Trans won't downshift into 1st or up into O/D

[DvlDogSgt]

My question concerns my 2005 GMC Sierra 4X4 Crew Cab w/4L60 trans.  Problem began intermittently with not downshifting to 1st at full stop, and requiring manual downshift to go into 2nd for take off and then manual shift up into 3rd. Would not shift into O/D, even manually. Problem might last a few miles, or a few days. When shifting properly, trans shifts great with no indication of slipping or any other issues.  I have good mechanical aptitude, but no experience with later model transmissions, just PG, TH350, and TH400's. Any answers or possible solutions will be greatly appreciated.

[tlaw91]

Sounds like a failing 1-2 shift solenoid.


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[DvlDogSgt]

Thanks for the insight.  Is there any way to check this? Check resistance?Continuity? Or is this just a pull and replace part?  Thanks again for the help.

 

[tlaw91]

It being an intermittent issue just pull and replace it’s a $30 part I’d just throw one on there and see what happens


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