Last weekend I had to make an abrupt stop to avoid rear-ending someone in my 1999 Super Duty with 7.3l, 4x4 with rear anti-lock breaks. Afterwards the ABS light was on and will not go off. I've tried the following; Disconnected the batteries and turned on the headlight, checked the fuse (its good), Tried another abrupt stop to the point the rear wheels locked up, replaced the VSS in the rear axel, and used a Autel MaxiCheck Pro OBS2 Scanner ABS Scan Tool. Check for code, there where none, check the ABS, no issue found, used the bleeding function, ABS light still on. When the scanner is hooked up an in service mode the ABS light goes out, but as soon as you exit service, it comes back on. Hope someone has an idea on why the ABS light will not go out.

Malcolm

 

Have you checked that all the calipers are working properly and the pads are in good shape? I've had a caliper actually push itself apart during an emergency stop once in one of my old Toyota pickups. Where's the fluid level in the reservoir?

 

If the ABS light is on, then a code is present.

They go hand in hand... diagnostic trouble codes and dash warning lights.

The logic that turns on the dash warning light is rooted in the presence of a condition that triggers a fault code.

Some aftermarket scan tools, even those that purport to be "ABS" capable... are not able to reliably read proprietary vehicle manufacturer codes that are not mandated to be open source by the EPA.

Try a different scan tool, or a different mechanic who has a different scan tool.

Ford dealership level scan tools, such as the NGS, SBDS, WDS, IDS (all retired) or the scantool that Ford dealers use today (I forgot the acronym for the current system) will all be capable of figuring out what the code is.

I personally use an NGS, as that was the dealership level scantool in use back when these trucks were new. When my ABS light comes on, the NGS can tell me exactly why.

The last time the ABS light came on, it turned out that right front wheel speed senor wasn't reporting a speed in range with the other wheel speed sensors. The scan tool enabled me to monitor the wheel speeds reported by each sensor comparatively, in real time as I was driving.

A proper scan tool will not only be able to report exactly what the Diagnostic Trouble Code was that set the ABS light, it will also be able to monitor relevant PID's to enable the technician to "see" what the on-board computer sees, and thus will see why the computer saw the issue and set the light.

Ford capable bidirectional scan tools can be quite expensive, so a lot of folks have turned to FORScan as an alternative. This might be a direction for you to look into.

 

Brake calipers/pads are in good shape. Reservoir is full. Breaks working fine for stopping, both normal and abrupt. Only thing I can see is the ABS light stays on.

 

I had the same situation, slammed on the brakes, ABS light came on.

used the Edge CTS-3 to look at Codes, and cleared all DTC codes, ABS light went out.