This is an excellent Technical White Paper … a worthy write up on the GM Torque Converter describing in great detail its design… how it functions ...and how to diagnose problems with the TC for problems under varying Test Conditions using non-exotic Tools:
https://www.thoughtco.com/diagnosing-gm-converter-lock-up-problems-262653
...and this link covers testing under “Braking to Stall” conditions that should only be considered after completely understanding which type of Transmission is in the vehicle and what the Real Risks for damaging it are if these tactics are not correctly performed:
https://auto.howstuffworks.com/under-the-hood/vehicle-maintenance/how-to-test-torque-converter.htm
And equally interesting and useful as a ready reference to locate the correct Torque Converter for the GM 4L60E / 4L65E / 4L70E Transmissions by their Factory Four Alpha Code Designations for your particular Transmission (The White Sticker on the Top of the Transmission Case) … this site will prove very edifying:
https://www.transtar1.com/products/torque-converters/product-info/4L60E-4L65E-4L70E-Torque-Converter
https://www.thoughtco.com/diagnosing-gm-converter-lock-up-problems-262653
...and this link covers testing under “Braking to Stall” conditions that should only be considered after completely understanding which type of Transmission is in the vehicle and what the Real Risks for damaging it are if these tactics are not correctly performed:
https://auto.howstuffworks.com/under-the-hood/vehicle-maintenance/how-to-test-torque-converter.htm
And equally interesting and useful as a ready reference to locate the correct Torque Converter for the GM 4L60E / 4L65E / 4L70E Transmissions by their Factory Four Alpha Code Designations for your particular Transmission (The White Sticker on the Top of the Transmission Case) … this site will prove very edifying:
https://www.transtar1.com/products/torque-converters/product-info/4L60E-4L65E-4L70E-Torque-Converter
