Humm, I wonder if it's a solenoid? Does it ever stall, has it set the CEL light?

 

go to a higher quality torque converter with a better lock up design .
Maybe even go so far as to use a controller lock up so you can lock it up at lower speeds
B&M makes a plug and play that would let you lock it up if I recall as low as 35mph .

Also as was suggested , you may have a solenoid issue. But those I have replaced , just completely failed all together or would lock , then a few seconds or minutes unlock , then lock back up . When that happens though you get the feel of it shifting down and up . If that’s happening you should also see it on your tach though

 

i would also think it would throw a trany code

 

No doesnt stall, no CEL light. Now that i know its TC related i actually found another post on the forum from someone that was exhbiting identical symptoms. I believe he ended up putting in a new TC.

Ill check out the B&M thanks for the direction.

 

Mine did the same thing,amaco added an additive to the fluid, it stopped the shuttering of going into overdrive,it works perfect now.....no more shuttering, the additive,LUBEGURD TRANS ADDITITVE, its $20.95 at Amazon.com,shipped


they suggested to add it in every year to keep fluid it tip-top running order......for all automatic transmissions,all makes



Rick H2/H3

 

interesting. ill give it a try. see if it does anything for me. do you know what version you used? when checking compatibility it comes back as incompatible with the hummer.