Immediately after replacing both front hub/rotors (and front pads and wheel bearings), my ABS light came on and will not go away. I finally ran codes a couple weeks ago while troubleshooting my CPS problem which left me stranded on the interstate while trying to get to the airport for a business trip.

Back in December, all I did was remove, clean, and reinstall the sensors like I always do whenever I have to R&R the rotors. I can't find any damage to the wires or connection points. I have re-removed and reinstalled each sensor again. I have cleared the codes, but once I start pulling out of the driveway, the codes come right back again for both front wheels.

There were absolutely no symptoms prior to the rotor replacement job, and this has been an ongoing and increasingly irritating visual issue ever since I did the brake job back in early December (I can't NOT look at the ABS light every time I start the truck, and I HATE seeing it stay lit)!

What bugs me the most is that I'm getting codes for BOTH sensors after replacing BOTH rotors. I MUST have gotten something wonky, but can't figure out what it was. Now I did replace all the drive line u-joints at the same time, but I never touched anything on the pumpkin or tranny in the process.


So, I have two questions..

1) Possible causes?

2) Possible solutions (I don't want to just start throwing new parts indiscriminately)? From what I've read, Roland posted acceptable ohm values for the front sensors a couple years ago, so I can check that tonight.


Like always, I'm grateful for all your input.

 

I noticed when I greased my Bro in laws front hubs that he had shims on his sensors. Do you have shims? maybe to many? Sensor may be to far from rotor.

 

Good thought, but I have no shims at all. Direct bolt-up.


.... Wait a minute... I guess there might be a chance that I got the bolt's washers under the sensor body instead of under the bolt head (if there are washers... I don't remember at the moment). I'll have to check that.

 

The shims I found were very thin and most were stuck to the sensor. I'm guessing the new rotors had a slightly different diameter trigger wheel thus a different height.

 

The rotors are Napa Ultra P's, and I've used them before without this kind of issue on my Excursion.

 

Do you have a vernier or dial caliper you can measure the reluctor ring with on the old and new rotors to see if they're different sizes?

 

The old rotors have long since been disposed of at this point, so no comparison is possible.

Did not check anything last night. Allergies and sinuses have my head feeling like a lead weight at the end of the day, and tonight is prep work for having my granite counter tops cut in place for a new sink install. That said, it will probably be this weekend before I can dig into this any further right now.

 

I used to have a 2000 X that was 2wd. I once had a wheel bearing go bad when I was about 1500 miles from home and had to use a shop on the side of the interstate to repair it to prevent damage to the spindle.

After closing time and about a mile down the road after paying the bill the ABS light came on.

I also noticed that the truck would wander in the road just a tad.

The mechanic had not tightened the bearing retaining nut enough. An additional 1/2 turn and the ABS light was out but it still wandered. Another 1/2 turn and all was well.

So, you may want to check that as well. I did not have a scan tool back then and it has been so long that I probably would not remember the codes anyway.

 

Interesting thought about tightening the spindle nut, as I can see how it would affect both of my wheels. However, I tend to err on the side of over-tightening those nuts myself, so I know I don;t have much play left on tightening. Also, I don't have any steering wander and I had a complete front end alignment done right after installing the new rotors, bearings, and pads which should have revealed a problem there if it were just the spindle nut. I can still check it, though, just to make sure.

I've also discovered that the used "spare" black CPS I installed almost two weeks ago is acting up, so I'm going to have to swap in my gray one while waiting for the blue IH unit to arrive.

 

Interesting, I'm going to have to do mine soon so report back so we know the fix. Just in case it happens to me.

 

Hey Pete,
I was helping a neighbor diagnose a squeal tonight and it dawned on me(funny what you think of when your working on a truck) you have a 2 wheel drive. I have no idea how a 2 wheel drive is set up. Only thing I've worked on is a 4wd. You did say you replaced bearings and rotors, right. Is yours a bearing unit? Does it come with new ABS sensors? I'm guessing not since you talked about tightening the spindle nut. Wondering if there is a way to check the clearance from the sensor face to the ring?

Edit: http://www.youfixcars.com/ford-abs-light.html

 

Just FWIW, and I'm sure this isn't the case for you, but thought I'd pass it along to anyone else who runs into the same thing...

I just got my truck, and the ABS light was on when I bought it. The previous owner said the ABS light came on shortly after he had the R front hub replaced.

I took off the wheel and rotor to inspect the ABS sensor there, and sure enough, the wire was severed. Whoever re-installed the hub apparently reinstalled the ABS wire in the hold-down wrong and the wire got severed by the corner of the rotor rubbing against it.