3500 4x2 Pickup L6-359 5.9L DSL Turbo (1994)
Air Intake Heater Relay: Description and Operation
Intake Manifold Air Heater Relays
LOCATION
The Intake Manifold Air Heater Relays are located in the engine compartment below the left battery.
OPERATION
The Powertrain Control Module (PCM) operates the intake manifold air heater through the intake manifold air heater relays. The relays may be
energized before and after cranking, depending upon intake manifold air temperature. The PCM monitors intake manifold air temperature through
the intake manifold air temperature sensor.
The relays are not energized during engine cranking. When they are energized they make a clicking noise.
CAUTION: When testing, do not energize the air heater relays more than once per 15 minutes without running and operating the engine. Due to
the high amperage needed to operate the heater, the batteries may not have enough time to recharge. Wait 15 minutes before turning the key back
to the ON position.
