I have a 99 F250 7.3L Auto 4X4. Has been running great until three days ago I started it up in the morning. It will not shift to 2nd gear unless i get the RPMs up and let off the gas. At this point, it appears the truck wants to shift all the way to 3rd. It does have a PCM code of P0603, but as I understand that may be nothing as I did try to reset the computer by lifting both battery leads over night. I raplaced them in the morning and still the transmission refuses to give me 2nd gear. I brought it to a small transmission shop and he checked the valves. The diagnosis without talking electrical was that the valves were good (not sticking) and the problem resides inside the transmission. The rig has 200k miles on it but was told there was a recent 3k rebuild (not sure about that). I have heard that it could be as simple as the alternator or battery causing the error, but not sure about the connection to the shifting issue. In any event, does anyone out there have any knowledge on the transmission skipping to third and never even if put there manually going to 2nd?

 

You popped on just at the right time, our trans expert is in the house and he'll get you squared away in a bit.

 

Thanks a bunch. I love the truck and have recently updated the interior to 2005 leather. I had an 06 Harley and loved it. When I lost the tax write off I sold it to my brother. I picked this truck up for cheap but my wife is now stating I spend more time on it than anything else. I will hang in there good or bad. Again thanks for the help and I may be able to sleep tonight.

 

Hey Dallasee

I unfortunately had the exact problem with my truck and it turned out that I needed a rebuild. Mine happened after owning the truck for four days, bummer. The 4R100 seems to be the weak link in these otherwise awesome machines.The only other thing that mine was doing that u didnt mention was that the OD light on the shifter was blinking. My codes were different too P0732,P0733, P0781.The fluid level and smell may be an indicator of internal problems as well. I took mine to the Ford dealership originally and they charged me $100 to tell me I needed a new trans or have it rebuilt to the tune of $2800 with i think 1year 12000 warranty, or a remanfuctured trans for $3500 with a 3 year 100,000 warranty. Most trans shops in the area were in the ballpark of $2500- $3000 with anywhere from 1-2 year warranty 12000-24000 miles and checked my codes for free. If it is the tranny, everone on this site recommended BTS or John Wood. THey are a little pricier in the 4000 range but from what I hear they are bullet proof. I didnt have the money or time so decided to go local and found a reputable performance guy that did custom rebuilds. I wouldn't recommend the Ford rebuild because you're heading down the same road looking to have problems with a stock or close to stock 4R100 which has already failed once. At the very least if you cant afford to go bigtime with the BTS or Woods, find a well recommeded local guy that knows PSD's and discuss the options. A few things everyone told me was to change out the trans cooler minimally (a lot of people say the 6.0 cooler is much better than the 7.3), maybe torque converter and my guy put in additional clutch rings. Hopefully this is way more than you will need but wanted to let you what youd be looking at worst case. I'm pretty new on the site but everyone is great. Good luck

 

P0605 - ROM Error is common for a chipped truck.
P0603 - KAM Error is common for a truck after the battery was disconnected.

In either event, it shouldn't be much to worry about unless the P0603 is persistent. If it doesn't go away by itself after a week or doesn't go away by simply clearing DTCs with a scan-tool, then this could indicate a problem with the ECM where the learned strategies are not being stored during Key-Off.

Best bet, clear the DTCs, turn the key off, turn key on, and then read DTCs again. If P0603 is still present then there is an issue with the ECM or 12v "always hot" lead to the ECM.

If you need any help, feel free to give us a shout and we can walk you through further diagnosis and provide some troubleshooting flowcharts for you as well.

I found the above information in another forum...doesnt look as bad as what I may have led you to believe in my prior post. Hopefully the truck gods can comment on it

 

An over the internet diagnosis is that you have a damaged/failed intermediate one way clutch.

 

I suspect the worst in this case but think the P0603 error code is persistant. I suppose it may have nothing to do with the transmission shifting issue but wanted to check it out. My trans oil is in great shapeand the pan was relatively clean. I know the only way to check the PCM is to verify in and outputs. I tried to pull it out but apparently it is welded in there. Should be some concern right there with the 12 Volt issue but do you think this would cause shifting problems? When the truck is turned off it does not retain memory? I thought it would learn as you drove it longer than X time. I suspect it needs to be thoroughly investigated before I buy a new PCM ($250.00). Is this the right direction?

 

This likely means I have to get the rebuild. It makes me wonder when they say 99 only transmission. I will likely get the "bullet proof" options if there really is sucha thing. So I should brace for the $3-4K. Thanks to all that have been helping me. I do appreciate it and will post the outcome over the next week or so when more information is gathered.

 

i recommend a BTS! Or a John Wood

 

Where did you get the oil check to know that it is in great shape? I can't tell if ATF is in great shape by looking at it, can you?

Welded in? I've never heard of that. I suspect welding on a PCM will kill it, but I don't know anyone that ever tried that.

The only memory in that PCM is to store error codes. It does not learn anything nor store anything other than error codes.

 

Mark,

What I really meant to say is the oil is bright red and not brownish red. The welded in thing was a figure of speach. In reality, I just tried to unplug it with no success. It will not come out. Not sure what to say about the PCM other than I was under the impression it did retain last values from instruments. The PCM will respond to the input with a corresponding output. This is why they say its hard to test and about 50% of the time people replace it in error and does not fix the problem. From what I gather if your going to buy a transmission, get the best. It's a bit discouraging that the prices range from $1700 to $4000. Is there anyone out there who thinks the PCM still may be the problem? Should I still plan to have it checked out electrically?

 

I'm getting emails stating that people are replying to this thread but they do not show up. Not sure what to do? Big Poppa has responded but I do not see it even with the link from the email. I'm logged in.

 

I have a similar problem with my 01 4r100. It only goes into third gear and will drop into second only if I manually shift it. I am told by a transmission friend that it is hydrolically shifting or loading rather than electronically, and probably has an issue with the 12 volt power input to the tranny. Says he sees them quite often with burnt wiring or etc going to the tranny.I have no idea where to start looking to check that. Where do I test the voltage going into the tranny?

Thanks for any help you can give

John

 

There are red wires in the connector on the passenger's side of the trans. When the key is on they must have +12V. Don't push a probe into the female pins or you will create a bad connection where one didn't exist. Probe the back of the connector, not the side where it mates to the other half of the connector.

 

Thanks for answering. I took it down to my friends shop and their computer says my computer is bad. So now I am looking for a computer for it.... doesnt look terribly difficult to get out, just hope i can find one for reasonable...

John