| Subject: | Diagnostic Information on MH1, MN8, MT1, M15 Transmission Slips, Will Not Shift or May Overheat, SES/MIL May Be Illuminated, DTCs P0218, P0894 Set |
| Models: | 2006-2007 Buick Rendezvous, Terraza |
| 2006-2008 Buick LaCrosse, Lucerne, Allure (Canada Only) |
| 2006-2007 Chevrolet Avalanche 2500 Series, Malibu, Malibu SS, Malibu Maxx SS, Monte Carlo, Monte Carlo SS, Silverado Classic, Suburban |
| 2006-2008 Chevrolet Express, Impala, Impala SS, Uplander |
| 2006-2007 GMC Sierra Classic, Yukon XL 2500 Series |
| 2006-2008 Pontiac Grand Prix, Grand Prix GTP, G6, Montana SV6 |
| with HYDRA-MATIC® 4T80-E (MH1), 4T65-E (M15), 4L80E (RPO MT1) or 4L85E (RPO MN8) Automatic Transmission |
Notice: It is critical that all internal transmission components are thoroughly cleaned and the transmission cooler be flushed using the J 45096 transmission oil cooling system flush and flow test tool. It is also critical
that the system be flushed in both directions to capture any friction material trapped in the cooler. Be sure to back-flush first to push material out of the cooler, following the instructions provided with the J 45096.
The purpose of the bulletin is to provide technicians with additional diagnostic information on transmission slips, will not shift, or may overheat conditions. DTCs P0894 or P0218 may be set on the above transmissions.
These conditions may be caused by friction material debonding from the Torque Converter Clutch (TCC).
If any of these conditions are observed, the friction material from the TCC may have circulated throughout the transmission, the cooler lines, and the transmission cooler. Remove the transmission oil pan and inspect for friction material in the filter.
If friction material is observed in the trans pan or filter, the torque converter is the possible cause and it will be necessary to disassemble the transmission completely for a cost comparison (include a torque converter and filter in the estimate). Refer
to service bulletin 08-07-30-001 for cleaning and inspection instructions of the valve body assembly.
After the cost comparison, either repair or replace the transmission in the most cost effective way. If it is necessary to replace the transmission, contact the Product Quality Center (PQC) at 1-866-654-7654 per the most recent version of bulletin 02-07-30-029.
