BTW, diagnosing a leaking AMU is easy. For finding any air leaks, I use a 3 ft section of 1/2" OSD or smaller plastic hose. Place one end near your ear (not in your ear, haha) and slide the other end in the slot behind the back side of the AMU's. The sound of the air leak will be magnified, By measuring how far back you slide the hose, you can determine which AMU is leaking.
The brake lite switch AMU was found after talking to a FL dealer who asked if the brake lites worked intermittently, which they did, and told me it was probably the AMU. With a test lite and wifey on the brake pedal, determined he was right. Dealer could not get to me till the next day so I went to the parts department, printed me out a schematic of AMU blocks on my truck, bought the AMU and installed it in their service parking lot in about 20 minutes, and retained the nice OH to Laredo run. They sent a scout out to replace a mirror on a truck next to me to covertly check on what I was doing. Heck, all they had to do was ask the parts department, LOL.
Further ideas to eliminate the air pump from cycling so much (and maybe pick up a tenth or two in MPG), other then your basic air line repairs and replacing the cheap FL plastic air line connectors and elbows with brass, is to install a manual air pressure switch and gauge for the sleeper air springs. I got the idea from my Donvel front air springs which come with such a switch and gauge. I tried this after linking the fact that my air pump used to cycle more (every 10 to 15 minutes) on the roughest roads compared to smooth (every 20 to 25 minutes). The air spring equalizer valves, sleeper and rear air suspension, where constantly adding and releasing air, more so on the rough roads, although the rr suspension valve not as much and left it in tact. After running the manual switch for the sleeper air springs and bypassing the equalizer, it now will go 1 and 1/2 to 2 hours between cycling. Note the sleeper air spring equalizer was not leaking, just doing it's job, albeit overworked by my better halve's load of household etc. items in here LOL. She once loaded a Minibago motor home with so many rocks and junk in the back, I could literally pull the front wheels off the ground with a little coaxing on the 7.4 liter gas pedal. I got some funny looks when I pulled in front of the St Louise arch popping wheeleys.
Oh, and lastly, a little "Slime" registered tradename, squirted in an air spring and rolled around a bit will repair any small holes. Going on a little over a year since doing this on a sleeper air spring and still leak proof. I run about 95 PSI in them at all times.
Again, just on man's shade tree ideas that work for me. Your results may vary, should you attempt the same.
