ABS Broke!?!?

Abs is hard to mess up. It's just a sensor up against a ring. Probably got mud on the ring. If you're lazy just buy 10 cans of brake cleaner and keep spraying it until it's clean

 

Mud and dirt in the drum

 

If the ABS light is on its likely from moisture on the contacts.
You'll find that it happens A LOT in rainy and/or snowy weather.
Grit and grime find their way into those contacts and wreak havoc.

You can spray the brake cleaner, or WD40 onto the connectors and it may help, or wait until conditions dry and they'll probably go away themself.

You may have to turn the truck off and reset the System, then move the truck a bit to get the light off, but it normally fixes itself.

Until its really a problem. Then you need to fix it. When it's not fixing itself in dry conditions and application of water dispersment... it's time.

That yellow light is a big bright GET ME signal.

 

@oldioldi
One thing to check if your LIGHT is on.
Turn the ignition OFF and stand at your step.
Turn the key to the ON position , but don't crank the engine... just to the ON POSITION .

Listen to see if the system cycles.
It's usually a 4 click timer.
You'll hear one under the tractor and one under the trailer tandems.

If you need to, you can just hear the tractor, then with the key still ON, unplug the pigtail and plug it back in so the two cycle clicks don't drown each other out.

If they CLICK.. the system is very likely in working condition and you just have a corroded sensor.

It may dry, or you may need to unplug it and brush the green off of it.

You'll get this.

 

If your trailer abs light stays on continuous from key on, check your sensor ends in the hub.
Could be the mud pushed the sensor a way from the tone ring where it is mounted.

You can push on the back of sensor towards the hub to reduce the gap.

Wabco: Easy Stop Trailer ABS Manual - West Coast Enterprises
PDFWest Coast Enterprises › OpManualsPDFs

This link might help understand.
Good luck