2003 ram diesel auto trans in limp mode, cant find problem

hi

im at my wits end here

all was ok,
i went on an hour trip all was fine,
left to head home and

-Starts off in 2nd or 3rd,
You can manually shift into first
-doesn’t go into OD or lockup
-OD light won’t come on or off
-no cruise control
-gear indicator only lights when in neutral or park, unless key is in accessory position then all light

Replaced:
Pr lockup solenoids “solenoid pack” 52118500AB
-governor solenoid 4617210
-prindle/neutral safety switch 56045489AC
-transducer solenoid 56028196AD

-adjusted shift cable
-adjusted safety switch
-checked and cleaned all grounds and grounded PCM
-left both batteries disconnected overnight to clear codes

-removed fuse block under hood and cleaned all connections,

-replaced the TCM , it was flashed to the vehicle

its not throwing any codes

any new ideas?

Heard of similar things happening to guys with a tuner or other aftermarket stuff. I wouldn't rule out the main computer if yours is still stock. If you have a tuner try resetting everything back to factory and see if there are any changes.

'03? Truck is getting old. There's probably a chafed wire somewhere. Limp mode 'protects' the trans from further damage when it sees something WAY out of whack.

Quick story - about 10 years ago my '01 Cherokee would go into limp mode because a connector in the charging system harness was being pulled apart just enough to make everything go blank for a second. The TCM would lose all voltage signals and shut down. No codes. This was happening because someone (not me) had wrapped the harness around the trans dipstick tube and every time the motor would torque over, it would pull the connector apart. I replaced all sorts of stuff too with the same result. Once I saw the harness, I lifted it up and let it hang loose and it never happened again. Nothing to do with the trans at all.

That's the type of stuff that can cause the truck to go into limp mode. Go back and check all your connections, make sure nothing was moved where it didn't belong, etc.

Ultimately, you probably need to find someone with a DRB scanner to take it for a ride. You need to try and reproduce the symptoms of when it happens and monitor some things on the scanner while driving to pinpoint the issue. Might not get it on the first try. Most likely be looking for a wacky voltage reading or something to drop out for a second.

pretty much that....^^^

find it hard to believe someone ponied up to replace an ECM over a trans limp in issue. They certainly don't give those away.

sure it's stock??