Theory of Operation

WARNING: This page is about a different car, the 2011 RAM Cab & Chassis. 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 30 seconds depending on inlet air temperature. The 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. The Intake Air Heater performance DTC is a two trip fault. The PCM will turn off the MIL lamp when the monitor runs and passes in 4 consecutive drive cycles.