If the Auxiliary Heater is not turning on, please:
In the Service Tool, ensure the 'Heating Option Selector' is set to 'Auxiliary Heater.' This can be found under 'Heating' on the 'System Settings 2' tab.
Testing the auxiliary heater:
In Service Tool, navigate to the 'Climate Info' or 'Real Time Information' tab. Use 'Manual Auxiliary Heater' to turn the heater on/off.
The auxiliary heater will need to prime with fuel before it starts, as the lines will be empty when it's installed.
Check the 20 amp fuse in the auxiliary heater harness, replace if necessary.
Using a multi-meter, check for voltage at the heater connections. Pin 1 should have battery voltage. Pin 7 is the signal wire and should have battery voltage when the heater is requested. Pin 2 is the ground wire.