GM 6L80 Transmissions – How to Rebuild & Modify

As modern vehicles become ever more complicated and sophisticated it’s no wonder that so few people are prepared to work on their vehicles, as they would have done years ago. Nevertheless, some areas of automotive maintenance have always been seen as a black art, tasks best left to the professional specialists. Of these, the most obvious is automatic transmissions. How do they work? What, if anything, in the way of maintenance and/ or repair can the enthusiast undertake? How has the technology developed over the years as cars become ever more computerised and reliant on sensitive electronics?

Well, it seems that you can take on much of the work that the professional will accomplish, as long as you have the right instructions and the necessary tools to carry out the work. That’s not to say that the average car enthusiast can become an overnight expert, but reasonably skilled mechanics with a clean, orderly workshop and a certain amount of savvy should be able to accomplish a fair bit, given the right information.

We’ve reviewed a number of ‘workbench how-to’ manuals on automatic transmission from Car Tech over the years. This latest one features the General Motors 6L80, which dates from 2006 and has been installed in a wide range of GM vehicles since then, as well as those of other manufacturers which GM has supplied. This ‘how-to’ claims to take much of the guesswork out of the process of repair and maintenance by breaking down the tasks into basic elements. As with all books in this series the easy-to-read text is supported by many full colour photographs which help to demonstrate what is required.

Four chapters deal with the fundamental aspects of the transmission. The first explains the basics about the 6L80, the principles of how it works, the tools one will need, how to inspect the unit, identify what it is and test its functionality and what adhesives, sealers and lubricants will be required. Chapter two deals with the mechanical electronic components. Chapter three explains about component service, disassembly and assembly and chapter four concentrates on TEHCM inspection and testing. TEHCM stands for Transmission Electrical Hydraulic Control Module, which is essentially the ‘brain’ containing the hydraulic solenoids, temperature sensor, pressure switches and the transmission computer. In addition, there are coloured flow charts in the extensive Appendix. I will happily admit to it being all gobbledegook to me, but then I’m no mechanic and I’ll be content to leave it to them. However, for the technically minded, this could be a real godsend.