ecksman

my friends 2001 ws6 automatic cooling fans wont turn on. before i got to it, he went ahead and replaced the ect sensor and cooling fan relays 1 and 2, still fans wont turn on. when i got to it i checked the third relay and its ok. using the wiring schematic on alldata.com i checked the power supply to all the relays and their all good. i checked the wiring from the pcm to the ect sensor and the low and high speed connections to the relays, all ok. i jumped all 3 relays to simulate low and high speed modes, both fans came on as designed. my friends brother has been telling me that the pcm usually fail on these cars and wont turn the fans on. im not too familiar with these cars but im a bmw master tech that knows his way around a wiring schematic and how to use a multimeter. after checking everything on the schematic, all the wiring seems fine. i'd figured i come to ls1 enthusiasts and ask around, maybe theres something i missed or someone could tell me if the pcm are prone to fail. also, does anyone know at what temp the low and high speed fans come on? any help would be apprieciated.