We have a 2009 (build date 2007) Thomas C2. It is equipped with an air operated Transpec stop arm, original to the bus. Recently the stop arm will not deploy nor do the lights light. The amber/red warning lights on the bus operate as normal, just not the stop arm. Wondering if anyone else has had this issue and what you found was causing the problem. Thanks.
Iíve seen this many times on my earlier C2 models, most of mine are non- air but the wiring for the sign is the same for both. I usually start out by checking to see if there is anything else on the bus thatís not working. I had a few with heated cross view mirrors that would short out and blow a 30amp CHM fuse under the hood that would also take out the backup beeper and stop sign but not blow the 10 amp stop sign fuse in the side panel. Some have had spread pins in the stop sign harness in the side wall causing bad contact. Iíve also seen a few where the wiring that runs above the windows has chafed against the back side of the radio speakers causing a broken wire or blown fuse.
Iíd check every fuse in the bus, then Iíd pull down the first few curtain rail panels behind the driver and locate the splice saver(think cable signal splitter) and test from there and then move onto the plug inside the wall behind the stop sign. The power, ground and trigger wires for the stop sign run up the side pillar to the splice saver and from there run back down to the front of the bus or to the rear of the bus if you had a rear stop arm. You should have 12 volts constant on wires numbered 490 and 12 volts on wires numbered 489(trigger wire) when the sign is activated. Wire 489 is used to activate the air solenoid and the internal flasher in the blade and is controlled by the chassis hub module. It sounds to me like you might have an issue with the trigger wire, but on a C2 stranger things have happened. Sorry for the long read.