I'm new to this sight and really like what I've seen so far but wanted to ask. I have 1999 Ford Expedition EB 4x4 and at 176,000 the air ride is finally giving me fits. Last week I purchased a pump and installed it but after doing so haven't been able to get it to run. I know the pump works because I read through the post on here last night on how to bypass the pump and it worked. So was thinking it might be the relay especially after pulling them and seeing some corrosion on the posts.

QUESTION: I noticed there are two relays near the compressor and I believe both of them are the same so can I just "swap" them to test if one is bad? Also, is there anything special I need to do after installing a relay? Called Ford and they are $130 but don't want to buy one just to find out it's not the relay causing the problem. Any other ideas as to what is causing this? I have tested all the fuses as well.