Weird shift from 1-2

[optimusprime]

2008 Yukon Denali with 220k on the clock. Recently I’ve been having some weird shifting going from 1st to 2nd. Happens exactly at 10mph at the first shift. It feels harsh and seems to stall slightly. After that everything else is normal. Ideas?

 

[Charlie207]

Mine used to do that after the first start of the morning, pulling out of my driveway,heading down a hill, but not up the hill in the other direction.

 

[optimusprime]

Mine is doing it 100% of the time.

 

[donjetman]

maybe TEHCM pressure switch(es) seals & membranes?

Transmission Codes P0842, P0872, P0877**UPDATE**

07 Denali w/6L80 tranny and has 191k miles, is shifting okay to me, but I borrowed a MAC Tools code reader and found codes for the tranny. So I think its time to replace the TEHCM pressure switches with seals & membranes, Sonnax kit # 124740-70K and Sonnax tool kit # 124740-TL70. @NickTransmissions

www.tahoeyukonforum.com

 

[NickTransmissions]

2008 Yukon Denali with 220k on the clock. Recently I’ve been having some weird shifting going from 1st to 2nd. Happens exactly at 10mph at the first shift. It feels harsh and seems to stall slightly. After that everything else is normal. Ideas?

Have you resolved the problem as of yet? If not, valve body: specifically 2-6 regulator valve, compensator feed valve or TCC regulator valve. Pump's TCC limit valve may also be excessively worn along with the main pressure regulator valve (very common in 6Ls)

 

[optimusprime]

took it to my local trans shot and he said it’s shot and needs to be replaced. I can’t remember what exactly he said but it was losing pressure in multiple areas? and throwing all sorts of codes. I’m just gonna write it off and get into something a little newer. Bums me out though. It’s been a good car. A little rough on the edges but went 220k with the worst thing being a coolant line blow up.