Hey all,
Vehicle 2000 Ford F250 SD w/7.3 power stroke ,AT, 138,000 miles, No real critical issues in the past. I am very regular with servicing and preventative maintainance.
I last ran the truck this past Saturday with no problems. It sat all day Sunday, not run or moved. This morning I get in and head off to work and the ABS light is lit and won't go out. I get to work and pull it in the shop to check the basics (brake fluid, connectors). All seems normal. I pull the rear axle ABS sensor and replace it. Still same light on. I don't have a code reader.
Could the sensor in the master cylinder give / make this light stay on ? Is there a way I can reset the codes incase the sensor was the problem and the stored codes are createingthe light to stay lit.

Any responses appreciated.

 

Well, first do you have RABS or 4WABS?
'00s and older have RABS w/ 4WABS as an option.
Did you make sure you don't have a blown fuse somewhere?
Unfortunately the ABS/ airbag systems are somewhat complicated. Trying to fix them without knowing the trouble code can be very costly, time consuming, and frustrating.
Also, if you have a hard code, the KAM must be cleared, otherwise you could fix the problem and not know it, because the ABS MIL will stay lit until you clear the KAM. Disconnecting the battery will not clear the KAM either, had that experience before. Some diagnostic codes will clear themselves after a self test, hard codes won't.
I know older trucks had a procedure for disconnecting the diagnostic connector to clear the KAM, as well as getting a code flashout on the ABS MIL by jumpering the connector, but I'm not sure about yours.
I have an ABS/airbag scan tool, which simplifies things greatly, but they are upwards of $850.
Suggest maybe you try a local auto parts store like Autozone to see if they have an ABS scanner and can pull the code for you. Or, try a local shop and kick them down a few $ to pull the code.
Otherwise, trying to fix the system without, is like shooting in the dark, and beyond a few simple checks you are going to need the code.
That's what I know, if I'm wrong or somebody else can suggest an alternative way to effectively troubleshoot the system, I'm all ears.
Not much of a help, but whatever you do, don't start just throwing parts at
it. With the MIL on because of a hard code, you'll never even know if you fixed the problem.

 

Appreciate the response.
The truck has RABS.
All fuses are OK(60 amp under hood and a 5 and 10 amp under dash). I checked them this morning. I borrowed a buddies OBD II scanner early this afternoon and it says there are no codes in the system. Another buddy works for a area Ford dealer, he's gonna bring his ABS specific scanner home and check it. That won't be until Thursday. He says it's very possible that the original rear sensor was bad and that the hard code needs purged out. He didn't say how but said he can do it.

 

Low battery voltage can cause the ABS light to come on. If your batteries are old the cold could be taking its toll.

 

Could be a bunch of things, but if you're getting the codes read with the right reader, that'll tell you all you need to know.

One thing though, check the fluid level in the master cylinder, AND make sure the float switch is working. I think that's the one thing that will light the ABS light and NOT throw a code.

 

Great! So you found access to a scanner after all.
Ya, you need an ABS/ airbag scan tool. A standard OBD/ CAN PCM scan tool will NOT scan for ABS/ airbag codes. Those systems each have their own modules (brains) separate from the PCM.
An ABS scanner will be able to clear the codes. It works the same way as an OBD tool. When you're done with the fix, you tell it to clear the codes. It's that simple.
Very true, low voltage can trigger the MIL. A low fluid level/ sunk float can too, but the brake warning lamp should turn on before, or concurrently with, the ABS MIL, I believe.
The tool will make your life a lot easier tho. Glad you have a buddy with one, saved yourself some $.

 

Well the problem has been solved.
I got in the truck this morning started it and the light was out. Still we put it on a scanner that would check ABS codes. Ran the check and there were no codes in the system. The final diagnoses seems to be that the rear sensor was bad and that after replacing it (and not clearing any codes) and than when the truck was started like 30 times over the next 3 days and no faults were detected the system purged the code on it's own.
Technology, ain't it great. Think I'll start running my F-1 as a daily driver and keep my Super Duty for the weekends.

Thanks to all for your responses.

 

Thanks for the update, glad problem's solved.

 

Sorry for dragging this back up, but I wanted to add to it. My ABS light came on a few weeks ago, and I ignored it, hoping it would go out. It didn't so I climbed under last night, and found a broken wire right by the radius rod going to the drivers front. I spliced it, and after 3 or 4 starts today the light went out. Just a little more info if somebody's searching the forum.

 

Just two more cents to add to the info, my vehicles in cold, snowy, or muddy climates make the sensors dirty and sets off bad codes. Normally I just clean the wheels and the code clears in about a day. Just something to think about before tearing your brakes apart.

 

Thanks for reporting that John!

That's good for a 2WD truck, I think the sensors are exposed on those.

For the 4WD, the sensors are all enclosed - the fronts are inside the wheel bearings, the rear is inside the rear differential. Doesn't mean they don't get caked up with crud though

 

Hi All,
In reference to the abs light on. Here's my little story.
97 f250 7.3 e40d 4x4, bought this thing a month ago and haven't been able to put 50 miles onit yet. I think I have her whipped though. Finally got to the point of hooking up my trailer and decided to check the trailer wiring on the truck, of course the plug was packed with dirt, the terminals were all corroded and had 3 different splices in the wiring. OK, well during the cleanup, i shorted out the brake lights and burned the fuse. Well the computer goes out and checks the brake circuit, if the circuit is dead it activates the abs light "and" prevents you from shifting out of park(not such a good thing when you're parked halfway in the garage, now you can't move, at all.
Plus, thinking that when I set the parking brake for the first time, something happened to bring on the abs light. That prompted me to take a look at the rear brakes, which I found a blown brake cylinder and a weeping wheel seal.
This truck has been cascading snowball of fixes, (tranny, 2 brake cylinders, glowplug relay, transfer case input shaft seal, rearend was full of some kind of goo.) but despite all that I think I'll like it if i get to actually drive it.

This is my 4rth ford truck, 99f350, 94f250, 91f250 and now this one. All 4x4 diesels, so i'm getting pretty sharp at these things. Especailly thanks to forums like this one, they're priceless.

kzdanno