Engine Control Module Scan Tool Information (LMU)
The Engine Control Module Scan Tool Data List contains all engine-related parameters that are available on the scan tool. This is a master list arranged in alphabetical order and not all the parameters listed are in every engine platform.
Use the Engine Scan Tool Data List only after the following is determined:
- The Diagnostic System Check - Vehicle is completed.
- No diagnostic trouble codes (DTCs)
- On-board diagnostics are functioning properly
The 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 normally running engine.
IMPORTANT:
A scan tool that displays faulty data should not be used. The scan tool concern 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.
Engine Control Module Scan Tool Data
| Parameter | System State | Expected Value | Description |
|---|---|---|---|
| Base Operating Conditions: Engine Idling/Radiator Hose Hot/Park or Neutral/Closed Loop | |||
| Actual Main Throttle Idle Actuator | - | Steps | This parameter displays the engine control module (ECM) command for the throttle plate position in steps. The higher the number of steps, the greater the commanded opening of the throttle plate. |
| A/C High Side Pressure | A/C OFF | 0-5 Volts | This parameter displays the voltage from the A/C high side pressure sensor signal circuit to the control module. |
| A/C ON | 0-5 Volts | ||
| A/C High Side Pressure | A/C OFF | 500-2,200 kPa (72-319 psi) | This parameter displays the pressure from the A/C high side pressure sensor signal circuit to the control module. |
| A/C ON | 300-1,200 kPa (43-174 psi) | ||
| A/C Relay Command | A/C ON | On | This parameter displays the state of the air conditioning (A/C) clutch relay control circuit as commanded by the control module. |
| BARO | - | 65-104 kPa (8-16 psi) - Varies with altitude | This parameter displays the barometric pressure. The control module uses the barometric pressure sensor input for fuel control to compensate for altitude differences. |
| Desired Idle Speed | - | 800 RPM | This parameter displays the desired engine idle speed as commanded by the control module. |
| Desired Main Throttle Idle Actuator | - | Steps | This parameter displays the desired throttle plate position as commanded by the control module. |
| DTC Set This Ignition | - | No | This parameter displays Yes if a DTC set on the current ignition cycle. |
| ECT Sensor | - | 0-5 Volts | This parameter displays the voltage of the engine coolant based on input to the control module from the engine coolant temperature (ECT) sensor. |
| ECT Sensor | - | -40° to +130°C (-40° to +266°F) | This parameter displays the temperature of the engine coolant based on input to the control module from the engine coolant temperature (ECT) sensor. |
| EC Ignition Relay Command | Ignition ON | ON | This parameter displays the state of the control circuit for main relay as commanded by the control module. |
| EGR Position Sensor | - | 0.6-0.75 Volts | This parameter displays the actual EGR pintle position in volts. |
| EGR Solenoid Command | - | 0% | This parameter displays the state of the control circuit for EGR solenoid as commanded by the control module. |
| Engine Load | Engine Idling | 20-30% | This parameter displays the calculated engine load in percent based on inputs to the control module from various engine sensors. |
| Engine speed at 2,500 RPM | 10-20% | ||
| Engine Speed | Engine Cranking | Greater than 60 RPM | This parameter displays the speed of the engine crankshaft rotation from information received from the crankshaft position (CKP) sensor. If there is a CKP sensor DTC, the ECM calculates the engine speed from one of the camshaft position (CMP) sensors. |
| Engine Idling | Approximately 650-900 RPM | ||
| Engine Running State | - | Idling | This parameter displays the state of the engine. |
| Engine Run Time | - | 0:00:00 Increments when the engine is running | This parameter displays the time elapsed since the engine was started. |
| EVAP Purge Solenoid Command | - | 0-100% | This parameter displays the on-time or duty cycle of the EVAP canister purge solenoid commanded by the control module. Zero percent indicates no purge. One hundred percent indicates full purge. |
