Radiator Cooling Fan Control Module: Description and Operation

GENERAL
The fans may be activated by either air conditioning pressure, engine coolant temperature or transmission fluid temperature. Refer to Radiator and Transmission Cooling fan Operation Chart in the illustration. The Powertrain Control Module (PCM) turns on the fans through fan relays. The transmission fan is wired in parallel with the radiator cooling fan. Therefore, both fans will operate when one of the three activation conditions are met.

PCM CONTROL
The PCM provides fan control for the following conditions:
^ The fans will not run during cranking until the engine starts no matter what the coolant temperature, A/C pressure, and or transmission fluid temperature is.
^ Fans will run when the air conditioning clutch is engaged, low pressure cutout switch is closed and once set compressor head pressure is reached. See chart.
^ Fans will run if transmission's on-board diagnostics records a malfunction (Limp-in mode). Refer to appropriate Powertrain Diagnostic Procedure manual for diagnostics provided.