OK, so got the brake job done...rotors, pads, and new fluid. Drove the truck around for almost 4 days and drives great. Now, today, the ABS light comes on. Not right away but after a couple miles down the road, then comes on steady and stays on steady for the remainder of the drive. Does it every time I get in it too. Any ideas?? Can't imagine what it could be from except for maybe bleeding the fluid, but no air got into the system. Disconnected the battery trick for about 20 minutes too and that still didn't work. It's under warranty but wanted to see if it was something simple before I took it in??

 

Add more brake fluid.

 

On the reservoir, there's an arrow shaped thingie (pointing up) that says max...it's all the way up to just at the bottom of the arrow. Still add more? Just out of curiosity, how could that be it? Did you have that problem?

 

Yeah.. when I did my brakes a couple of weeks ago, I didn't have enough fluid on hand but I thought I could wing it. It was either the ABS light or just a brake light kept coming on. I filled it up and it was a-ok.

Mine was low, though. I'm not sure about yours, just thought that might be an easy fix.

I'd make sure you didn't knock something loose when you were working on your brakes. On the back of the hub, there's a sprocket-looking assembly that feeds back into ABS. Make sure one of the cables didn't come loose or something.

Good luck!

 

Several days ago, I read a post on another forum from a Ford tech that his shop had seen several 04s with an ABS light and a rear diff sensor code that were not due to a faulty sensor. Their finding was a chafed harness near the rail under the driver's door. Repair of the harness fixed the problem.

Personally, I'd inspect that harness and if the problem is found there, take it in for warranty repair. Accumulated failures often lead to TSB (or more) issuance.

Steve

 

Now the brake pedal is starting to pulsate a little bit. It's very random and very light, but it feels like the ABS is making an input to the brake application or something like that. Seems to have no relation to the light either. Pulsates when the ABS light is still off and then the ABS light comes on with no pulsating. Guess it's off to the dealer I go...

 

Found it...a bad left front speed sensor. This had to be one huge coincidence!! There's just no way what we did for a basic brake job messed up that sensor. It's just an electro-magnet anyways. Oh well, covered under warranty and they didn't even say a word about the new brakes or rotors. Got to wait on the part to come in though.

 

Actually it's a Hall Effect sensor, not an electromagnet.

Just mere coincidence.

-Joe

 

What is that??

 

Pretty good animation and simple explanation here:
http://en.wikipedia.org/wiki/Hall_effect_sensor

Same principle as a proximity switch.

-Joe

 

Ahhh yes...proximity switch=electro-magnet.

 

Quick update. This thing just finally got fixed (hopefully for good) last week. Check this out...the ABS problem was due to a warped/bent piece on the inside of the Brembo rotor. The brass colored, notched, tooth thingie on the inside of the rotor that sit's in front of the ABS sensor. Yes, that thing was warped enough for the sensor to loose "contact" with it. By the time we found out what it was, the dealer had already fixed it...and they never so much as questioned the aftermarket rotors/brake job. In fact, the rotor they replaced it with was an exact match to the new Brembo's and looked nothing like the old factory rotors. Yes, they were extremely different. They are also going to extend the warranty on the ABS portion due to the history with the truck. Just thought you guys would like to know.

 

My abs light comes on too. It was after a new master cylinder was installed and some brakes un froze Found out I am getting a bad code reading from rear sensor. I am going to fix it some other time