Cold Tranny Won't Upshift Into O/D

[Big G]

Looking for some advise from some smart Ford folks...

Last few days, when my truck is first driven, it is very reluctant to shift up into O/D for the first 3-4 minutes of driving. As my house exits onto a highway, I would normally accelerate to about 60-70km/h right away. I recently replaced a cracked flex plate. I have also checked the fluid level and all seems well. Once the vehicle has made the first shift into O/D (after about a minute or two of driving at 3000 to 4000rpm) it seems to run fine for the rest of the day. Any ideas or suggestions are appreciated.

Thanks,

G

 

[IZwack]

I think that might be normal -- the vehicle tries to stay at lower gears during the first few minutes in order to stay at higher RPMs and therefore reach optimum operating temps faster. However, if it seems to stay at lower gears longer than usual at the temp seems to be lower than usual, then the thermostat might be stuck open.

 

[Willard]

Mine does the same thing....I think it just means you're OD solenoid is getting tired, and doesn't work until warm. Mine is perfect once warm, so I don't even care. Does the OD shift erratically as it warms up right before it works normally?

 

[Big G]

Seems to run fine once it's made the initial shift into O/D.

 

[MrShorty]

3-4 shift (and TCC lockup if you are using OD to refer to that instead) is computer controlled. I don't know the specifics of the algorithms, but I believe that ECT (engine coolant temperature) figures in a little for commanding the shift to 4th gear, and more so for commanding TCC lockup. 1st thing I would do would probably be to inspect the wiring to make sure there are no loose connections. Then hook up a voltmeter across the solenoid and see if the "not wanting to shift" is from the computer not commanding the shift or if the transmission doesn't respond to the command when first given.

 

[BrooklynBay]

The computer sends a ground signal to the solenoid. Both solenoids share a (+) connection, but only turn on when they are grounded.