The HVAC Scan Tool Data Definitions contains a brief description of all HVAC 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.

PCM -- A/C Clutch Feedback Signal: The scan tool displays Relay Off or Relay On. Represents the status of the relay.

PCM -- A/C Compressor Cycling Switch: The scan tool displays Low Pressure or Normal. This parameter displays the state of the A/C compressor cycling switch. The A/C compressor cycling switch is a normally closed switch.

PCM -- A/C High Pressure Recirculation Switch: The scan tool displays High Pressure or Normal. Represents the status of the high pressure recirculation switch.

PCM -- A/C Relay Command: The scan tool displays On or Off. This parameter displays the PCM commanded state of the A/C compressor clutch relay. When the scan tool displays ON, the A/C compressor clutch should be engaged.

PCM -- A/C Request: The scan tool displays Yes or No. The A/C Request displays the state of the A/C request input circuit from the heating, ventilation, and air conditioning (HVAC) controls. The powertrain control module (PCM) uses the A/C request signal in order to determine whether the A/C compressor operation is being requested.

PCM

ECT Sensor: The scan tool displays a range of 39 to +140°C (38 to +284°F). The powertrain control module (PCM) applies 5.0 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 PCM 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 PCM interprets the lower voltage as a warm engine.

ECM

Ignition 1 signal: The scan tool displays Battery Voltage with the ignition On.

Ambient Air Temperature: The scan tool displays -40 to +215°C (-40 to +419°F).

Coolant Temp. Sensor: The scan tool displays C/F. The temperature of the sensor will determine if the sensor is in high power, low power or Off mode.

Over Heat Temperature Sensor: The scan tool displays C/F. The coolant heater will be disabled if the coolant temperature is too high.

Fuel Pump Command: The scan tool displays On/Off. This parameter displays the commanded state of the fuel pump. The fuel pump should be on when the scan tool indicates the Fuel Pump Command is On. The fuel pump should be off when the scan tool indicates the Fuel Pump Command is Off.

Desired Fuel Pump: The scan tool displays ms. When the fuel pump is commanded On the ms signal will be constant and not change.

Glow Plug Command: The scan tool displays On/Off. This parameter displays the commanded state of the glow plug. The glow plug should be On when the scan tool indicates the Glow Plug Command is On. The glow plug should be Off when the scan tool indicates the Glow Plug Command is Off.

Glow Plug: The scan tool displays %. This parameter displays the intensity at witch the glow plug is operating at to create ignition.

Glow Plug Sensor On: The scan tool displays Volts. This parameter displays the amount of voltage being applied to the glow plug.

Glow Plug Off: The scan tool displays Volts. This parameter displays no voltage when the glow plug is Off.

Flame Detected: The scan tool displays Yes/No. If heat is detected in the combustion chamber the scan tool displays Yes.

Flame Temperature Sensor: The scan tool displays Volts. This parameter displays voltage that changes with temperature.

Flame Temperature Sensor: The scan tool displays C/F. This parameter displays C/F that changes with combustion chamber temperatures.

Blower Motor Feedback Circuit: The scan tool displays On/Off. This parameter displays On when the blower motor is operating.

Desired Blower Motor: The scan tool displays volts. This parameter displays battery voltage when the blower motor is commanded.

Blower Motor: The scan tool displays volts. This parameter displays battery voltage when the blower motor is operating.

System Voltage High: The scan tool displays On/Off. This parameter displays On when the system volage is too high.

System Voltage Low: The scan tool displays On/Off. This parameter displays On when the system voltage is too low.

DTC Set This Ignition: The scan tool displays Yes/No. This parameter displays Yes when the system has set a code.