Not always. If the wave form is still there to the ABS it's still working so no ABS light. But with the signal varying at low speed it thinks the tire is slipping.

 

Great, thank you. Ill report back later with the readings. For the squealing... i think it is coming from the rotors because when i spin the tire, i hear a squeal only at one part where it contacts. wonder if it is warped

 

Warped is highly overused. The Ford rotors don't really move around.

You may have an issue with the splash shield which does bend easily and can be contacting the rotor. I'd check that first.

 

i kept hearing about warped rotors but then about how hard it is to get them to warp, so i wasnt really sure. ill have to check that out too

 

Thirty years of vehicle testing says ................ no.

Now if the truck had composite rotors like the older ZJ Jeeps or Taurus then we are talking a very different story.

 

[quote=acf6;11883126]Ok, i need to get this figured out before i just bring it to the dealer (which i might do anyways)

On the truck in my sig, i am having a weird brake problem that feels like ABS coming on. The only time it happens is when i am just about at a complete stop, maybe going 3 mph at this point, and the brake pedal pulses and drops, truck shakes and the wheel jerks hard to the right. If i keep pushing the pedal it will go away and stop fine, or if i let off and then brake again it will stop fine. It feels exactly like ABS coming on, but only for a split second and it keeps doing it on dry pavement. Happens maybe 2 out of 5 stops. Already checked my brake fluid, just replaced the slide pins (didnt fix anything)

Also have a very loud squeal that seems to pulse on and off (and faster with more speed) only on right turns. fairly positive that is in the brakes, but not sure if it is related??

if it only squeals when turning dont overlook a bad hub assembly. The wheel speed sensor is in the hub assembly and could definately casue abs issue because the hub assembly has play in it and can not read the tone ring as well because it is moving around. Jack it up and grab the tire at the top and bottom and check for movement. If there is movement have someone help you determint where it is moving(hub assembly, ball joints ect)

 

i just jacked up each front side and disconnected the abs wire from behind the splash shields. i had my multimeter set on the AC auto metering function, and the right side was reading around .160 volts (voltage went up with faster tire spin) and the left side was barely hitting .014 volts (and not climbing with more wheel speed)

 

alright. i dont know if i said it before but im not that great with the front end of these trucks yet. by hub assembly do you mean just the thing on the outside that you switch 4x4 on/off with? or is it the whole thing the wheel bolts onto?

 

It looks like you found the problem. Evidently, the ABS module thinks that LF wheel is locked up and is activating to release it and let it spin. As I said before---load the sensor up with penetrating oil, and hopefully it will come out with no problem.


RON

 

^^^^^ do this part. the low voltage reading could be caused by bad wheel bearings that are allowing the hub (tone ring) to move away from the sensor, which could be good.

usually they will give you a resistance spec for the sensor, which is more accurate of a test for the sensor.

hall effect sensors voltage will drop with more air gap between the tone ring and the sensor, so the sensor is probably good and reading speed above 10mph, but the excessive gap will cause it to drop to 0mph when the vehicle slows below 10, while the other properly gapped sensors will read road speed as lows as 3mph. the module see the one wheel drop to 0mph and tries to free that wheel from a skid.

also leading me to believe its a wheel bearing (in your case...unitized hub) problem is that it is squealing when you turn, which is often caused by the loose hub "floating" and allowing the lateral g-forces to push the rotor against the caliper. when one pad is applied to a rotor (instead of both, like normal brake function) it WILL squeal.

we are in LI for a while so i cant physically help you at the shop unfortunately.

 

What do you think I should do for now? Will we be able to replace the hub?

 

And so what side do you think it is? Still the left?

 

jack up the front end, and pry up and down on the front tires. see which one (or both) is loose.

WE wont be able to change it, because the drilling mafia is out of state for the next several jobs. you could probably find a how to on here or youtube, its an easy job if everything comes apart, or its a horrible job if things are siezed. also, you will need all your vac seals on the front end or your 4x4 wont work.

 

this is a little extreme but a good example:
Bad Wheel Bearing - YouTube

 

Thanks Aaron. How long are you guys gone for? I'm sure I could manage it with a write up but if something goes wrong I might have a problem. How much money do you think those things go for?