Dead thread revival, but since no one answered your question... I am assuming your truck is looking like a lowrider in the back, sitting on its bump stops. The module is located in the front bumper on the passenger side. You need to get under the truck and look upward. You'll recognize it by the heat sink that resides on it. I found lots of info in a ford truck forum. There is also a t-connector for the air lines located in the vicinity of the brake booster that is a known problem. Check to see that it is not broken or disconnected. Also, connected to the rear axle is a limit switch/sensor that could possibly be out. The air compressor could be out (passenger side behind headlight, accessed from under hood. Hope this helps someone.