| FC Relay 1 Command | Fan Low Commanded ON | ON | This parameter displays the control module commanded state of the fan relay control circuit. |
| FC Relay 2 Command | Fan High Commanded ON | ON | This parameter displays the control module commanded state of the fan relay control circuit. |
| Fuel Gage Control | - | 0-100% | This parameter displays control module commanded state of the fuel gage control circuit. |
| Fuel Level Sensor | - | 0-100% | This parameter displays the amount of fuel in the fuel tank in percent of range, as calculated by the control module. |
| Fuel Level Sensor | - | 0-5 Volts | This parameter displays the voltage signal received by the control module from the fuel level sensor. |
| Fuel Pump Relay Command | Ignition ON, engine OFF | Fuel pump on for 2 seconds | This parameter displays the control modules commanded state of the fuel pump relay control circuit. |
| Engine idling | On | ||
| Fuel Tank Pressure Sensor | - | 0-5 Volts | This parameter displays the voltage signal received by the control module from the fuel tank pressure (FTP) sensor. |
| Fuel Tank Pressure Sensor | - | kPa/PSI | This parameter displays the pressure/vacuum inside the fuel tank. A negative value indicates a vacuum, while a positive value indicates a pressure. |
| HO2S 1 or 2 | - | Varies 400-800 mV | This parameter displays the voltage output from the H/O2S to the control module. A lower voltage indicates a lean exhaust, while a higher voltage indicates a rich exhaust. |
| HO2S 1 and 2 Heater Command | - | 0-100% | This parameter displays the commanded state of the heater control circuit as commanded by the control module. |
| IAT Sensor | - | -39° to +140°C (-38° to +284°F) |
This parameter displays the temperature of the air entering the air induction system based on input to the control module from the intake air temperature (IAT) sensor. |
| IAT Sensor | - | 0-5 Volts | This parameter displays the IAT sensor voltage. |
| Ignition 1 Signal | - | Volts | This parameter displays B+ when the control module detects a voltage at the ignition 1 input terminal. |
| Injector PWM Average | - | 0-9 ms | This parameter displays the average pulse width of the fuel injectors as determined by the control module. |
| Intake Manifold Runner Control (IMRC) Solenoid | - | Open | This parameter displays the control modules commanded state of the IMT Valve solenoid. |
| ISC Actuator | - | 0-100% | This parameter displays the ECM command for the idle speed control (ISC) motor position in percentage. The higher the number, the greater the commanded idle speed reads. The ISC responds to changes in the engine load in order to maintain the desired idle speed. |
| Knock Sensor | - | 0-5 Volts | This parameters displays the voltage input to the control module from the knock sensor (KS). |
| Long Term FT | - | 0% | This parameter displays the commanded Long Term Fuel Trim correction by the control module. |
| Long Term FT Part Throttle | - | 0% | This parameter displays the commanded Long Term Fuel Trim correction by the control module for part throttle conditions. |
| Long Term FT Idle | - | 0% | This parameter displays the commanded Long Term Fuel Trim correction by the control module for idle conditions. |
| Loop Status | - | Closed Loop | This parameter displays the state of the fuel control system as commanded by the control module. Closed Loop operation indicates that the control module is controlling the fuel delivery based off the oxygen sensors input signal. In Open Loop operation the control module ignores the oxygen sensor input signal and bases the amount of fuel to be delivered on other sensor inputs. |
| MAP Sensor | - | 32-40 kPa | This parameter displays the pressure from the MAP sensor to the control module. |
| MAP Sensor | - | 0-5 Volts | This parameter displays the signal voltage from the MAP sensor to the control module. |
| MIL Command | - | Off | This parameter displays the commanded state of the malfunction indicator lamp (MIL) control circuit by the control module. |
| PNP Switch | - | Park/Neutral | This parameter displays whether the transmission range selector is in park/neutral or in gear. |
