ABS light on and off

Abs sensors on trailer.

 

When you key on, does the light come on for a few seconds, then go out? The first thing to do is wiggle the pigtail and see if you can get the light to flash, it might just be a bad connection. Check for god power at the center pin (Aux). If you have a problem at the center pin, you will get the ABS light coming on every time you step on the brakes, the ABS gets power from the brake lights if there isn't power at the center pin.

Do you know what kind of system it is? Wabco, Bendix, Haldex?

 

What are you trying to check or change? Don't change anything until you diagnose the problem unless you just want to waste money. Identify the system, if you don't know take a picture of it and post it. Follow the service brake hoses from the brake chambers to the relay/abs valve to find it. Once you know what kind of system it is, I can probably help you get the flash codes and get you in the right direction. Anything you do without knowing what fault it has is a guess.

In an extreme case, an intermittent signal or large sensor gap fault could be a loose or bad wheel bearing, so do not let this go too long.

 

Differently check for wire connections and for corrosion at them connections. Including grounding wire problems.

If the wiring code on the truck and trailer match.
Check computer with a code reader and see what comes up.
It may or may not be an ABS problem.
Assuming the dash wiring code is correctly installed from the factory.

 

Wait, differently?

 

HOW TO CHECK THE CENTER POWER?

 

Could you please tell how to test the center pin?