Hi Ben
what a nightmare!
Have you checked the brake master cylinder overun sensors?
These are the big switches that screw into both master cylinder brake diapghrams that tell you if the master cylinders are over stroking.
They can get corroded but are cheap enough to replace or you can sometimes clean them up and get them working again.
and its easy to check their operation ok with a multimeter.
it could be your brake pad wear sensors..A lot of people do away with the brake wear sensor wires now by bridging the plug on each wheel or soldering the wires together.( most truck operators would agree at the end of the day all they do is remind you that a brake pad is coming up for replacement so if your maintenace/inspection schedule are done properly you shouldn't be relying on them anyhow)
again a easy enough to check with a simple multimeter
Also the air presuure guage has a low air warning switch built into it so it could be that
cheers Richard
RICHARDS RESCUE
September 2010
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