05 Yukon/New guy

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Skipper50

TYF Newbie
Joined
Apr 16, 2016
Posts
7
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8
Location
Galveston county, Texas
SE Texas, '05 Yukon XLT 1500
Replaced rear seal and oil pan to stop leakage. Tranny was dropped for this.
Following reassembly the transmission will not shift.
Found and replaced failed brakelight switch.
Still not shift.
Fluid levels are good.
Can't find anything impeding shifting.
I'm thinking the TCM lost it's mind.
Suggestions?
 

swathdiver

Full Access Member
Joined
May 18, 2017
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26,633
Location
Treasure Coast, Florida
Replaced rear seal and oil pan to stop leakage. Tranny was dropped for this.
Following reassembly the transmission will not shift.
Found and replaced failed brakelight switch.
Still not shift.
Fluid levels are good.
Can't find anything impeding shifting.
I'm thinking the TCM lost it's mind.
Suggestions?
If the torque converter moved and is not clicked in all the way then it has to come out. Let's ask Nick: @NickTransmissions
 

NickTransmissions

Sin City
Supporting Member
Joined
Mar 9, 2023
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1,116
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2,709
Location
The transmission bench
Replaced rear seal and oil pan to stop leakage. Tranny was dropped for this.
Following reassembly the transmission will not shift.
Found and replaced failed brakelight switch.
Still not shift.
Fluid levels are good.
Can't find anything impeding shifting.
I'm thinking the TCM lost it's mind.
Suggestions?
It won't upshift from first gear? If so, check to make sure your vehicle speed sensor is plugged in and wire not cut/frayed.
 

rockola1971

Full Access Member
Joined
Dec 29, 2016
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2,638
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3,588
Location
Indiana (formerly IL)
Replaced rear seal and oil pan to stop leakage. Tranny was dropped for this.
Following reassembly the transmission will not shift.
Found and replaced failed brakelight switch.
Still not shift.
Fluid levels are good.
Can't find anything impeding shifting.
I'm thinking the TCM lost it's mind.
Suggestions?
Need more info about this "tranny will not shift"? What do you mean? Wont mechanically shift into (D) or goes into gear but wont shift past 1st gear? Does manual 1 or 2 work? Did you get your shift cable properly attached to tranny and not get the adjustment out of wack at its adjuster?
 

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