Lost overdrive after restoring to factory programming

[Southerntester]

I have a 2007 GMC Sierra and am using a Diablo Intune I-1000. Bought the Diablo years ago to turn off AFM and it worked great. Haven't touched the programmer for 10 years.

Recently noticed some hard shifts from 1-2 and while trying to eliminate any possible issues I restored the factory programming / setttings using the Diablo programmer. Had no issues, no warnings and everything seemed to work as expected as far as the programming process.

Went for a test drive and now overdrive is gone. Tried one of the custom tunes just to write something in hopes it would fix this issue but no luck. Restored the original once more, the write went fine but still no overdrive.

Any suggestions?

FYI - trans is shifting is much smoother now thanks to an aftermarket 1-2 accumulator upgrade.

[mikel]

Cant say this is something we've ever seen or heard of happening.

Let it read a backup and post that here so we can take a look.

[Southerntester]

IF (big IF) I did this correctly these should be the backups.

Hopefully it's something easy that I've missed.

Thanks

[mikel]

There's nothing here that doesn't belong.
try a battery disconnect

[Southerntester]

We appreciate you taking a look. Last night we tried the gas pedal key reset procedure and unhooking the battery terminals for about an hour, neither helped.

Hooked up our Xtool scanner and the computer is calling for the transmission to shift to 4th, it just doesn't happen.

If the Diablo Intune had turned off OD for some unknown reason would the computer still show a command to 4th gear?

Grasping at straws here... never had an issue with our trans and really struggling to believe OD just happened to stop working when we made these changes.

Thank you

[mikel]

have you tried messing with the tow/haul button, since that disables OD?

[Southerntester]

The button appears to work as it should, like comes on when the button is pushed and goes off when it's pushed again.

Transmission doesn't shift into OD either way.

Thanks

[mikel]

I am at a loss here. I can only tell you we've literally tuned 10s of thousands of these trucks over the past 20 years, and I have never heard of this happening. I cant in any way correlate it to anything the tune could have done.

[Southerntester]

Wanted to follow up and say thanks for the help.

The issue didn't end up being programming, just seemed that way with the timing of events.

The servo vent hole was blocked, keeping it from shifting into OD.

Cleared the blockage and it shifts like a dream.

FYI... never use RTV to seal transmission pans.

[mikel]

glad you got it sorted out!