Was trying to do a service with 2 sd40's but the mr went lower and lowet till the point the brakes are stuck, nothing seems to trigger the compressor (like described in tutorial) i've decoupled them, both don't fill, tried shutting down engine and restarting cold step by step like in the manual but no results. One of them has 0 psi and PCS open lit, resetting the pcs does nothing.
For some reason the MU-2 valve in trailing SD40-2s is screwed up at the start. All you have to do is toggle it off of "Trail 6 or 26" and back again, and that will fix it. If you don't, the independent brake on the lead unit will fight the independent on the trailing unit(s), and probably the automatic brakes will fight each other as well--both bleeding off air as you described. It's been there since launch, but nothing's been done about it. I guess not enough people have complained.
Thanks! I'll keep that in mind next time, now i got stranded and compressors don't seem to boot up anymore, thanks for the tip, hopefully i won't have this issue in the future anymore
