I'm having issues with my yukon XL and was curious if anyone could help.

It's a 3/4 ton with the 6.0l and my torque converter's not locking up. Every once in a while it shifts really hard to the next gear as if it's got a shift kit, slip slightly, or kind of jerk like it's engaging the next gear before the previous gear was disengaged. Again, it only does this on rare occasion, it shifts normally probably 95% of the time.

I can feel it start to lock up the torque converter, but it feels like it slips and never locks. When cruising and it goes to OD, if I put it under a mild load (not enough to down gear) I can feel it slip in and out over and over like ever second, like it's trying to lock & unlock the torque converter.

I checked all fuses, no CEL, try tow/haul on and off, and the only thing it changes is shift points. Fluid looks clean, smells fresh, and is full.

Any ideas?

~Luke
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1969 Cougar - 11.91 - 380HP
2007 GSXR 750
1999 OZ - SOLD - 15.26 NA - 14.71 on 75 shot

Welcome, indeed I am the GM tech. Paypal me my $93 hour diag and I shall help you son.

















Payment recieved, thank you sir

You could possibly have a bad valve body, they are common.
We also see a lot of bad shift solenoids too.
However, I do not do a lot of Trans work, because we have one guy that is just awesome. If you want, You can call me tomorrow, and I can let you talk to our trans guy over the phone so he can give you some pointers to check out if you would like. He is old, lol, but he knows his shit granted, he has been in the trans. game for a LONG LONG time. PM me and I shall give you my cell #.

-MIKE-

Stroked 2.2L

lets face it....Mike doesnt do trans work becasue he gets confused by the term valvebody.

for 93.00 that info blows...i would fire your ass.

I know the late model auto trannys had a lot of issues with shift solinoids. The 4L60E was terrible for shit like that. Most trans shops I have talked with are free diagnosis or its only 30 min cost of 40.00. Usually they have an idea over the phone. Sounds to me liek the lockup solinoid might be acting up but I dont know auto-trannys that well.