1997 Ford F-350 single cab long bed while driving The truck will shift into what feels like neutral then bangs into what ever gear it wants then starts shifting all over the place .code says speedsonser fault Speesensor replaced with factory pigtail transmission rebuilt 4000 miles ago ABS light is on code was clear but it says fault should not occur so the light blinks once then stays on when ignition is turned on. All of this was happening right when I bought the truck used and I rebuilt the transmission it's still did it but not as much now it's pretty consistent speedometer doesn't bounce at all and when you floor the truck sometimes it just sputters a moment then goes . Pedal assembly replaced didn't work . Possible dash is bad? Battery light keeps coming on charging system is good .

 

You obviously have an electrical problem. Back when I owned a 97, I solved several electrical issues by going around and cleaning all the ground connections on the frame, body, and running 2 new 4 gauge wires from the negative posts on both batteries to the fender and firewall. Is the 3rd brake light working?

 

Is that not a trait of a bad vss?

 

Interior and exterior lights are all working and still working when the problem is occurring Grounds are clean did that already wire wheeled everything and so are the battery posts . Speed sensor is the tranny code that comes up but the problem is that the truck only has this problem when it feels like it . I have a chip on the truck also and I've had thoughts that maybe the ecm is toast

 

Ok, have you removed the chip and driven it and did you change the VSS?

 

Yes still happened but more often . Changed vss with ford one and replaced the pigtail with a factory one

 

I personally would drop the transmission pan and check for debris, however I'm over cautious because of the problems I have had with my transmission.

 

It's something outside of the transmission like sensors etc... Transmission is tight fresh fluid did a full rebuild replaced everything .

 

How long ago? As an engineer I always look back at the most recient work performed.

 

Months ago like 10k miles ago . But this problem happened even before the tranny got worked on but it would go away as easy as turning the key off and turning it back on while driving

 

Id call that frustrating...

 

It's your trans you can do whatever you want but that "neutral" feeling is likely slipping, slipping = heat, heat = fast wearing clutches, debris from clutches = clogged filters or pump preventing ATF from cooling and lubricating parts, no lubrication means replacing forward and reverse drums, front pump, planetary gears, and solenoid pack and having all new clutches inside.

I'm not trying to be an AHole I promise, I'm going through all this same thing right now. My trans was rebuilt when my grandfather owned it, I got the truck with like 60k miles on it, and its having its second rebuild at 65K, part of that issue is the last rebuilder put in aluminum planetary gears in a diesel trans. $1400 in hard parts, $1400 for upgrades (TC, Clutches and band, and valve body) labor at a shop could easily be another 1000-1500 my labor was paid through barter. It sucks I don't have tons of money just sitting around so the $2755 I had to spend hurt, and if I would have just dealt with the issue earlier i wouldn't have had to replace all the hard parts (except the planetary gears).

 

I have a trans temp gauge doesn't get hot fluid is still perfect. It's not a slipping feeling it's literally in neutral won't go no where if you floor high rpm the truck will force it self to shift very hard and o/d light flashing. I guess I just need to bring it to an automotive electrically specialist

 

Replace the MLPS (Manual Lever Position Sensor, sometimes called the TRS or NSS) on the driver's side of the trans.

When it starts to fail it will cause random shifts to neutral. It won't set a code until it totally fails, but it usually causes the trans to fail before it does.

 

I will give it a try