Engine Control Module Scan Tool Information. Chevrolet Joy 2008

For 1990-2009 cars

Table 1: | Engine Control Module Scan Tool Data
Table 2: | Engine Control Module (ECM) Scan Tool Output Controls

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.

Note: 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
A/C Evap. Temperature Sensor (If Equipped) | -- | -40° to +130°C (-40° to +266°F) | This parameter displays the temperature of the A/C evaporator core based on the input to the control module from the A/C evaporator temperature sensor signal circuit.
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.
A/C Request Signal | A/C ON | Yes | This parameter displays the state of the A/C request input to the control module from the heating, ventilation, and air conditioning (HVAC) controls.
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 IAC Position | -- | Counts | This parameter displays the desired idle air control (IAC) position as commanded by the control module.
Desired Idle Speed | -- | 800 RPM | This parameter displays the desired engine idle speed 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 | -- | 88 to 105°C (190 to 221°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 | Engine Idling | 0.6-0.75 Volts | This parameter displays the actual EGR pintle position in volts.
EGR Solenoid Command | Engine Idling | 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 Run Time (If Equipped) | Engine Operating | 0:00:00 Increments when the engine is operating | This parameter displays the time elapsed since the engine was started.
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
EVAP Purge Solenoid Command (If Equipped) | -- | 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.
Fan High | -- | ON/OFF | This parameter displays the control module commanded state of the fan relay control circuit.
Fan Low | -- | ON/OFF | This parameter displays the control module commanded state of the fan relay control circuit.
FC Relay 1 Command | Engine coolant less than 108°C (226°F) A/C Off | Off | This parameter displays the control module commanded state of the fan relay control circuit.
Engine coolant greater than 108°C (226°F) A/C On | On
FC Relay 2 and 3 Command | Engine coolant less than 108°C (226°F) A/C OFF | Off | This parameter displays the control module commanded state of the fan relay control circuit.
Engine coolant greater than 108°C (226°F) A/C ON | On
Fuel Level | -- | 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
HO2S 1 and 2 | -- | 0-100% | This parameter displays the voltage output from the HO2S 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.
IAC Position (If Equipped) | Engine Idling | 15-40 Counts | This parameter displays the engine control module (ECM) command for the IAC pintle position in counts. The higher the number of counts, the greater the commanded idle speed reads. The IAC responds to changes in the engine load in order to maintain the desired idle speed.
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.
Idle Switch (If Equipped) | Engine Idling | ON | This parameter displays if the engine is at idle. The parameter will change from ON to OFF when the engine is not at an idle.
Ignition 1 Signal | -- | B+ | This parameter displays B+ when the control module detects a voltage at the ignition 1 input terminal.
Injector PWM | Engine Idling | 0-9 ms | This parameter displays the average pulse width of the fuel injectors as determined by the control module.
ISC Command (If Equipped) | -- | 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.
ISC Motor Position Sensor (If Equipped) | -- | 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.
ISC Motor Position Sensor (If Equipped) | -- | 0-5 Volts | This parameter displays the actual position for the ISC motor position in voltage.
Knock Sensor | -- | 0-5 Volts | This parameters displays the voltage input to the control module from the knock sensor (KS).
Long Term FT | Engine Idling | 0% | This parameter displays the commanded Long Term Fuel Trim correction by the control module.
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.
LT FT Cruise/Accel. | Engine Idling | 0% | This parameter displays the commanded Long Term Fuel Trim correction by the control module for cruise and acceleration conditions.
LT FT Idle/Decel. | -- | 0% | This parameter displays the commanded Long Term Fuel Trim correction by the control module for idle and deceleration conditions.
MAP Sensor | Engine Idling | 32-40 kPa | This parameter displays the pressure from the MAP sensor to the control module.
MAP Sensor | Engine Idling | 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.
O2S/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.
Octane Level | -- | Counts | This parameter displays counts.
Short Term FT Avg. | -- | -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.
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 | -- | 2-10 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.
SVS Lamp Command (If Equipped) | -- | OFF | This parameter displays the control modules commanded state of the service vehicle soon lamp.
TP Sensor | Engine Idling | 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 Position 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 Security Status | -- | Disabled | This parameter displays the status of the vehicle theft deterrent system. The normal parameter display for the theft deterrent system is Disabled. If a condition exists with the theft deterrent system the parameter will display Enabled and the vehicle will not start.
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 | Note: This function is only allowed with the ignition ON, engine OFF. This function controls the A/C compressor relay. When commanded ON, the A/C compressor will cycle ON/OFF for 3-5 seconds.
CO Adjust (leaded fuel only) | Note: This function is only allowed with the ignition ON, engine OFF. This function resets the learned values for the idle speed CO Trim value in the ECM.
CO Adjust Value (If Equipped) | Note: This function is only allowed with the engine idling. This function allows you to adjust the short term CO Trim value and programs the final adjust for the long term value.
Crankshaft Pos. Variation Learn | This function enables the engine control module (ECM) to learn the variations in the crankshaft position (CKP) system.
EGR Solenoid | Note: 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 | Note: 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 | Note: This function is only allowed with the ignition ON, engine OFF. 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 | Note: This function is only allowed with the ignition ON, engine OFF. 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 | Note: This function is only allowed with the ignition ON, engine OFF. 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 Injector Test 1-4 | This function cycles the selected fuel injector ON/OFF 8 times.
Fuel Pump Relay | Note: 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 | Note: 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.
ISC System | This function resets the learned values for the idle speed control (ISC) system in the ECM.
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.
Reset ECM | This function resets all the values learned by the ECM.