the ABS dash light on my 03 F150 is staying on. anyone know what is going on?

probley a weel speed sensor.

When the ABS light is on that means that the antilock control is disabled the brakes still work just like normal. Couple things to check first is the fuse for the abs control second most common cause mentioned before is the speed sensor. You can take it somewhere and have the code read as long as the fuse is good then that might point you in the right direction. I'm not sure what the resistance value of the speed sensor is spec'ed at but if you read 0 or a short or open then that's a definate sign it's bad. Here is a link that might help.

http://www.ohmcheck.com/abssensor.htm

Found what I was looking for see if this helps

http://www.f150online.com/forums/2449609-post9.html

Just replace the rear speed sensor. Its mounted on the top of the rear differential- they're about $19.00 from the ford house. Its about a cheap a guess as you'll get.

well its not the wheel speed sensor. i wasn't getting any reading on my voltage meter when i put the leads in the plug at the end of the wires leading to the sensor. i guess its a bad wire somewhere? what do you guys think???

i dont think you will get a reading, the sensor is like a pulse generator, as weel in the diff or where ever its located passes over the magnet in the sensor it makes a pulse and sends it back to the abs module, take it to auto zone and see if they can read the abs codes, that will tell you whats wrong. now you can take the sensor out and see it its cracked if it is that very well maybe it.

its the sensor id bet mine did the same thing its a 25.00 part, a lot less than a diagnosis charge, buffaloman is right on the money

you can also buy a version of all data diy. it offers alot of infornation on repair. i use it on my gmc and my ford truck.

www.alldatadiy.com

I had to read this a couple of times but now have some questions. With the plug separated the leads going to the sensor is what you were reading with your volt meter, were you trying to read volts or resistance? You should have been trying to read resistance and if so and you didn't read anything then verify your leads to the meter by shorting them together and if they are good then since you didn't read at least 1200 ohms then the sensor is bad. On the other hand if you were reading the leads coming from the computer harness going to the sensor unless you had the ignition on and engine running then if you were trying to read voltage it would be minimal like possibley less that 5vdc. Sorry I'm just confused as to what and which direction your trying to read with the meter. But then again I usually am that way normally.

no the sensor is good, i was measuring resistance, plus i put a new one in just to make sure. i also checked the plug coming off the wires with the engine running, and got nothing.

check all fuses, maybe one is blown, if not it maybe the module is bad.

It just dawned on me that you prolly got the 4 wheel anti-lock (told ya I was slow) there are 2 more sensors to check one on each front rotor. As suggested check the fuse for the abs controller. It's hard to say not knowing what the problem is without knowing the codes. I've heard cases of problems with the pump not working and the culprit being a wire between the controller and the pump. First check the fuse and front sensors with the ohm meter. If that's not it then get the codes read. Let us know what you find.

here is something else. it may not apply to yours but worth a look. i had a ford escape in the shop a couple of times, the owner took it to the car wash and washed the engine, well water seeped into the plug with the red and black wires. it melted the bronze tab in the module, at first i didnt see what was wrong but
after a closer look i saw that the water corroded the tab away. take a look at the wire connectors for moisture and corrosion. just a thought

Yep, Water is the biggest enemy of electrical components. Now a days these modern vehicles with all of the electronic components they don't recomend power washing the engine bay area. And more so I have made it a practice any time I disconnect any plugs or harnesses a dab of dielectric grease goes on just to prevent moisture from getting in the connectors.

where are the sensors on the front rotors? i've never noticed them when i change my brake pads.

behind the front rotors. you may have to take them off to replace them.

thanks, i'll check them out when i get home in 2 weeks.

Hi,

I am having the same problem. My truck is an F150 heritage. When you say "the plug with the red and black wires" which plug exactly do you mean?

Also, where exactly is this located? I ask because this problem began for me after a week of very, very rainy weather and I was doing some work on the truck with the hood open during some of the drizzle..

locate the abs module it will be a box with a motor on it with brake lines running into it, there should be a plug with wires, take it off and check for water damage

Ended up being the front left sensor.

Glad you found it.

awesome. glad we all could have helped

i had it coded, they wanted over 200 bucks to change it out. i'm going to do it myself. can i change it from the backside, or does the rotor need to come off?

disconect the battery first, you may need to i dont remember.