I've been having this strange issue with my braking. I suspected ABS so I have replaced both front sensors and the back sensors to no avail. I removed the ABS fuse and with it out I don't experience the problem. One strange thing though was with the fuse out the speedometer sat at 0 while driving and odometer didn't move. RPM however was working. Is this normal with the fuse out or indicative of another issue? Regarding the ABS I believe the sensors are good ...maybe just something in the wiring or computer? Its getting past my comfort level quickly so I may be heading to Ford to get if looked at. Any suggestions on testing the wiring or further troubleshooting steps?

Thanks,
Joe

 

Vehicle speed is first channeled to the ABS then distributed by the ABS controller to all the other electronics, PCM, dash cluster, overhead display, etc. No ABS power, no calculation.

 

Joe, unless I missed it, you never declared the problem you're experiencing with the ABS. Tough to give an answer without knowing the problem.

 

https://www.ford-trucks.com/forums/1...-question.html

 

The ABS engages often while normal braking. Its been an issue for a while but just recently decided to remove the abs fuse and see if indeed it was the ABS and this has proven it is. Now I either take to ford or try to fix it. I've replaced both front sensors and the rear sensor but this has not helped.

 

Stupid questions. Are the wheels/tires on this truck original, as in the CORRECT tire/wheel size combo? Are they identical on all four, and set to factory spec tire pressure? Have you checked for ABS codes? If the ABS is activating under any unwarranted condition, and there are no trouble codes in the ABS system, then it is likely the ABS "thinks" activation is warranted, as in it "thinks" a wheel(s) is slipping. What is the mileage on this vehicle? Since you mention the rear brakes are applying unwarranted, it may not be a bad idea to pull the rear diff cover to inspect the tone ring, or better yet, remove the rear speed sensor for a look inside while spinning the rear axle one revolution by hand.

 

Good questions:

Not original tires/wheels - 35x12.5 r18 on all 4 (truck has 6" susp lift)

Haven't checked the tire pressure...seems right but would have to verify

ABS activates on unwarranted braking ...just driving and stopping at light

ABS light was on after dealer replaced brake pads then realized they damaged the sensors so they replaced the 2 front sensors and light went off
but still doing the ABS activation in normal driving/stoping.

Haven't looked at tone ring.

 

If those are larger (as in heavier) wheels and tires, you may also want to check on the condition of the front wheel bearings. If there is any excessive play, that can also cause the ABS to activate, since the tone ring is internal and not serviced separately on these trucks. Bigger and heavier wheels and tires put much more strain on the hub and bearing assemblies of these trucks.

 

You need to get a scanner that can read each sensor. If you have a Bluetooth adapter you can use an app on your smart phone such as Forscan.
I wouldn't be surprised if it's a bad front sensor reading. If the abs module sees your front tires are turning slower (front brakes locked up) than the rear then it will activate.
Slightly unrelated but on my Dodge Dakota when I do a rolling burn out the ABS would always activate like you describe.