2011 silverado help with transmission

newdude · January 3, 2022

On 1/2/2022 at 7:26 AM, chiri said:

Thanks for your answers, already did a scan but with a very basic scanner, will look for a more capable scanner. I am no expert and have no experience with AT, but the continuos RPM fluctuations seems more as a electronic issue more than mechanic failure, or can it be that the computer activates the TQ lock, detects something wrong and disconnect and then starts cycling?

Sorry if this is a silly question, just want to try to understand more of this

If its an erratic slip that goes from 0-100+ rpm, the trans needs to come out. Converter is gone which explains the high RPM slips. Lockup clutch inside it is toast, probably much more in the trans. If the converter failsbad enough, the trans has been pumping all that clutch plate material throughout the transmission and killing the rest of it.

She needs to come out and be torn apart. Pan dropped to inspect for the magnet full of clutch materials and possibly metals. Pump must be inspected for wear, 4-5-6 clutch inspected for wear. If you are really seeing up to 200rpm slips, I'm surprised the trans hasn't set a P0741 converter lock up off code.

Healthy torque converter should slip no more than 0-20rpm. A near steady 60rpm slip speed and a fish bite or shutter is bad fluid.

Edited January 3, 2022 by newdude

Supreme Pizza · January 3, 2022

16 minutes ago, newdude said:

If its an erratic slip that goes from 0-100+ rpm, the trans needs to come out. Converter is gone which explains the high RPM slips. Lockup clutch inside it is toast, probably much more in the trans. If the converter failsbad enough, the trans has been pumping all that clutch plate material throughout the transmission and killing the rest of it.

She needs to come out and be torn apart. Pan dropped to inspect for the magnet full of clutch materials and possibly metals. Pump must be inspected for wear, 4-5-6 clutch inspected for wear. If you are really seeing up to 200rpm slips, I'm surprised the trans hasn't set a P0741 converter lock up off code.

Healthy torque converter should slip no more than 0-20rpm. A near steady 60rpm slip speed and a fish bite or shutter is bad fluid.

A lot of people don't flush the lines / coolers after the trans fails. Then they install a new transmission and torque converter, and pump all that crap through the new transmission.

I know a guy that had a bad transmission, and after installing the new one, it failed after 1 day. He did not replace or flush the cooler, which was full of debris from the failed trans.

Ben Albright · January 4, 2022

I had this same issue with my wife's Tahoe. Torque converter would lock up and bounce the rpms (100-200) while driving on flat ground with the cruise control set. Dropped the pan and cleaned and installed a new filter and fluid, same thing. Nothing on the scanner as far as codes. Called dealership and it was out of warranty by a month so I rationalized that the converter was toasted and not holding lockup. My theory was correct and a new torque converter was the fix with another filter and fluid.

swathdiver · January 6, 2022

On 1/3/2022 at 3:24 PM, chiri said:

Just in case, any recommendation as a source of remanufactured transmissions?

Your local GM dealership will have them available with a 100K mile warranty, I think they are new and not remans.

Precision Transmission in Amarillo, Texas does good work.

swillson1980 · January 18, 2022

OP My 2012 sierra had this very problem 2 months ago and evolved into completely coming out of gear and revving up like its in neutral while in overdrive trying to accelerate from a stop light. currently at transmission shop for new torque converter/rebuild. Also developed a small oil leak so they are replacing the rear main seal as well.