Theory Of Operation

WARNING: This page is about a different car, the 2019 RAM 3500 HD and 2019 RAM 2500 HD. However, it is still accessible from the selected car via links, so may be relevant.

Heating the inlet air during cold temperatures will increase the fuel efficiency and improves system performance. An Intake Air Heater is used for this purpose. The Intake Air Heater works in two phases, preheat phase (before engine starts) and post heat phase (after engine starts). Preheat phase typically heats the Intake Air Heater coil during the key-on for about 10 seconds to 75 seconds depending on inlet air temperature. The Powertrain Control Module (PCM) controls Intake Air Heater operation with the Intake Air Heater Relay, which is located directly behind the air filter box under the fresh air hose. The Intake Air Heater Relay is not a typical type of relay due to the amount of current passing through it. The Intake Air Heater Relay visually resembles a solenoid in appearance. The Intake Air Heater monitor looks for a change in battery voltage as the heater is turned on and off during preheat, to indicate proper operation.

Note: If the intake grid heater stays on for an extended period of time due to an electrical circuit failure, the intake grid heater element can cause heat damage to the grid heater terminal. This can lead to open circuits or potentially cause engine damage. Engine damage can occur when the bolt and nut from the intake grid heater terminal falls off into the cylinder head intake.