I have a 2007 SEL and it has had this problem for the last few months. The PCM power relay ticks after you turn the key off. The TPS also ticks in time with the relay. Unplug the relay and plug it back in and it stops. I've researched this problem and have heard causes were anything from a weak ground to the high pressure switch on the A/C compressor to a bad PCM. I just replaced the PCM and had it reflashed by the Dealer and this problem continues. I've even ran a separate 4 gauge ground from the battery to the PCM grounding lug. The only codes it has ever thrown are P0442 or P0444. I had a shop in Dallas diagnose it yesterday, and they had no idea what the problem could be. Has anyone other than me had this problem? If so, how did you fix it? My wife loves the truck, but I'm getting tired of throwing money at it.