I have a 1999 Ford F350 7.3 4x4 with an ATS 4R100 auto trans that has about 35,000 miles on it. I was having some problems with my trans fluid heating up and at one point while towing my fifth wheel it overheated in the red. Once I made it home I flushed all the trans fluid and installed a new filter and fluid.

On my next trip out without towing the fifth wheel I noticed that it would not shift into 4th gear. I cannot say for certain if it wasn't shifting into 4th before the above problem or not though, but I thought it important to mention the trans fluid overheating in case that caused some other underlying issue.

Anyways, the details of the issue are I can get it into 4th gear if I toggle overdrive off and then back on but only when around 65 MPH or so. It will then shift into 4th gear smoothly. This has been working fine up until this week where now I cannot get it into 4th at all. I can toggle overdrive off and then back on and it will shift momentarily into 4th and then drop back into 3rd.

Shifting is smooth through all gears and even into 4th, the split second it actually is there. I inspected the overdrive wires in the steering column at the recommendation of someone here on another thread and they are fine. I have no CEL's and I took the truck to a friend of a friends shop to use their reader and I have no trans codes along with no overdrive light flashing.

I know very little about transmissions and am at a lost. I have read somethings about some sensors that I believe are the TSS and OSS and they can be dirty or bad. I also know there is the solenoid pack that is fairly easy to swap out. I don't want to through a bunch at money at parts and am seeking the vast knowledge on this site for help.

I don't believe it's mechanical with the trans as it feels and appears to shift normally. I thank you all in advance for your help.

 

You'll need a high end scan tool that can look at live data. Is the computer commanding the shift but it isn't happening? Or is the computer not commanding the 3-4 shift at all? Is the problem really the torque converter isn't locking? These questions can be answered with data. I don't know how to diagnose this without data.

 

I agree with Mark. Data is needed. I don't think there is an issue with the Solenoid Pack, unless you are experiencing TC lock issues. The combinations of "on-off" for the SSA and SSB solenoids seem to be working, as your 2 & 3 shifts are normal. In OD, both solenoids are "off". If there were a bad shift solenoid, one of the others shifts would be affected. The TSS and OSS are used to determine the range/gear that the trans is operating in. Usually the rear (OSS) sensor is the one that can be dirty. It "might" be possible to have a defect, but I would think you would experience some weird things with your other shifts if that were the case. A lot of metal on the OSS can indicate the possibility of something internal failing. Most codes set due to electrical problems, or feedback from the sensors, that indicate "conditions out of spec". This is why data/codes are important in diagnosis. Throwing parts at something is not the answer.

 

Did you ever figure out the problem this is the problem with my truck

 

I had to finally take it to a transmission shop and ended up being a loose bolt somewhere on the valve body that would not let fluid flow properly to get it to shift to 4th. I'm not a trans guy so I can't explain much more then that to help you. Maybe someone on this forum can steer you in the right direction and what bolt effects 4th so you can check it.

 

Feedbolt!

Mark above posted sometime ago that they do have to be checked for torque when you have the pan down and filter R@R;d.

He's saved countless members many dollars with his advice.

Denny

 

Truck wont shift into overdrive and shifter light not blinking anymore so I can't pull codes from it but I did pull one yesterday that was p0781

 

Why can't you pull codes? Once a code is stored in memory it stays there for about a month after the last time the light flashed.

P0781 is the code for a 1-2 shift error. This says that there is something wrong with the 1-2 shift. It doesn't say anything about not shifting to fourth gear.

 

well that is wat pulling up on scanner and tried to pull codes earlier today and nothing come up wen Im drivin truck it wont shift into overdrive unless I shut off the truck while running down the road and fire it back up then only will it shift

 

Maybe you need a better scanner.

 

where is this "feedbolt" and what is the torque value for it?? sounds like something to check when you drop the pan it appears. I was going to be doing a pan drop and fluid change out here in the next couple months. might be a good time to take care of that as well..

 

The three feedbolts are located between the case and the valve body. Once the pan is off you remove the valve body and the feedbolts will be visible.

 

so I guess my next question is how difficult is this to do on the ground with trans basically upside down.. I make the mistake when replacing the valve body and removed another valve part and just about lost a couple of the rubber *****.. (thanks to mueckster aka Roland for photo diagram where the ***** go ) guess you need to be real careful when taking it down plus the truck has been sitting for the past month without running so most of the dripping will have stopped.. I might open drain plug and let it sit for a week as well to get all the loose fluid out.. (I put a note on steering wheel to remind me. )

EDIT: in reading some other threads it seem this issue is sorta diagnosed by the trans slipping in and out of gear when just cruising.. in a post U9000 stated.. "Mine seemed to be losing pressure, as in slipping out of gear while normally traveling (not doing anything stupid-just cruising)." When he did a removal of valve body did find the three feed bolts "1/2 turn from full torque" .

SO wondering if I do not have these issues, shift smooth with a JB valve body, when cruising in gear no issues both bobtail and pulling 30 ft airstream so might be better to "let sleeping dog lie.."" or not to worry for now?? all I was wanting to do was fluid change any ways.

 

If you have experience removing the valve body you already know how to do this. The only other part is using a torque wrench to check the feed bolts. Once the valve body is off the feedbolts are out in the open.

 

@carl2591 there is information on this procedure in the 7.3L PSD Tech Folder