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 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 - Vehicle is completed.
- No 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 |
|---|---|---|---|
| Engine Idling/Radiator Hose Hot/Closed Throttle/Park or Neutral/Closed Loop/Accessories Off | |||
| A/C Relay Command | ED, MF | On/Off | Off |
| A/C Request | MF | Yes/No | No |
| Air Fuel Ratio | ED, FJ, HO2S | Ratio | 14.7:1 |
| APP Indicated Angle | ED, EVAP, FJ, HO2S, ID, MF, TAC | 0-96% | 0% |
| APP Sensor 1 | TAC | %/Volts | 0%/1.02 Volts |
| APP Sensor 2 | TAC | %/Volts | 0%/4.04 Volts |
| APP Sensor 1 and 2 | TAC | Agree/Disagree | Agree |
| APP Sensor 1 Circuit | TAC | ||
| APP Sensor 2 Circuit | TAC | ||
| BARO | ED, EVAP, FT, HO2S, ID | KPa | 65-104 kPa/ Varies w/Altitude |
| Catalytic Converter Protection Active | FT, HO2S | ||
| CKP Active Counter | ID | 1-250 | 9-250 |
| CMP Active Counter | ID | Counts | Varies |
| CMP Sensor | ED, ID, MF | RPM | RPM |
| Cold Start-Up | ED, EVAP | Varies | Varies |
| Crank Request Signal | Eng 3 | Yes/No | No |
| Cruise Control Active | TAC | Yes/No | No |
| Cycles of Misfire Data | MF | 0-100 Counts | Varies |
| Decel Fuel Cutoff | ED, FT, HO2S | ||
| Desired Idle Speed | ED, EVAP, TAC | RPM | PCM Controlled |
| EC Ignition Relay Feedback | ED | Volts | Volts |
| EC Ignition Relay Feedback | TAC | Volts | Volts |
| ECT Sensor | ED, EVAP, FT, HO2S, ID, MF, TAC | 40 to -40°C (+151 to +303°F) | 88-105°C (190-221°F) Depends on ambient temperature |
| Engine OFF Time | EVAP | ||
| Engine Load | ED, EVAP, FT, HO2S, ID, MF, TAC | 0-100% | 23-24% @ Idle 7-42% @ 2500 RPM |
| Engine Oil Pressure Switch | ED, MF | OK/Low | OK |
| Engine Run Time | ED, EVAP, HO2S, ID, MF, TAC | Hrs, Min, Sec | Varies |
| Engine Speed | ED, EVAP, FT, HO2S, ID, MF, TAC | 0-10,000 RPM | 500-700 RPM |
| EVAP Fault History | EVAP | ||
| EVAP Purge Solenoid Command | ED, EVAP, FT | 0-100% | 10-30% |
| EVAP Vent Solenoid Command | ED, EVAP | Not Venting/Venting | Venting |
| Fuel Tank Level Remaining | ED, EVAP, MF | % | % |
| Fuel Tank Pressure Sensor | ED, EVAP | Mm/Hg / In H2O | Varies |
| Fuel Tank Pressure Sensor | EVAP | Mm/Hg / In H2O/Volts | Varies |
| Fuel Trim Cell | ED, EVAP, FT | 0-23 | 16, 17, 21 |
| Fuel Trim Learn | ED, EVAP, FT | ||
| Fuel Level Sensor | EVAP | 0-100% | Varies |
| Fuel Pump Relay Command | ED | On/Off | On |
| HO2S 1 | ED, EVAP, FT, HO2S | MV | 10-1,000 mV and Varying |
| HO2S 2 | ED, FT, HO2S | MV | 10-1,000 mV and Varying |
| HO2S 1 Heater Current | HO2S | Amps | Varies |
| HO2S 2 Heater Current | HO2S | Amps | Varies |
| Hot Open Loop | FT, HO2S | ||
| IAT Sensor | ED, EVAP, FT, ID, MF | 40 to +151°C (-40 to +303°F) | Depends on ambient temperature |
| Ignition 1 Signal | ED, EVAP, FT, HO2S, ID, MF, TAC | 0-25 volts | 11.5-14.5 Volts |
| Initial Brake Apply Signal | TAC | ON/OFF | ON/OFF |
| Initial Brake Supply Signal | ED | ||
| Injector PWM | FT, MF | Milliseconds | 2-6 ms |
| Knock Retard | ID | ° | ° |
| Long Term FT | ED, EVAP, FT, HO2S | % | Near 0% |
| Long Term FT Avg | FT | % | % |
| Loop Status | ED, EVAP, FT, HO2S | Open/Closed | Closed |
| MAF Sensor | EVAP, FT, HO2S, MF | Hz | Hz |
| MAF Sensor | ED, EVAP, FT, HO2S, ID, MF, TAC | G/s | Varies |
| MAP Sensor | ED, EVAP, FT, HO2S, ID, MF, TAC | KPa | 20-48 kPa |
| Medium Resolution Resync Counter | ID | Counts | 0 |
| MIL Command | ED, EVAP, ID | Off/On | Off |
| MIL Requested By DTC | ED, EVAP, ID | ||
| Mileage Since DTC Clear | ED | M/Km | M/Km |
| Misfire Current Cyl #1 | MF | Varies | 0 |
| Misfire Current Cyl #2 | MF | Varies | 0 |
