I pulled the headlight and can easily find the compressor. There is a module mounted on top of the compressor that has the air intake line mounted to it. I'm not sure if this is the relay you mentioned. The four prong wiring connection on the compressor was clean. I took out the compressor to see if I was missing something mounted underneath but there is nothing else mounted in this area of the truck. The four prong plug looks to have power(blue/red) and ground (black/white) but I can't find out where the two smaller wires (black/white & brown) are coming from that lead to the module mounted on the compressor. I'm assuming a module of some sort controlls the air in and out of the bags. I could not find anything in the engine bay that looks to be linked to the compressor to tell it to come on or off. I had shut off the air suspension via the computer/dash board thinking it would stay at the same height. When I drove the truck this morning, the rear end eventually dropped so I turned the system back on. The pump started right away but the back end did not raise immediately. It eventually raised back to normal and stayed there for theXXXXXhome. I live in Minnesota and we have had plenty of snow and salt on the roads so it does point towards electrical but I don't know where to look next. Thanks again. Chad
The part you are looking for is on the passenger side . it is normally accessed from underneath the bumper ( pass side ) I can't find a diagram for your truck . And the indication is , that the relay for the compressor on your model is in the under hood relay center . I am in Canada and our Vehicles and some of our service info differs from U.S. models . Here is a diagram ( not very good ) showing the location of the " Solid State " relay for the Suspension compressor . I am sorry but I can't tell you for certain that this will be exactly the same as yours .