Okay, so I have a PCM/TCM issue where as the PCM/TCM is hot, it loses connectivity with the Trans Temp Sensor (that is all that is obvious, may not be the only thing wrong.) I have verified this is the PCM/TCM by the following:

Replaced the TFT sensor twice.
Replaced the wiring from the PCM/TCM harness to a spot with known good wiring.
Replaced the entire Tansmission wiring harness.

At this point, I am absolutely confident it is either something as simple as a faulty solder joint, or as drastic as a major board issue with the PCM/TCM. It pretty much only happens when the module is hot or has no airflow around it (works fine in the wonderful San Diego mornings/evenings, but immediately has connectivity issues in the afternoon when I go get lunch unless I get on the freeway for a while). I suspect bad joint because pressing on the bottom of the harness improves it, but I haven't been able to reliably do this to a point where I can drive with it for a definitive "this helps".

The questions are:

1) If I swap it, does it have to be with a Second Gen (2005-2007) PCM/TCM, or can any 6.0 PCM/TCM work?

2) If I swap it, does the FICM programming have to be updated?

3) Does anyone have one I can borrow to positively verify my conclusion before spending $1200?

4) Does anyone have drawings I can use to maybe try and dissect/repair this myself? (I have the knowledge, tools, and resources available to do this form a general EE perspective.)

5) Is there any way in the interim that I can send a command through OBD to override the temperature and force a value to stop damaging my transmission?

(e)6) Are there different modules for different localities? (IE, in my sport car - granted it is from 1995 - I know there is an ECU for California Emissions spec vehicles vs Federal Emissions spec.)

Any further input is appreciated. Thanks everyone!

 

Yes it does. There was a change to the CAN in 2005, you can't cross that model year.
I don't.
I never had this when I worked at Ford. I did have the software listing, though. I didn't work on PCM hardware.
I do not believe that is possible. How is this harming your transmission?
There are California and Federal PCMs. The differences are all in the engine calibration. I don't know if changing CA/FED means you need to change the FICM. I do know that the transmission file didn't change between CA/FED.

 

Newbie to forums in general other than searching them and specifically here at FTE, so please correct me if I am not following proper protocol...


Here is my saga...
I bought a used '04 F250 SD Extended cab 6.0 Diesel with about 150k on it about 6 months ago. About a week ago my Tow Light started blinking. Then as I would slow to a stop first it felt like it skipped 2nd gear from 3rd and went to 1st. As I slowed down even more, to less than 5 Mph, it felt like the parking pawl engaged which had the same effect as slamming on the brakes. Then it would not move. I would put it in Neutral then back in Drive and it would work until I slowed down again. This would continue until I turned it off and restarted it. The issue would come and go including the Tow Light coming on. Though I did not feel any flairing I do not think my OD was working while it was acting up.
After researching the forums I came to the conclusion that one solution is to reset the TCM. I have seen several different procedures to accomplish this so I tried 3 different ones. All had the same end result which is where I am stuck now. With some differences, this is how I did: I disconnected the batteries, Connected the cables together, waited 10 minutes, reconnected the batteries, turned on the ignition, waited 10 min, started the engine with all accessories off, waited 5 minutes, turned on AC, waited 5 minutes, then went through the shifting procedure of N-R, wait 5 sec, shift N-D, waited 5 sec, etc. Once that was complete I tried to test drive the truck. It would start to move then it felt like the parking pawl engaged. It only moved about a foot or two. So I tried the reset again but with slight variances that I had found in my research. Like waiting 30 mins with the lights on with batteries disconnected or doing the shift procedure in both normal and tow mode. I still cannot get the truck to drive. Oh yeah, it does move in reverse just fine. So now, if I cannot solve this I have to have it towed to the stealer and have them fix it. I plan to change the fluid/filter, clean the pan out, check the codes (after I buy a code reader), and try to locate the root of problem after I figure out how to get the pawl disengaged. Also fluid color is fine and no burnt smell. I have searched this and other forums but cannot find any threads relating to this exact problem. Any help would be greatly appreciated.

 

Here is the REAL way to reset the computer. Disconnect both battery cables, wait a couple minutes, and connect them again. All of that holding them together, turning things on and off, is just as useful as putting your shoes on the other foot. It does NOTHING useful.

And you're never going to fix this by resetting the computer. That's not the problem. You may have a bad solenoid, or a bad clutch. Getting the code that were stored (they're gone after you disconnect the batteries) would be a HUGE help to determine what's going on. Don't buy a cheap, generic code reader. It will NOT read the codes you need.

Changing the fluid and filter isn't a bad thing, but it won't fix this problem. And when you have it towed somewhere they are going to dump that new fluid you just put in.

When it won't move, turn the engine off leaving the shift handle in drive. Will the truck roll, or is it still being held?

 

See attached. Not sure if that will help any.


TugboatTed, you should create your own thread.

 

Ok, I will start my own thread. I was not sure of the protocol. Is there a way to link or move the rest of the discussion from where I asked my original question so we do not repeat.

Thanks.