| Misfire Current Cyl #3 | MF | Varies | 0 |
| Misfire Current Cyl #4 | MF | Varies | 0 |
| Misfire History Cyl #1 | MF | Varies | 0 |
| Misfire History Cyl #2 | MF | Varies | 0 |
| Misfire History Cyl #3 | MF | Varies | 0 |
| Misfire History Cyl #4 | MF | Varies | 0 |
| PCM Reset | ED, EVAP, ID | ||
| Power Enrichment | ED, FT, HO2S, MF | Active/Inactive | Inactive |
| Reduced Engine Power | TAC | Active/Inactive | Inactive |
| Reference Voltage 1 Signal | ED, EVAP, ID, TAC | Volts | 5.03 V |
| Reference Voltage 2 Signal | ED, EVAP, ID, TAC | Volts | Volts |
| Short Term FT | ED, EVAP, FT, HO2S | % | Near 0% |
| Short Term FT Avg | FT | % | % |
| Spark | ED, FT, HO2S, ID, MF | Degrees | 11-20° |
| Start Up ECT | EVAP, FT | °C/°F | Varies |
| Start Up IAT | EVAP, FT, HO2S | °C | °C |
| Stop Cam Pedal Switch | TAC | ON/OFF | ON/OFF |
| Total Misfire Count | MF | ||
| TP Desired Angle | TAC | % | 4.2% |
| TP Sensor Learned Minimum | TAC | Volts | Volts |
| Torque Request Signal | TAC | N.m | Varies |
| Torque Delivered Signal | TAC | N.m | Varies |
| TP Indicated Angle | ED, EVAP, FT, HO2S, ID, MF, TAC | % | 4.2% |
| TP Sensors 1 and 2 | TAC | Agree/Disagree | Agree |
| TP Sensor 1 | TAC | 0-100% | 4% |
| TP Sensor 2 | TAC | 0-100% | 4% |
| TP Sensor 1 | TAC | 0-5.0 volts | 4.24 volts |
| TP Sensor 2 | TAC | 0-5.0 volts | 0.78 volts |
| Traction Control Status | TAC | Active/Inactive | Inactive |
| TWC Temperature Calculated | MF | C/F | 350°C |
| Vehicle Speed Sensor | ED, EVAP, HO2S, ID, MF, TAC | Km/h mph | 0 |
| Warm-ups w/o Non-Emmisons Faults | ED | ||
| Warm-ups w/o Emmisons Faults | ED | ||
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 |
|---|---|---|
| EVAP Purge Solenoid (PWM) | 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 percent to 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 H2O). |
| 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 Closed (not venting). The normal commanded state of both valves is NONE. The system will INCREASE or DECREASE the amount of evaporative emission (EVAP) purge valve opening by 10 percent increments within a range of 0 percent to 100 percent. The second function seals the system after using the purge function to obtain a specific amount of fuel tank pressure. When activated the purge valve is commanded to 0 percent and the vent valve is commanded Closed (not venting). Both functions remain in the commanded state until cancelled by the tool or the fuel tank pressure exceeds 24 mm Hg (12 in H2O). |
| 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 not 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 fuel tank pressure exceeds 24 mm Hg (12 in H2O) |
| 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. |
| Gen L-Terminal | Engine Output Controls | Controls system voltage. Command states include NONE, ON, and OFF. When commanded ON, normal system voltage output is present. When commanded OFF, system voltage output is no longer present, Ignition 1 signal continues to drop, Gen L-Terminal goes to OFF and Gen F-Terminal continues to drop. |
| 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. |
| Front O2 Sensor Heater | Engine Output Controls | Activates the following heated oxygen sensor (HO2S) heater: HO2S sensor 1 The commanded states include NONE, ON and OFF. Commanding O2S heater driver 1 ON turns ON heater driver 1. |
| Rear O2 Sensor Heater | Engine Output Controls | Activates the following heated oxygen sensor (HO2S) heater: HO2S sensor 2 The commanded states include NONE, ON and OFF. Commanding O2S heater driver 2 ON turns ON heater driver 2. |
Scan Tool Output Controls