I have a 2002 F250 4wd, while driving the abs light flashes on, and the speedo drops 30 mph, then returns and the light goes out. it does not flash out any codes at strart up. the front wheel bearings are new, and the vss on the rear diff is new. it also intermittently feels like it has a misfire, and loss of power, but does not set the check engine light or any codes. any thoughts.

 

Normally I would suspect the speed sensor on the diff, but you said that was new. Did you check the oil to see if there was excess debris inside the diff. Sometimes that will confuse the sensor.

I don't know your model year, but other times when I had similar problems, it was a loose vacuum hose, usually going to the Airconditioning controls near the fire wall on the passenger side on my 94. Not quite sure why it would set an abs code, but it has on mine a couple times.

SOmetimes with loose vacuum I would get ABS errors, odd speed readings and sometimes a check engine light. The hoses come off quite easily if you are working on that side of the engine.

Hope this helps,

Jim Henderson

 

I will check all the vacuum hoses and connections when we get back on sunday. I will also check the grounds, connetions to the abs computer, and the coils and plugs. I have heard some other strange tales about weird things setting off the light and drivability concerns. I will report back If I find anything. and open to any other suggestions. thanks

 

cat2000zrt - have you made any progress on your abs/misfire issue? I have the identical symptoms that you have described on my 2002 F250 V10 with ~90K miles. Any insight would be greatly appreciated.

 

My 2003 F-250 4x4 (4 wheel abs) abs light is coming on and off at about1100rpm's with the truck in N and my foot off the brake peddle. If the truck is moving the light comes on at about 25mph which again is about 1000rpm and the speed-O well drop-off to 0mph. The truck has a small miss at ideal any thoughts. (no engine codes- no abs codes- all wheel speed /tranny sensors ohm out good and are clean).
Thanks
Steve






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Any word on the fix?

 

My girlfriend's F-250 has been having issues with the ABS light coming on and the speedo acting up at the same time. I replaced the oil in the diff(with the limited slip additive) as well as the VSS on the differential. She gets the ABS light sometimes when going up hills or when she hits a bump. I'm starting to suspect a wire grounding somewhere. I ordered a new ABS sensor for the front passenger side since the ABS light went off when she was turning left the other morning. Not sure if it was on this forum, but someone said the sensor cables are made such that they are put under a lot of stress when turning the wheels. This causes the wiring to pull free of the sensor and that can cause issues. I'll let you guys know what I find out.

BTW, I had an issue with a standard VSS from AutoZone not working worth a crap so I ended up replacing it with an actual Motorcraft part. It improved dramatically since then. I guess I'll take it out, check it, then check for the wiring. The teeth that the VSS monitors for wheel slippage all seemed fine when I had the differential cover off, so I don't think that's the problem.

 

Thanks for the tip I'll try changing the oil this weekend.

 

O.K
After pouring over elect. diagrams I found one common tie between the abs and the ignition system so I brought the trk. to a friend who has all the fancy stuff and asked what he thought about the engine miss causing the abs light to come on.He L.O.L at me and told me to put the tail pipe down, so we put it on his Dyno. and a few minutes later he had counted 250 miss-fires and every time it miss fired the abs light came on, He told me that fords software for the engine it not any where as touchy as the abs so that is why there was no check engine lite, but the abs would pick it up.He told me it was a bad coil but couldn't say which one.So all I could do was buy a new coil an start at the #1 coil replace it with the new one if that fixed it great if not take the one I had just removed an place it on a the next one in line until I find the bad one. (GOOD TIME TO CHANGE YOU PLUGS AND BOOTS)
Six tries later it was the #10 coil ,miss went away and so did the abs lite.Don't no for sure if it was back feeding up the power wire thought the ignition or was plain old R.F at work. Let's hope not that would be scary. Hope this helps and may the force be with you. GOOD LUCK!!!!!!!!

 

HOLY SH@T ***** BATMAN !!!! what are all you guys sneaking over at night driving my truck ? lol i just went through all this crap .
1) vss changed on pumpkin . found some small metal chips . that took care of the abs lite . told mech that it felt like something was holding it back or a skipped tooth feeling . never thought of a misfire . mech said maybe something with the brakes making it feel like holding back .
2 ) slide on 2 calipers stuck.1 front ,1 back . replaced brakes and rotors .
changed fluid in rear . while underneath they noticed the center bracket for the driveshaft was shot . changed that .
life was grand for a couple of days , now its doing the "misfire " again wich all makes sense now . any idea of how much it cost to do the coil ( s ) ? i just went through $900.00 for all the other stuff

 

$45 each at rockauto.com for motorcraft. So $450 for 10

 

is it better to do 1 coil at a time or just go ahead and change all . also if i change plugs and wires im looking at some serious ching .do i have to change the plugs at the same time or would coils be considered part of a tune up thanks

 

I bought only one new coil because I knew at lease one was going south on me. As far as the boots and plugs change them only if you want I only suggest this because you well be up their and may be moving a few of the coils around searching for the bad one.Please also keep in mind that ford had trouble with spark plugs striping out in the hole's on the V-10 so take it slowly and when going back together do the next guy who has to do the plug's(which will probilably be you)a favor and use some good quality anti-seize. I got all my parts from the local auto parts house (O'Reilly's) I think the coil was $40- boots $6-8ea and just went with the auto-lite plugs.Basicaly after-market stuff.

Good Luck
Steve