| June 28, 2017

The way jargon, abbreviations and acronyms get tossed around in technical discussions, it’s easy to talk about things without truly understanding them.

Take transmission components. There’s plenty of talk about TCM (Transmission Control Module) and TEHCM (Transmission Electro-Hydraulic Control Module), but what is the significance of each and the key differences?

Simple answer: They’re actually quite similar. Both process vehicle information and trigger responses designed to provide optimal shift points.

Where they differ is in location, complexity and associated type of transmission. The TCM sits on the outside of GM 8-Speed transmission. The TCM incorporates more aluminum and magnesium components, saving 8 lbs. of weight compared to a TEHCM.

The TEHCM, meanwhile, is an internal component on GM 6-Speeds, including the 6T30/40/45/50, 6T70/75, 6T80, 6L45/50, 6L80 and 6L90. The TEHCM combines the function of a TCM with valve body solenoids, integrated electronic and hydraulic components, pressure and temperature switches, filter plate and an upgraded lead frame — all in a single unit.
Each control module offers its own advantages. Because it is external, the TCM is easier to work on. “Shops don’t always have to reprogram it after a repair,” says GM Product Specialist, Michelle Francisco.

The TEHCM consolidates the functions of four or five separate units into one, following an industry engineering trend of having fewer parts handling more duties. Both modules also share some other key benefits. When they’re built by GM, they arrive tested and ready to go to work. They’re backed by warranties and support from GM’s network of parts dealers and technical experts.
Knowledge will help your shop continue navigating the sometimes murky waters of our industry.

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Category: The Technical Side