Hi everyone, longtime reader (thanks for the suggestion Sous about reading up!), first time posting. I hoped the first post wouldn't be an inquiry for help. I guess I should have posted sooner.

So here it is, I have a 2002 F 250 CCSB, 7.3, 180k, 4R100 Auto (Build date 06/02 so no mechanical diode correct?), 4x4, 4 inch exhaust, Riffraff 6637 Blue filter, with edge evolution (run in STOCK ONLY, just using it for gauges) that has recently thrown the P0781 code, and flashing the OD button. The interesting thing is I haven't noticed any hard shifts from 1-2 or any gear change for that matter. Fluid was changed less than 2k miles ago, was nice and red.
I have read of others having to rev up to 2500 RPM and then let off of the throttle to shift. No such issues here. Drives the same as usual. The only issues I can think of would be a sticky shift solenoid, sticky shift valve, or intermediate one way clutch that can cause this problem, but as it is only a code and blinking OD light and no actual shifting problems I am at a loss? Maybe Mark K could shed some insight into this?
Thank all for the wonderful amount of information contained in this site!

 

Guess there are not any ideas as to what is causing this issue.
Does the blinking OD light lockout the Overdrive in the transmission? Also, is there a way to test the valve body and shift solenoids if I remove them? All gears shift fine with no issues but am getting the P0781 1-2 shift code even after clearing it. It usually comes on again within a few miles.
Its part tow rig/ part family hauler so we depend on this not breaking down in the middle of nowhere.

 

I wouldn't sweat it, MK or Meukster will come along and notice you sooner or later. I'm more lost than you are on AT's than you are so I can't help any.

 

Sometimes I actually have other things to do. FTE is not the first priority in my life.

No, it does not lock out overdrive.

Yes, there is.

Take the valve body apart and look for sticking or damaged valves, or broken springs.

For each of the two shift solenoids put 12 volts across the terminals and see if you hear and feel them react.

Now that you've done all that it is VERY unlikely that it is the valve body or shift solenoids. In fact, it is nearly impossible for shift solenoids to cause the symptoms you're seeing without setting codes for a shift solenoid problem. And you didn't mention those codes.

The mechanical diode was only in the first half of the 2001 model year. No 2002 would have one unless someone replaced the original trans with a 2001 trans.

Very unlikely. If the solenoid was sticky it would set a shift solenoid performance code.
Possible, but they tend to stick every time, not just sometimes.
That's possible. The mechanical diode would cause this. The sprag type one way that is in a 2002 trans isn't known for doing that.

You need to also consider a damaged intermediate clutch. What does the fluid look and smell like? Red? Brown? Black? Does it have a burnt odor?

 

Had a chance to check it out tonight based upon Marks suggestions. I pulled the battery cables off to reset the computer to make sure I was getting accurate codes, drove around for about 20 minutes stop and go, shifts 1-3 mostly. No codes throw, and still no difference in shifting, ie still no hard shifts? The fluid was full, clear red, and did not smell burnt.
Ideally would like to have a BTS or John Woods, but grad school, kids, and a mortgage take first priority.

 

You are welcome for the recommendation.

As Mark said, a lot of these guys just jump in the FTE when they have a moment to get away from their primary roles in life. Although, there are some very, very helpful and experienced people on this forum that range the high level engineer all the way down to the shade tree mechanic working in the dirt.

Keep posting updates and questions and you will get your problem resolved.

Off topic: what part of ID are you in? We have family in Orofino, Challis and Boise. The first two are more my style of living, and the Boise (city) lifestyle we put up with when we have to.

 

Southeast Idaho, out in the dry farms south of Rexburg. Very small except for the University in town. The closest "large city" to us is Idaho Falls pop. 55K. Challis is beautiful, I do a lot of hunting up in the Salmon-Challis National Forest.

 

Like when you have to visit the in-laws?

 

So driving home from work today, finally had the issue where it revs up in first gear and won't shift until you let off he throttle. Threw the same P0781 code with the OD light blinking. Fluid still looks and smells fine. I will try and drop the pan this weekend to see if I can at least rule out sticky valve body or valve accumulator.
Since no mechanical diode to worry about, could it be an issue with the 1-2 accumulator control valve?

 

My sister and BIL lived in Challis for years working for the mine, best fishing I ever had when I would visit.

 

OFF TOPIC: My brother in law is the head Game Warden (DNR officer) for the Challis/Stanley area. When we go out there to visit, he and I hit the good fishing spots as he knows them all.

It is funny we will be out standing in the middle of a river fly fishing with cargo shorts to hold our beer, ball caps and fly rods and that is about it. Then you will get the "walking Orvis catalogs" as we like to call them that are so weighed down by crap they can hardly get to the water.

Sometimes we will take packs and go way up into the mountains for a couple of days with the wives and drink cold beer, eat great food and fish until we cannot stand anymore.

 

So tonight driving it started showing continuous symptoms. It will not shift past first until over 2k RPMs, and then clunks pretty hard into second. All other gears shift like they should. Still just the single code showing.
I will take the valve body apart this weekend, is there a proper procedure to verify that nothing is sticking? I can at least rule that out before yanking the transmission out.

 

What was the problem in the end??

 

@Idaho_F250 what did the issue end up being? @Mark Kovalsky I'm having a similar issue, Same code, plus p0500 for the VSS. I also had P0782 for 2-3 shift and P0733 and P0732 for 3rd and 2nd gear incorrect ratios, which did throw blinking OD lights, but then I replaced the solenoid assembly and trans fluid (which did smell a bit burnt with a good amount of sludge on the magnet, but was otherwise red and clear), and now only P0500 and P0781 are coming back (I did replace the filter with the fluid). Is the VSS somehow confusing the transmission about when to shift? It goes into and holds 3rd pretty solid, and the speedo on the dash works perfectly. Also, the p0781 code took a day to come back after the solenoid swap, so it isn't an "instant" thing. I've been letting off the gas to help it get into 2nd, but the delayed shift isn't always noticeable. Any ideas?

 

What year is your truck, and what engine?

The shifts are scheduled by pedal position vs. vehicle speed. If the VSS isn't working right there will be shift issues. FIx whatever is causing the P0500 code and see if the P08781 comes back.