near 0% |
| Long Term FT Avg. Bn 2 | FT | Percentage | Near 0% |
| Long Term FT Bank 1 | Eng 1, 2, EE, FT, FF, FR | Percentage | Near 0% |
| Long Term FT Bank 2 | Eng 1, 2, EE, FT, FF, FR | Percentage | Near 0% |
| Loop Status | Eng 1, 2, EE, EGR, FT, FF, FR | Open/Closed | Closed |
| MAF Sensor | All | Grams Per Seconds (g/s) | 1-9 g/s @ Idle (depends on altitude) 15-26 g/s @ 2,500 RPM (depends on altitude) |
| MAF Sensor | Eng 2 | 0-31,999 Hz | 2,000-3,000 Hz |
| MAP Sensor | All | KPa | 20-48 kPa |
| MAP Sensor | Eng 1, 2 | Volts | 1.0-2.0 volts Varies with altitude |
| MIL Command | Eng 2 | Off/On | Off |
| Mileage Since DTC Cleared | Eng 2 | Km/Miles | Varies |
| Misfire Counter Status | MF | Normal/Invalid | Normal |
| Misfire Current Cyl. 1-6 | MF | 0-200 Counts | 0 |
| Misfire History Cyl. 1-6 | MF | 0-65,535 Counts | 0 |
| PCM Reset | Eng 1, 2, EGR, EE, FT | Yes/No | No |
| PCM/VCM in VTD Fail Enable | Eng 1 | Yes/No | No |
| Short Trim FT Avg. Bn1 | FT | Percentage | Near 0% |
| Short Trim FT Avg. Bn2 | FT | Percentage | Near 0% |
| Short Term FT Bank 1 | Eng 1, 2, EE, FT, FF, FR | Percentage | Near 0% |
| Short Term FT Bank 2 | Eng 1, 2, EE, FT, FF, FR | Percentage | Near 0% |
| Spark | Eng 1, 2, FT, MF | Degrees | 15-20° |
| Start Up ECT | Eng 2, EE, FT, FF, FR | C°/F° | Varies |
| Stoplamp Pedal Switch | Eng 1, 2 | Applied/Released | Released |
| Torque Request Signal | Eng 2 | Nm | |
| Torque Request Signal | Eng 2 | Nm | |
| TCC Enable Solenoid Command | Eng 1, 2, MF, FF, FR | ON/OFF | OFF |
| TCC PWM Solenoid Command | Eng 2 | ON/OFF | OFF |
| TP Sensor | Eng 1, 2, EE, FT, MF, EGR, FF, FR | 0-100% | 0% |
| TP Sensor | Eng 1, 2 | 0-5.0 volts | .04-.09 volts |
| TFP Switch | Eng 2, EGR, FT | Transmission Gear Position | Varies |
| TR Switch | Eng 2, EGR, FT | Transmission Gear Position | Varies |
| Vehicle Speed Sensor | All | Km/h mph | 0 |
| VTD Auto Learn Timer | Eng 1, FF, FR | Active/Inactive | Inactive |
| VTD Fuel Disable | Eng 1 | Active/Inactive | Inactive |
| VTD Fuel Disable Until Ign. Off | Eng 1 | Yes/No | No |
| Warm-Ups w/o Emission Faults | Eng 2 | 0-255 Counts | Varies |
| Warm-Ups w/o Non-Emission Faults | Eng 2 | 0-255 Counts | Varies |
Scan Tool Data List
Scan Tool Data Definitions
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.
Scan Tool Output Controls
| Scan Tool Output Control | Additional Menu Selection(s) | Description |
|---|---|---|
| Crankshaft Position Variation Learn | Enables the powertrain control module (PCM) to learn the variations in the crankshaft position (CKP) system. The PCM will learn the variations once the following conditions are met: Engine coolant temperature (ECT) is more than a specified value. All instructions on the scan tool have been completed. The accelerator pedal is smoothly applied until the fuel cut-OFF, as specified on the scan tool, is achieved, and then immediately released. The PCM learns the variation values on the deceleration from fuel cut-OFF. | |
| Cylinder Power Balance | Fuel System | Enables/Disables a cylinder by turning OFF the fuel injector to the cylinder. The fuel injector is normally enabled. The PCM disables the fuel injector when the following conditions are met: All instruction on the scan tool are completed Stabilized engine speed The fuel injector is selected When the Disable is selected the PCM turns the injector OFF for 30 seconds. During this period, the engine operates with a misfire. |
| RPM Control | IAC System | Activates the idle air control (IAC) valve to change engine RPM. The normal commanded state is NONE. To enable the RPM control, all instruction on the scan tool must be completed. The system will INCREASE or DECREASE the RPM within a range of 400-2,000 RPM. The SET STEP VALUE changes the RPM by increments of 25 RPM, 100-500 RPM. The system remains in the commanded state until cancelled by the tool. |
| EVAP Purge Solenoid | Engine Output Controls/EVAP System | Activates the evaporative emission (EVAP) purge valve. The normal commanded state 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 system remains in the commanded state until cancelled by the tool or the fuel tank pressure (FTP) exceeds 32 mm Hg (17 in H20). |
| EVAP Purge/Seal | Engine Output Controls/EVAP System | This control enables two 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 one of the following conditions occurs: Cancelled by the tool The FTP exceeds 32 mm Hg (17 in H20) |
| EVAP Vent Solenoid | Engine Output Controls/EVAP System | 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 until one of the following conditions occurs: Cancelled by the tool Purge is greater than 0 percent, and the fuel tank pressure exceeds 32 mm Hg (17 in H20) |
| Fuel Injector Balance | Fuel System | Enables the fuel injector in order to verify proper fuel injector flow. The PCM will pulse the selected injector when the following conditions are met: All instruction on the scan tool completed Fuel injector selected Key ON, engine OFF The selected fuel injector can only be flowed/pulsed once per ignition cycle. |
| Fuel Pump | Engine Output Controls | Controls the fuel pump relay. The normal commanded state is None. When commanded ON/OFF, the PCM turns the fuel pump ON/OFF. If the engine is running, and the fuel pump is commanded OFF, the engine will stall. The system remains in the commanded state until cancelled by the scan tool. |
| Fuel Trim Enable | Fuel System | Disables the PCMs ability to learn new fuel trim parameters. The system remains in the commanded state until cancelled by the scan tool. |
| Fuel Trim Reset | Fuel System | Activates the reset of fuel trim data in all of the fuel trim cells. |
| Loop Status | Engine Output Controls | Controls the system loop status. The commanded states include None, Open, or Closed. The normal commanded state is None. When commanded Open or Closed, the system remains in the commanded state until cancelled by the scan tool. |
| Malfunction Indicator Lamp | Engine Output Controls | Controls 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 Graph | Graphs the accumulated misfires occurring in each cylinder. The scan tool allows for a reset of the misfire graph. | |
| O2S Heater Control | Engine Output Controls | Activates the HO2S Heater. The commanded states include None, ON, and OFF. The normal commanded state is None. On a cold engine, with the key ON, engine OFF, the HO2S signal will continue to drop below bias when commanded ON. The system remains in the commanded state until cancelled by the tool. |
Scan Tool Output Controls