5.0L, 5.7L & 7.4L "C" & "K" Series Trucks (Escalade, Pickup, TAHOE & YUKON): Description

Auxiliary cooling fan is controlled by VCM based on inputs from the A/C system, engine coolant temperature sensor and vehicle speed sensor. Battery voltage is supplied to the auxiliary cooling fan relay. If ignition voltage is supplied to auxiliary fan relay (coil side). VCM controls cooling fan by relay by providing a ground path.

VCM will turn on auxiliary cooling fan when certain Diagnostic Trouble Codes (DTCs) are present, engine coolant temperature is more than 225°F (107°C) or A/C head pressure is more than 300 psi (21 Kg/cm² ). Auxiliary cooling fan will remain on for at least 30 seconds. VCM will turn auxiliary cooling fan off when engine coolant temperature has dropped 7°F (4°C) or A/C head pressure has dropped to 250 psi (18 Kg/cm² ).

NOTE: Check VCM DTCs that may affect system. If any DTCs are present, perform testing for applicable DTC. Some DTCs may cause auxiliary cooling fan to stay on at all times. Repair all DTCs that are set before proceeding with testing. See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.