Re: Broken Wave Plate
Thanks SAILFISH! I had a broken wave plate problem with my 08 Enclave at 55k miles. The mechanic showed me a broken a wave plate he pulled out of a tranny the previous week. It looks just like the rings shown in your link above. The transmission wouldn't shift above third gear. I questioned the mechanic about the failure mode - he said that the transmission has speed sensors that measure the input and output speed of the transmission. This infomation is used by the Transmission Control Module to shift the transmission. The broken wave plate was brittle from heat and broke. What happens is - some metalic parts get attracted to the magnetic speed sensor, and blocks the speed sensor from working, so it won't shift properly. The broken wave plate seems to be the 3-5-R plate, with an engine code of P0716 among others.
To fix this - the transmission must be dropped, and disassembled. Broken metal parts have to be removed, the input speed sensor replaced, a new plate installed, and the transmission fluid lines including the transmittion cooler were flushed. I am not sure if there are filters in the transmission - my repair invoice did not list any filter changes. One recent post on this matter said there are no filters. Kind of strange I would think.
I don't belive this is a wide spread problem as not that many posts. However my dealer mechanic had fixed a few.........
2008 CXL FWD