my 98 E-350 V-10, after sitting for 5 days popped this little surprise on it's dash yesterday. A week ago I turned the driver's side rotor and replaced the pads. I cleaned off all the gunk from the ABS sensor that reads the toothed wheel thingie. Other than that, nada. It's off til I put it in gear and go over about 5 mph. Should I be worried ? Does it mean the ABS isn't or won't work ? Or what ?

 

Sounds like the vehicle speed sensor. Could be just a coincidence that it happened at the same time you worked on the brakes. It's an 11.00 part and 15 minutes of work. It may be worth a shot.

 

Please elaborate, what, where, how, you know, all that good stuff, and thanks, Ken

 

Mine goes on and off at will. I did nottice that my cab mounted brake light (CHMSL) was burnt so I am going to try and change it to see if that helps.

 

It's on top of your rear differential, held in by one bolt (or nut - can't remember). It's got a wire connector on it, so just follow the wires that go to the diff. Nuthin but gravy.

 

I had the same problem with my F250 and the great folks here on this site led me to the solution to the problem. It started with the ABS light, then the speedo wouldn't work. I was told the next thing to watch for would be poor shifting. I went to my dealer after the advise I got here and told him I needed a vehicle speed sensor. His reply was "Oh yeah, we keep those in stock, common problem". I did take me just a little longer than 15 minutes to work around my sway bar, but it was a pretty simple job, about 25 minutes (including some pondering time).

As jcrice said, it's on top of the rear differential on the left side. Unplug the wires, remove the bolt, gently but firmly pry out the old sensor (it has an O ring), put a little of the differential fluid on the O ring of the new one and slip it in. Bolt it back down and plug it in. Should be good to go.

Hope this takes care of it for you. Let us know.

 

OK so now I'm going to have to break down and swap this thing out. My speedo still works but I now have a check engine light. I'm guessing it's from the speed sensor although it's weird, it almost seems like my truck runs better now. Is that possible or is it just me being psychotic ? I can stop by the local AutoZone and have them run a diagnostic, I have 95K, it may be time for O2 sensors too, but like I said it seems like it's getting better gas mileage and running better. Not that it ever ran bad, it didn't, it's hard to explain. It just seems, I don't know, smoother ?

 

A bad VSS will not make your van run better. In fact, it will probably shift poorly. It usually shows up with the ABS light, not the check engine light. I would guess it is an O2 sensor. A DOFE sensor or AIC will usually make your vehicle run rough. I think your on the right track in checking the codes at Autozone first. Some of the better gearheads here and at flatratetech.com can give you a pretty good idea of what's wrong, based on the codes you'll get and your symptoms.

 

If it's 4 wheel ABS, you may have one of the two speed sensors in the front-end bad. You could have inadvertently damaged the one you removed when you did the pads. They can be quirky. Check it with a VOM. You should have less than 1K ohm resistance. If it's open, it's bad. Just be prepared, the front sensors run nearly $150 a piece compared to the single diff sensor that runs less than $20. Brake Chek or one of those places will give you the ABS codes for free. Good luck.

 

Wow, great info, thanks. I tried to be extra careful with the front sensors when I R&R'd the front pads and turned one rotor. They had alot of metal shavings on the arm that sticks out that I guess reads the toothed ring on the rotors that I cleaned off gently. I had no ABS light til 2 months later maybe. The CEL that came on has now gone off, I still need to get it read, but haven't had a chance yet. I think it only remembers like 6 starts, which I do at least every day. But I appreciate your help, Ken

 

It went into open-loop when the SES light came on. When it's in open-loop (if you don't already know, and I'm not preaching to the choir) it runs at a base-line timing/mix that the engineers put into the computer. Going into closed-loop, it monitors the O2 sensors and adjusts accordingly.

You might be right, it needs O2 sensors, and that's why it runs BETTER in open-loop. Clogged/old O2 sensors generate less voltage over time for the same exhaust O2 content. The computer would see it lean, and over-richen it. That's why you are getting better MPG too.

But I think the SES light may have come on because it's not getting a good reading from the speed sensor. In closed-loop it needs that info and I'm sure it would complain with a faulty reading.

To me, it seems weird that the ABS (and maybe the EEC) would give an error about the speed sensor when the speedo still works, but a lot of people here have said exactly that. The ABS light, then the speedo a little later.

But, it's possible that one of the sensors in the front went. Since you were in there, maybe check the connectors to make sure they are clean and not wet? I know working on my '96/'97 t-bird/Cougar, it's pretty hard to move the caliper without hitting/crushing/mangling the ABS sensor wire

And, on the other hand, if the ABS light was on because of one of the front sensors, the SES wouldn't come on because of it.

Find out what code the computer logged. It'll tell you at least if it's unrelated to the speed sensor,

(was that confusing enough? )

 

Krewat, you're the bestest, thanks for the info. It sure seems to fit exactly, and no, I did not know that about the open loop, I'll let you know what I find out. I could have knocked an abs wire loose or something, I'll check. And I am going to replace the O2 sensors, it's time probably anyway. The CEL came on, the truck seemed to run a little better, it was on for 2 or 3 days, then went off. The ABS light is still on, but the speedo still works, and as far as I can tell, the abs works, although the abs in that van is the weirdest feeling thing I have ever driven. It's almost like the pedal goes dead and the brakes quit working when you stand on the brake pedal, it's a spooky feeling.

 

I don't know if it goes back to closed-loop just because the light goes out. I've cleared codes on my '96 t-bird, and after that, there were diagnostics that were uncompleted, so it had to relearn for a day or two and it certainly wasn't in closed loop until they finished. And that was after the light had gone out after 3 complete-cycle (cold-hot-cold) starts.

As for the ABS, yeah, my truck is scary - darn thing goes limp, none of the other brakes are working at the same level as before the ABS comes on. I have to stand on the brake to get any braking power from it even if only one front wheel went anti-lock.

My '96 tbird/'97 cougar ABS on the other hand (true 4-channel), pumps the brake pedal up hard as heck when the ABS comes on. If you do it on dry pavement without a seat belt and keep your foot firmly on the brake when it comes on, you'll find yourself up over the steering wheel against the windshield unless you strong-arm the steering wheel at the same time as hitting the brakes

 

If your ABS light is still on, there's a good chance your ABS isn't working. I wouldn't count on it anyway until you get the ABS failure code. If the lamp is off when you start the engine, then comes on when you shift into drive or start moving, it's almost surely a sensor failure. The ABS shuts down in that instance.

 

So it's not just me, thanks. The first few times I had to nail the brake pedal I thought I had lost ALL my brake fluid. I had to jam on the brakes once in the rain, one tire was on the center line, but it felt like all 4 tires had just gone into free wheel or something. No pulsing like ABS does, nothing but pure, unadulterated terror that I was going to slam into the car ahead of me, which I promptly did. Fortunately Ford still puts a real metal bumper on it's SD series. And the mini-van I ran into had plastic bumpers so all I did was pop all the plastic rivets out of it. $50 changed hands and we went down the road, not one little tiny mark on he Ford. But I have learned that ABS in a SD means it doesn't lock up because they quit working.