EFE Heater

AIV Solenoid
Energized at all engine temperatures [1]
Energized engine temperature between 15° C (59° F) & 60° C (140° F)
Energized engine temperature over 70° C (158° F)

EGR Solenoid
Energized engine temperature below 60° C (140° F)
Energized engine rpm less than 800
Energized engine rpm more than 5200
Energized vehicle speed below 11 mph (18 km/h)

Fuel Pump Relay
Energized whenever key is on [2]

Mixture Heater And Relay
Engine running
Energized engine temperature below 50° C (122° F)
De-energized after engine temperature exceeds 50° C (122° F) [3]


[1] During deceleration only.
[2] Only for 5 seconds if engine is not started.
[3] Turns off after several minutes.