2001 7.3l Auto O/D light blinking

[Hatrick]

Hello Gal's/Guy's, I have been a happy owner of a 2001 Ford F-350 Lariat SuperDuty 7.3l Automatic 3 spd O/D crewcab.
I have owned this truck since 2005, this issue arouse in the spring of 2009. This issue happened when not under any stress, 4 passengers, no payload, not towing. I was on a 80 mile trip west of home. One mile from my exit the O/D light started blinking and I lost O/D (4th). No problems with 1st,2nd, or 3rd. I came home and let it cool down over night. I started it and drove down the road, O/D was working and every thing great for the first 5 min. Just after the trans gets up to temp, Again the O/D light, and I loose O/D function. I must park truck and turn it off, restart it and disable the O/D, and it performs without issue. I’ve been driving the truck with this issue going on 4 years. I have a OBDII code reader. When the O/D light comes on have attempted to get OBD codes. There are never any. No check engine light just O/D light on shifter knob flashes, till I pull over and turn the motor off. I disable O/D while in park and it works fine with out O/D. I fix all my vehicle issues, and never take them to the shop.
I’ve read a lot of forum posting’s only a few described this issue, I have seen no fixes as of yet. I’m going to step up my trouble shooting to you now, mabe one of you help me pin point a fix. I don’t think it is a rebuild issue. Because it only effects O/D. There has never been anything bad found at the bottom of the pan. The tranny fluid was stressed/aged but not burnt, it has been changed since the problem first happened. I’m leaning toward a weak Solenoid shifting pak and or weak or sticking valve, this is where it gets me. Why would O/D work while it is cool and then fail 5 min into warmup? Heat/resistance building up in the solenoid pak, causing the O/D solenoid to fail??? In the Solenoid pak?
I'm hoping your sugestions will help me get my mind arround this problem, your suggestions are welcome.

Thanks
Dave In Albuquerque with out O/D

[NoRalPh]

Here's how it works, the Flashing OD light is essentially the SES light for the Transmission. Your OBD-II scanner is pretty much useless for this (if it's one of those Generic readers, it's pretty much useless for the truck in general which are Not, specifically, OBD-II).

There ARE codes related to the transmission that will direct you to what's wrong. You need to get it on the right equipment to retrieve them. Most professional scanners (Ford, Snap-On, etc.) will do it. Most recommended for end-users here is the AutoEnginuity (@350) for the long term care of your truck if you're a DIYer

[Hatrick]

Originally Posted by NoRalPh

Here's how it works, the Flashing OD light is essentially the SES light for the Transmission. Your OBD-II scanner is pretty much useless for this (if it's one of those Generic readers, it's pretty much useless for the truck in general which are Not, specifically, OBD-II).

There ARE codes related to the transmission that will direct you to what's wrong. You need to get it on the right equipment to retrieve them. Most professional scanners (Ford, Snap-On, etc.) will do it. Most recommended for end-users here is the AutoEnginuity (@350) for the long term care of your truck if you're a DIYer

NoRalPH,

Thats the kind of information I was looking for! Thank You!