I didnt find anything at all when I searched for "abs" so I am starting a thread. My light turns on, only after moving about 150-300feet after the truck is cranked. If I just sit still and crank it the light stays off. I thought maybe it was the VSS sensors in the front rotors, so I took them out, they had metal shavings on them so I cleaned them well and reinstalled them, no luck. I tried to activate the abs the other day and it will NOT engage, any ideas? Its a 98 2wd 4.6L btw.

 

Mine stays on all the time, I dont get it, reset the computer, had brakes done, nothings wrong light is just on all the time.

 

If the ABS light is on the system has found something it does not like and disables the ABS. It does a self test soon after the trucks rolls and that is way it turns light on at that time. Since you have 4wabs the codes must be pulled by a dealer or at least by a really good scanner. The rear speed sensor is the most common failure but I would pay the $$, have the codes pulled.

 

well if I pull the codes will the abs turn on again? If the code is pulled it would just come back on again later right? IF I could find a dealer than would delete the code for me, any idea how much they would charge? I have a hard time beliving a dealership would erase the code without fixing anything.

 

You cannot just pull and erase ABS codes to reset the ABS lightt. It doesn't work that way. The ABS moulde will reset itself automatically when it finds no fault during selftest.

As always, it must be determined if your truck has rear-only (RABS) or four wheel (4WABS) ABS installed. If you have RABS, you can pull the codes yourself. 4WABS requires a special scan tool to pull the codes.

Once the ABS module has turned the ABS light on due to a self-test failure, the ABS system is disabled leaving your conventional power brakes.

Individual ABS wheel and rear differential sensors can be tested for gross failure with an ohmmeter. A good sensor typically reads about 1000-1500 ohms.

A limited dynamic test can be performed with a multimeter on AC volts. Disconnect the sensor, connect the meter leads, and spin the wheel. A good sensor will generate several volts AC while the wheel is spinning.

Steve

 

Some smaller shops will read the codes for free and clear them(I know autozone does this), but rarely ever do dealers to anything for free.

I've heard Ford cars need a special scan tool that only ford dealers have to get all the codes. Not sure if this is true or not.

Resetting the code will make it go off temporarily, until you re-start the car and it does another self-check, which will re-trigger it.

If you're in a climate(northern states) that calls for ABS protection in winter months, get it checked out. My *** has been saved from a crash more than once by the ABS system, you don't think about it until you jam the brakes and feel the pedal pulse, keeping you out of a spin. Otherwise, it can go until you get tired of looking at the light or have extra cash to get it fixed.

Chances are the sensor is just bad and nothing's really wrong.

 

I think he said he cleaned the sensors on the front wheels so he has 4wabs. I suggest pull the codes and go from there. Like the guy said, ABS is a nice thing and it can save you but, if the fix is reasonable in my humble opinion it is foolish not to fix the system.

 

the most common problem with abs is the rear diff sensor. i would start with that. it's usually only a $60 part and takes all of 15minutes to change depending on your mechanical ability. you could even try a sensor from an auto wrecker if it's cheap enough.

if that doesn't work then go and spend some money on diagnostics.

 

this is all really great info, thanks a lot guys. I'm gonna test the rear sensors and replace whatever is bad.

 

The rear diff sensor cost me less than 20 bucks but did not fix my light. I know it is the culprit for most people however. I need to ohm out my front sensors one of these days but the light has not bothered me that much. You cannot pull codes on some of the ABS systems. You have to short some pins and count flashes etc. Depends on year and model of your truck. My system has no codes on the OBD port but my light is on.

 

where is the rear "diff" sensor located? Is there one on each drum or actually on the differential itself

 

Top of differential itself, towards drive shaft. One 10mm bolt.

 

1st - it is probably the sensor on the rear differential. 1 - 10mm bolt holds it in. $20 at the dealer, a little less elsewhere.

2nd - When you search, you have to put a * at the end of any string that isn't 4 characters or more. In other words, to search for ABS, you would search for ABS*. Also, do your search in the Brakes forum.

3rd - You should post Brake-related questions in the Brake forum.

4th - You probably won't be able to retrieve the ABS code with a typical code scanner - the ABS system has it's own computer. Same goes for the airbag system in the truck as well.

No slam or flame intended, by the way...

 

ok I replaced the rear diff sensor, and its a no go. Guess i will have to test the front sensors with a meter again. BTW does anyone know where the abs relays and fuses are? I dont have a manuel so I have no idea what fuse is what, anyone know where i could get that info without buying an owners manuel? Thanks

 

Adobe .pdf copies of owner's manuals back through 96 or so are available for download from www.fleet.ford.com under the Maintenance heading.

Steve