Need help badly guys. I have a moterhome with a V-10 engine. On start-up after sitting the winter in my driveway the speedometer won't work and the ABS lites stay on. The tranny shifts hard when driving harder then I like anyway and sometime shifts back and forth as if seeking. I thought it may be the speed module on the tranny but the only thing I can find on it is a plug on the right side rear over the tranny pan. Am I on the right track? Or just guessing.

 

If you have the same set-up as a pickup ,check the speed sensor on the differential,check the plug connections.It might need to be replaced.I have heard if it is bad it will do exactly what your describing.Keep us informed.

 

I agree. Check the speed sensor on the differential. I had the same problem a couple of weeks ago and that took care of it. Cost $10.60 and took about 20 minutes to replace. (Mine has a sway bar that I had to work around with a box end wrench.) No problem since.

 

Just checked the diff. sure enf there's a pick-up on the top center of diff. Did you replace the pick-up held on with one nut or did you have to replae the plug? Thanks for the fast reply guy's as soon as it stops raining I'll get the job done..........

 

Unplug the sensor and remove the one bolt. Seems that a 3/8 box end wrench worked for me, but I have read that some reported that it is a metric bolt. Once I removed the bolt, I wiggled the sensor and pried it slightly with a flat head screw driver to remove it. I also opend the drain plug on the side of the differential to check the fluid level and rubbed a little of the fluid on the o ring of the new sensor before installing it. There were a few metal filings on the sensor (It's magnetic), but the mechanics here at work said that there wasn't any sign of abnormal wear.

 

Well that did'nt work. I changed out the pick-up just a few minutes ago with no luck.The $10.60 cent item changed to a new model at $17.60 and all made from plastic. seems as if the older model haad a habit of rusting. Anyone have any furtther ideas??? Thanks again.........

 

Never seen the schematics, but seems everybody is on the right track, it is that tone wheel sensor that usually causes your symptoms...

fuse? broke wire? loose connector? recessed pin in connector? Good luck tracking it down... any evidence of squirrles or rats chewing insulation?

 

1st Sgt, Where are the tone sensors? I looked the bottom over seen nothing but does'nt mean I did'nt miss some thing.I had the thing parked for an extended period and there are all sorts of little critters around here.Would it help if I were to put the computer reader on it?.......... I'll try anything right now! N3JIJ retired SMSgt AIR FORCE.

 

Senior Master Sergeant

We keep refering to the tone wheel and confusing you... sorry here is a short lesson:
You wrote:
"speedometer won't work and the ABS lites stay on. The tranny shifts hard when driving harder then I like anyway and sometime shifts back and forth as if seeking".

This typically is an indicator that the computer is NOT receiving the speed pulses from the "tone wheel" located on the rear end RING gear inside the differential.

There is a pickup (that you replaced) that magneticaly creates a electronic pulse every time a raised segment of the tone wheel passes. Faster it turns faster the pulses.

The computer has been programed to use this signal for three basic outputs:

The speedometer is calibrated to compute you tire RPM (revs per mile) and give fairly accurate speedometer needle position.

Part of the speed info is calculated by the ABS computer to activate the Anti Lock feature.

The PCM also uses this signal as part of the "adaptive" (self learning) power and torque computations to control the lock unlock of the TQ and the shift points of the trans.

This may not be all that the pulses are used for, but you can now see why we suspect that you are missing that signal.

Happy trouble shooting

If unable to track yourself consider a goodFord tech reading the codes, I am not sure if some other component of the ABS or Trans Systems may not be the culprit.

PCM is expensive and should be LAST resort.

 

When you removed your old sensor, was it covered with metal filings? Mine had a small amount, but I've read that if the bolts back out of the tone wheel(some call it an exciter ring) that you will hav a lot of metal debris that will likely result in chewed bearings. It is possible to buy a bad sensor, but if you're cofident I would either open up the differential and look for damage or get it to a shop that can trace the electronics. BTW, my sensor was also plastic. I've not heard of a new model sensor. The dealer hear told me that they are common on many Ford vehicles and commonly go bad (although it was the first time I'd ever heard of it). You might want to have your old sensor bench tested to see if it was good or bad. There should be a procedure for that.

 

I have an appointment Wed. to have someone trace out the elec.on the thing. No it did'nt have any medal filingson it. I would have really torn into it if I had seen something like that. I will have someone check out the old sensor though. It just could be possible that the new was bad also. It would not be the first time.Thanks for the input............ Herb

 

Herb,

What did you find out on Wednesday?

 

That fell thru. Guy was to busy working on big rigs to slip me in. I now have am appointment with a Ford dealer on Friday. Talked to a mech. there that really sounded like he knew what he was doing and had worked this sort of problem before. I'll keep you posteed.........................

 

Well I finally took the thing to a Ford dealer. They charged me a wopping $260.00 just to trouble shoot it. Then they wanted me topay them another $1000.00 to replace the ABS Hyd. Control Unit. After I had a third heartattack I walked out of that place with a very bad taste in my mouth. The damn truck only has 21,000 miles on it but as things go the warrenty is run out. I'm trying to get one on the net. Does anyone know if you can jumper the control unit or turn the ABS system off? I got an answer from severl of the parts places but have'nt got down to the price as yet.............

 

I'm definately no mechanic, but that just doesn't sound right. What did they say about your old speed sensor? Was it still good? This one's got me scratching my head too. (and I don't have enough hair left to be doing that) With the tranny and speedo acting up, I was sure it would be a bad speed sensor or something in that line.