Use the Scan Tool Data Display Values and Definitions Information in order to assist in diagnosing control module problems. Compare the vehicles actual scan tool data with the typical data display value table information. Use the data information in order to aid in understanding the nature of the problem when the vehicle does not match with the typical data display values.
The scan tool data values were taken from a known good vehicle under the following conditions:
| • | The ignition switch is in the ON position. |
| • | The engine is running at idle. |
| • | The vehicle is in PARK. |
| • | The doors are closed. |
| • | The windows are closed. |
| • | The A/C is ON, in UPPER mode. |
| • | The ambient air temperatures are at 22-27°C (70-80°F). |
The HVAC Scan Tool Data Definitions contains a brief description of all HVAC related parameters available on the scan tool. 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.
BCM Battery 1: The scan tool displays the level of battery voltage at the body control module (BCM).BCM Switch Inputs A/C Request: The scan tool displays On or Off. The BCM uses the A/C switch input in order to determine if A/C compressor operation is being requested by the HVAC control module.
ECM A/C Disengage: The scan tool displays the None, A/C Pressure, Engine Speed, Batt Voltage, Anti Stall, RPM Unstable, WOT, Launch Perf., Coolant Hot disable of the a/c compressor.
ECM A/C High Side Pressure Sensor: The scan tool displays 0-3570 kPa (0-518 psi). This parameter represents the high side pressure sensor voltage signal converted to pressure.
ECM A/C High Side Pressure Switch: The scan tool displays the High Pressure/Normal status of the high side pressure switch.
ECM A/C Off for WOT: The scan tool displays the high throttle disable of the a/c compressor.
ECM A/C Off Due to Pressure: The scan tool displays the status of the a/c high side pressure sensor. The scan tool displays Active/Inactive.
ECM A/C Auto Recirc: The scan tool displays the status of the recirculation actuator.
ECM A/C Relay Command: The scan tool displays On or Off. On is displayed when the ECM has energized the A/C clutch relay.
ECM A/C Refrigerant Pressure: The scan tool displays 0-4000 kPa (0-580 psi). This parameter represents the A/C refrigerant pressure sensor voltage signal converted to pressure.
ECM A/C Refrigerant Pressure: The scan tool displays 0 to 5 volts. The output of the A/C refrigerant pressure sensor.
ECM A/C Request: The scan tool displays Yes or No. Yes is displayed when the BCM is requesting A/C system operation.
ECM/ECT: The scan tool displays a range of 40-151°C (40-304°F). The ECM applies 5 volts to the ECT sensor circuit. The sensor is a thermistor which changes internal resistance as the engine temperature changes. When the sensor is cold, internal resistance is high, the ECM senses a high signal voltage and interprets the voltage as a cold engine. As the sensor warms, internal resistance decreases, the voltage signal decreases, and the ECM interprets the lower voltage as a warm engine.
ECM Ignition 1 Signal: The scan tool shows available voltage at the ECM.
