The transmission in my 99 F350 7.3 just quit on me (sort of). With the gear selector in Drive the transmission acts as if it's in neutral. If the OD is turned off it shifts normally. Park, Reverse, Neutral, 2 and 1 all operate as they should. No codes so far.

Update 1: Fluid is full and clean
Checked range selector inputs, all seem normal: Park-14, Reverse-12, Neutral-10, Drive-8, Drive (OD off)-6, 2-4, 1-2
Gear commanded by PCM is 2 in all ranges except 4 when range is in 2.

Update 2: Coast clutch solenoid is being told to engage only when range selector is in 1, 2, or Drive with OD off. As soon as OD is enabled the PCM is commanding the transmission to coast. Is that how it's supposed to work?

I noticed the same coast clutch solenoid state in Reverse, but the truck moves. Guess I need to read the service manual some more to figure out how it works.

Also, transmission has PTO (not used) and was remanufactured by Ford, unknown date.

 

I've had that happen to one of my 4R100s.

Yes it is.

Your problem is a failed overdrive one way clutch. When the coast clutch is engaged it takes over the job of holding from the one way clutch. The trans has to come out to fix this.

 

Thanks for the fast reply (and accurate as always). I was hoping it was something in the electrical control system that I might have had a shot at fixing myself. Oh well, I've had the transmission out before to replace the flex plate and torque converter. Looks like I get to do it again.

Do failed overdrive one way clutches typically self-destruct and do more damage or can I drive it OD off for a few days?

 

No, they usually don't. The one I had ran about six months like that. It was actually a company truck that we didn't have time to fix. So we just drove it the way it was until there was a slow time.

 

Best news I've heard all day, gives me a little breathing room.

Thanks again Mark.

 

Just out of curiousity, is this one of the potential symptoms of a failed o/d snap ring?

 

No, it is not.

 

My truck is also having a similar problem where it won't move if the OD is on. 1,2 and reverse are all working with OD on but Drive is not. When I turn the OD off it will drive like normal. When I get up to speed let's say at about 50 mph and turn the OD back on the truck will continue to drive like normal but once it slows down to about 40mph and downshifts it will not drive anymore and will act like it's in neutral until I turn the OD back off again. Is this problem the same thing as the one way clutch for overdrive?

 

Yes, it is.

 

Same issue here boys, if some one can help me out. Just rebuilt my 4R100, the clutches were smoothed out in the middle. Was coming off an exit, went to yield, hit the gas nothing. Anyway, got it all rebuilt, not going into overdrive. It would work at first with OD on, took it out to double check everything, put her back in, and now still not working, however, this time when I shift into drive, nothing. Does like above says, acts like its in neutral, I hit OD off on shifter, it engages and goes, however it wont go into OD while driving, cant get above 40 MPH. I have put new Shift solenoid and both speed sensors, same issue. any help would be amazing! going on 4 weeks now, looking into MLPS if that's the problem, not sure where else to look.

 

Look inside the overdrive clutch. I suspect it may have come apart.

 

Ok cool, that's what I suspected, everyone told me it has to be electrical, so the overdrive clutch will cause it to not pull, then when the button is turned off it will pull, im dreading pulling this out a 3rd time lol

 

Oops sorry it posted 2 times and I couldn't delete

 

Originally Posted by zignorsj
My truck is also having a similar problem where it won't move if the OD is on. 1,2 and reverse are all working with OD on but Drive is not. When I turn the OD off it will drive like normal. When I get up to speed let's say at about 50 mph and turn the OD back on the truck will continue to drive like normal but once it slows down to about 40mph and downshifts it will not drive anymore and will act like it's in neutral until I turn the OD back off again. Is this problem the same thing as the one way clutch for overdrive?
Mine just started doing this except it takes a while to shift 1 to 2 but after I get up to 50 i can turn od on and it will shift into od and it's fine until I come to a stop then I i have to either drop it into first or turn od off.
My fault codes are p0733 p0732 p0603 and p0731 I think or it's 734 I don't remember the last one but the diag says shift solenoid 1 electrical fault/ yes error and shift solenoid 2 electrical fault /yes error
when in first gear shift range 1 and 2 are open when in second 1 and 4 open when in drive 1 2 3 and 4 are open. Speedometer is working correctly and no other issues with truck.

 

So it won't move with OD on and in drive? If that is true, the overdrive one way clutch has failed. You also have electrical problems, but that isn't the cause of no movement in first gear. That's a mechanical fault.