Auto transmission Lock - Up

[Bob Ellithorpe]

Just trying to understand my automatic transmission !!



If I use the OD button to lock it out. the transmission will shift three times. Then if I push the button (light goes out), the transmission will shift two more times.

Correct me if I'm wrong but, I'm assuming the first shift after releasing the button is the TC locking up and the second shift after releasing the button is the OD locking up.

Just drove truck today and turned (should say tried to turn on the radio) and nothing happens. Checked fuse (OK) and have power to fuse - any hints or suggestions??

 

[Joe G.]

Bob,



When you push the button the TCC is already locked up in 3rd. It drops that lock, shifts to OD, and locks the TCC back up again. The stock trans will not shift with the TCC locked up so it drops the lock for the shift to OD. If you watch your tach when you do that you will see a quick increase in RPM just before the shift.

 

[Jim Fulmer]

Joe G. is correct about he shifting unless you mod it with the mystery switch... ... I don't know about yours but if I'm in OD and put it on the wood it won't down shift or unlock it just pulls the truck along but I like that, I was talking to greg at TST the other day and he seemed puzzeled that mine worked that way normally, are others different?



Jim

 

[Dieselnerd]

Jim, mine has worked like that from day one. When locked up in OD it doesn't downshift unless you push the OD button no matter how hard it's pulling. If it's locked in 3rd with OD turned off, stepping on it unlocks the TC but it never does this in OD. I mentioned this when I had my transmission upgraded and was told that many were like mine. Like you, I don't want to change it either.