HELP!! Air pressure gauge issues

Hello, new to posting. I've ran out of options and am completely stumped. I have a 2006.5 W900 (it has the new style gauges) My primary, secondary, and brake application gauges are all messed up. Long story short I was driving down the highway when all of a sudden both air gauges dropped to 50 pounds the dinger and the lights on both gauges came on. There was really nowhere to pull over so I down shifted to raise rpms and I soon heard the air dryer blow off. So I breathed a sigh of relief and kept driving. Got back to the shop and I've been trying to figure out what the problem is. I cleaned all the battery terminals both ground and positive, cleaned the ground on starter, motor, and firewall bypassed each gauge in the wiring sequence tried switching all the pressure sensors around and still nothing. The brake application gauge is at about 30 and both primary and secondary gauges are just above the red. sometimes when driving the light comes on and the dinger goes off and sometimes its just above the red. If I take the brake application wire out of its sensor and put it to the primary or secondary air pressure sensor it still reads 30psi. If I take the primary or secondary air gauge wire and put it to the brake application sensor it still reads the same. Even if its completely out of air it will always be at 50 psi. The only time they will go to zero is when you turn the key off. The cruise control doesnt work because the brake application gauge is at 30. If you unplug the sensor at the fire wall the cruise works. I've tried everything I can think of. My last resort is to buy a icu but i am hoping someone has some input before i drop 2k on a new one. Any ideas?!?! Thank you very much in advance!!

 

Correct. Builds air like it should blows off like should.

 

Its definitely a gauge issue . If you pull out the sensor both primary and secondary the air comes out like crazy. If you pull out the brake application sensor and apply the trolley valve air comes out.

 

Yes

 

The ECM or the ICU?