peterbilt 389 wiring help

2020 389, lift axle goes down and up via switch with key off but only goes up with key on. traced all the wires to a relay behind the dash labeled "auto reverser" and by removing the white wire #3600-1 from the relay will allow the lift axle to function normally, hook it back up and it stops working. traced that wire and it ends up going into a split and one end of that goes to the red power box behind the speedo and the other end turns into "wht 3661-0" ive so far traced it out the pass firewall across the front of the firewall and it appears to run into a large harness that goes down towards the tranny? maybe into the chassis node eventually? is anyone able to pull the wiring schematic and tell me where this wire goes, i assume its something to do with the reverse sensor as with that white (ground) wire removed from the relay the lift axle will go up if you set the parking brake but does not go up if you put it in reverse (back up lts and alarm work properly though) vin# 1XPXP4EX6LD716209