How’s it going fellas. I’ve pretty much done all I’ve can and used the tm. I replaced the pressure censor replaced batteries checked continuity on wires and the rear air brake gauge keeps dropping out of no where and back up. I’m suspecting there’s a bad ground but can’t seem to figure out where. If you guys have any info or have ran across this issue I would appreciate it.
.
Sure seems to me like you might have a grounding problem.
If the air pressure really went down to zero,
you would slide to a stop when the spring brakes applied (automatically). That is what those extra chambers are made for on the rear axles.
On these trucks, the drivers may or may not roll up the windows when they park the truck. It might rain and unlike their personal vehicles - I don't see them running out to roll up the glass... On the passenger side of the truck where the co-driver sits, there is the electrical panel (fuses and circuit breakers). On the drivers side all the dash wiring. Disconnecting the batteries and cleaning every electrical contact in sight would most likely help you with this problem and a lot of others too. Electrical Contact cleaner and Anti-Ox paste and about two solid days cleaning is what needs to be done...
.
