2013 Yukon XL Denali Slipping Out of Gear When Stopping

[allenjkmeier]

My 2013 Yukon XL Denali recently started slipping out of gear when coming to a complete stop at a red light, stop sign, etc. Once I let off the brake, it kicks back into gear but can take up to 3 seconds to do so. If I hit the gas prior to it kicking back into gear, it kicks in really hard.

I had the transmission fluid changed but that didn't seem to help. The vehicle has approximately 132k miles. In addition, the vehicle sputters a bit when the RPMs get too low--almost as if the vehicle doesn't downshift quickly enough. Depressing the gas pedal a bit more tends to alleviate the sputtering but, prior to having the issue with it dropping out of gear when stopping, this didn't happen.

A friend of mine hooked it up to a code reader (he's a mechanic), and there are no error codes whatsoever. Has anyone else had this issue? If so, was there a fix for it? Thank you in advance for any advice you could provide!

 

[larryderouin]

I had a 95 Jimmy (4/3Lv6 and 4L60E) that would do the same thing. That was the 1st indication the transmission was going and it got worse within 50miles (no 4th and 3rdup to 2500rpm). Within 75 miles it quit totally. I went to a salvage yard as a parts unit. Same thing (basically) with a 700R4 about 20 years prior in a '83 Blazer.

An Auto Transmission is a Hydraulics unit. Not enough or too much pressure in the circuits can cause weird or potentially fatal results for the tranny. Take it to a Transmission shop. Pulling the pan and changing the fluid isn't getting 1/2 the old fluid out. I usually get 20-25qts,(depending on the unit) take off the top tranny cooler line @ the Radiator and dump it into a 5 gallon can or 2 until the fluid runs clear and RED(about 15-18qts). Then I pull the pan, clean it, and replace the filter. Top it off, Run 3 minutes, shift to each gear for 15 seconds, and then check fluid and top off if needed.

The sputtering can be a lot of things, and most of them if triggered at least twice should light the S.E.S. Lamp. Have him look for random misfires, fuel pressures @ idle, Change the Fuel Filters (On the Frame rail and InTank). It could very well be the transmission is holding the current gear too long due to pressure on the solenoid either not being enough or a clogged orifice in the solenoids and lugging the engine down.

I now have a 2013 Yukon XL SLT with 273000 and on it's 2nd tranny. 1st went about 160,000. Put a 25000 GCWR rated Trans cooler on it, and haven't had tranny temps go above 150*F even pulling a 4500# trailer. Check for an Aux cooler on Front.

 

[allenjkmeier]

I sincerely appreciate the reply, Larry! When I had the transmission fluid flushed, he said he got 20 qts out so I assume he got everything out (but I'll check with him again to make sure). So, do you think the damage has already been done and I need to have the transmission rebuilt?