To check the ABS sensors, you can also use a digital volt meter on AC volts. Connect the meter to the ABS sensors wires, and spin the wheel. Record the voltage.

Both front wheels should register about the same voltage with the same wheel speed. If one is way low compared to the other, remove it, clean it, and clean the mounting surface. Sometimes rust builds up under the sensor and pulls it away from the tone ring giving a low voltage, which can activate the ABS at low speeds. Chevy actually had a recall on their trucks for this, and it happens to use the same system as the Ford Superduty (Kelsey-Hayes). Of course, the F150 probably uses a different system, but checking the ABS sensor voltages wheel-to-wheel is still a good idea.

 

both front sensors are reading the same. Even though I'm getting a reading from the sensors can they still be defective and causing the abs light to come on ?

 

What's the voltage?

What do you have in the rear for ABS sensors? Check them too.

 

I'll check the voltage coming out of them and see what I get. The rear has the one on the axle top of the pumkin.

 

On the Superduty, the rear VSS (the sensor on the top of the diff) is not only an ABS sensor, but the Vehicle Speed Sensor. I have no idea about the F150.

Does the speedometer ever act up?

Check the fluid in the rear too. Any metal that glues itself to the sensor will cause problems.

 

the speedo doesn't act up. I'll check the voltage, clean the sensor and check the fluid in the diff. I'll post results. Thanks

 

Checked out my repair manual and the F150 has the vss on the tranny and the abs on the diff.

I couldn't get a voltage reading from the sensor as my meter is a cheap one and don't have a low setting on it. I was able to get an ohm reading from it which was 1800 ohm and climbs as I spin the wheel.

I removed the sensor and cleaned it up ( a little grimmy ) and was then able to get a reading of 1900 ohms. I re-installed and low and behold the abs light is off. I love this site. Thanks for all the tips everyone.
The fluid in the diff was grey.....is it suppose to be that colour ?

I know it's not a voltage reading but bot front sensors read the same in ohms 400.

Back to an old issue which led me to this point from a few months ago.
The abs brakes come on at low speed. 20kph to be exact. I can feel it pulsate quit a bit in the peddle then the peddle makes it's way to the floor as if I had no brakes at all... I remember almost hitting a building a few months ago...lol

The abs light does not come on at all when this is happening. Any ideas ?

 

cant help with the ABS, but i had the same grey goo in an Explorer and the light kept coming on. Changed out the lube to new 75 w 140 and that helped the light, and the deposits on the pickup. Pickup did die out 2 years later. Clean lube will help bearing life in addition to the ABS sensor contamination.

 

MICREN...

I am in the same boat as you and looking for an answer.
I had to take the ABS 5amp fuse out. (4th fuse down from the right on panel)
I pull a 28 foot travel trailer and that makes it really hard to stop.
My light stays on with the fuse out and the ABS is de-activated.
I changed the rear diff ABS sensor and still did not fix it.
Very expensive to switch out the front bearings just to test it out. I have NO play or no noise coming from then right now.
$330 each side for bearing hub abs sensor. (Or $230 each side for just the sensors)
If we do not get help here, we may have to do the dreaded call to the dealer service shop for an appointment or just go without the ABS altogether and leave the fuse out.

 

Hey Paul, yeah I hear ya, we're in the same boat. I don't want to have to change the hub/bearing ***. if I don't have to.

There was a link on the first page of this thread to ebay motors where you can get the whole assembly for $80.00

I personally don't think it's the sensors because I'm getting the proper ohms reading off of both front sensors.

But then again, both hubs for $200 isn't bad at all. I will still try and trouble shoot to find the problem. I don't wanna be a "part swapper"

I did the same thing, pulled the fuse. We never had abs in the old days so.........

My question is, say all 3 sensors are good, what else can be the culprit ?

 

One thing that will light the ABS light is the master cylinder fluid being low, or the float switch being bad.

 

Hey Krewat, yes I remember reading that from previous post.

Unfortunatly both mine and Paul's issue does not light up the abs light when the problem accures. Our problem, which mine is that too now since I did resolve the abs light issue is that our abs brakes kick on when going about 20 kph, the light does not come on at this time.

 

What was the voltage coming from the ABS sensors? Anything above .250 volts?

 

Posted that yesterday


I'll bring home a better volt meter home from work today and check....what should the sensors read ?

 

I'm not sure on the F150, but on the Superduty and Chevy with the Kelsey-Hayes unit, it should be at least .350 volts when you spin the wheel at a decent speed (by hand).