| Rear Wheel Speed Sensor | - | 0-5 Volts | This parameter displays the speed of the vehicle as calculated by the control module from information received from the vehicle speed sensor (VSS) or wheel speed sensor depending on application. |
| Right Rear Wheel Speed Sensor | - | Km/h mph |
This parameter displays the speed of the vehicle as calculated by the control module from information received from the right rear wheel speed sensor. |
| Short Term FT | - | -3% to +3% | This parameter displays the short-term correction to the fuel delivery by the control module in response to oxygen sensor. If the oxygen sensor indicates a lean air/fuel mixture, the control module will add fuel increasing the short term fuel trim above 0. If the oxygen sensor indicates a rich air/fuel mixture, the control module will reduce fuel decreasing the short term fuel trim below 0. |
| Spark | - | -20 to +40 Degrees | This parameter displays the amount of spark advance the control module is commanding on the ignition control circuits. The control module determines the desired advance. |
| TP Sensor | - | 4.0-4.5 Volts | This parameter displays the actual voltage on the TP sensor signal circuit as measured by the control module. |
| TP Sensor | - | 3-5% | This parameter displays the percent of throttle opening as calculated by the control module using information from the throttle position (TP) sensor. |
| Transmission Gear Selector Signal | - | Park/Neutral | This parameter displays the position of the transmission gear selector that is transmitted over the serial data circuit from the transmission control module (TCM). |
| Vehicle Speed Sensor | - | Km/h mph |
This parameter displays the speed of the vehicle as calculated by the transmission control module (TCM) from information received from the vehicle speed sensor (VSS). |
Engine Control Module (ECM) Scan Tool Output Controls
| Output Control | Description |
|---|---|
| A/C Relay | This function controls the A/C compressor relay. When commanded ON, the A/C compressor will cycle ON/OFF for 3-5 seconds. |
| EGR Solenoid |
IMPORTANT:
This function is only allowed with the ignition ON, engine OFF. This function controls the exhaust gas recirculation (EGR) solenoid. When commanded ON, the EGR solenoid will cycle from 0-100 percent for 3-5 seconds. This output can also be monitored on the scan tool by observing the EGR Position Sensor data parameter. |
| Engine Controls Ignition Relay |
IMPORTANT:
This function is only allowed with the ignition ON, engine OFF. This function controls the engine control ignition relay or MAIN relay. When commanded ON, the engine control ignition relay will cycle ON/OFF for 3-5 seconds. |
| EVAP Purge Solenoid | This function controls the evaporative emission (EVAP) purge solenoid. When commanded ON, the EVAP purge solenoid will cycle ON/OFF for 3-5 seconds. This output can also be monitored on the scan tool by observing the EVAP Purge Solenoid Command data parameter. |
| Fan High | This function controls the high speed cooling fan relay. When commanded ON, the cooling fan will turn ON at high speed for 5 seconds. |
| Fan Low | This function controls the low speed cooling fan relay. When commanded ON, the cooling fan will turn ON at low speed for 5 seconds. |
| Fuel Pump Relay |
IMPORTANT:
This function is only allowed with the ignition ON, engine OFF. This function controls the fuel pump relay. When commanded ON, the fuel pump relay will cycle ON/OFF for 3-5 seconds. |
| Idle Learn Reset | This function resets the base idle value learned by the engine control module (ECM). |
| ISC Actuator |
IMPORTANT:
This function is only allowed with the ignition ON, engine OFF. This function controls the idle speed control (ISC) actuator. The ECM actuates the ISC actuator for 3-5 seconds when commanded ON. This output can also be monitored on the scan tool by observing the TP Sensor data parameter. |
| Malfunction Indicator Lamp | This function controls the malfunction indicator lamp (MIL). When commanded ON with the engine running, the ECM turns the (MIL) ON/OFF for 3-5 seconds. When commanded OFF with the ignition ON, engine OFF, the ECM turns the MIL ON/OFF for 3-5 seconds. |