Circuit/System Description

The intake air heater (IAH) is located in the air inlet tube and is used to warm the incoming air to aid in starting the engine and for proper cylinder combustion. The glow plug control module (GPCM) will command the IAH ON when the engine coolant temperature is below 40°C (104°F). The IAH is connected to the GPCM by the following circuits:

• The IAH temperature signal circuit
• The IAH command 1 circuit
• The IAH command 2 circuit
• The IAH voltage signal circuit
• The IAH current signal circuit
• The IAH feedback signal circuit

• If there is a fault on any of these circuits, a DTC will set.

Power to the IAH is supplied by the battery positive voltage circuit. An open/high resistance or a short to ground on this circuit will also set DTC P154B.