Transmission Confused and Low Frequency Rumble 42 MPH in V4

[15GMCSierra]

I searched the forums, but could not find these particular issues. If they exist, please post the link. The main transmission topics did not seem to fall in this category.

 

1. Transmission is confused on an incline on the 1-2 shift on my driveway (about 6 degree grade) and on the 2-3 shift (4-5 degree grade) between 20 and 30 MPH. The RPM drops from about 2000 down to 1200 after the shift and stutters/shudders, stalls, etc. The RPM fluctuates up and down when it happens about 50-100 RPM. It clears up after the next shift.

 

2. I am getting a low frequency rumble in the cab in v4 mod, flat ground with the cruise control set at 42 MPH.

 

I have 950 miles on the truck. I purchased it with 380 miles. I would expect any transmission learning process has already occurred by now. Thanks for the help.

[galliher_nc]

GM claims the "learning process" takes up to 5,000 miles and won't do anything for you until then.

[redwngr]

Which eng/trans?

[CounterMeasure]

GM claims the "learning process" takes up to 5,000 miles and won't do anything for you until then.

 

Interestingly enough, rep from GM told me it was 1800 miles. Either case, OP, you need to put some miles on it to see what it settles into.

[15GMCSierra]

Which eng/trans?

Thanks. I updated my signature. 5.3L EcoTech (Non-FFV) and 3.42 gears. I will wait a little longer for the learning process. I do not believe the low frequency rumble is transmission related.

[black00ta]

I had this problem and mine really settled down around 3k miles, its still there but very minor now.