1997 Ford F250 LIGHT DUTY ABS/Brake lights on - cannot read fault

Are you following any official service procedures or manuals for diagnosing problems with the ABS? Or are you just assuming OBD II is the way to read codes from it? There is no law requiring non emissions related modules to be accessible on OBD II.

I am going to go check on this in a bit as I should have time today. I am seeing conflicting information here and online that the module may be where you say or up under the dash. My concern is that there is a primary computer module up in the dash and a secondary down on the brake lines which makes sense.

I was driving on some really bumpy roads when this happened and am wondering about a broken wire/bad ground as this wouldn’t be the first time for that on this older used and abused truck.

I finally went out and looked under the hood. There is some type of module with a plug in harness on the lower front of the brake booster with brake lines coming out of it. One goes to the rear and there is no secondary hose or wire going to the front brakes.

I do not know if that module on the brake booster is the main one or something secondary to the one under the dash, if that is where mine is located.

Also, I started the truck and drove a short distance. All the lights were off which makes me think this could be a grounding problem.