EFE Relay

Air Regulator
Energized when key is on [3]

AIV Solenoid
Energized engine temperature below 70° C (158° F) [1]

EGR Solenoid
Energized engine temperature below 65° C (149° F)
Energized engine temperature above 105° C (221° F)

Fuel Pump Relay
Energized when key is on [2]

Power Valve Control Solenoid
Energized when engine rpm is over 4000

[1] During idle or deceleration only.
[2] Only for 5 seconds if engine is not started.