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HOMESERVICE MANUALSGMC2010SAVANA G2500, VAN CARGO EXTENDED, 6.6 6REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 29 (AUTOMATIC TRANSMISSION - ALLISON - DIAGNOSIS)DESCRIPTION & OPERATIONELECTRONIC COMPONENT DESCRIPTIONTRANSMISSION CONTROL MODULE
2010 GMC Savana G2500, Van Cargo Extended, 6.6 6

Transmission Control Module

2010 GMC Savana G2500, Van Cargo Extended, 6.6 6SECTION Transmission Control Module
WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Silverado, and 2003 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

A microcomputer controls the transmission by receiving and processing signals from various switches and sensors. The microcomputer determines shift sequences, shift timing, and clutch apply and release characteristics. The microcomputer is an independent controller and is referred to as the Transmission Control Module (TCM). See Fig 1. TCMs are available in 12-volt configurations to match the configuration of the vehicle electrical system. The pressure switch manifold and Park/Neutral Position (PNP) switch provide operator input to the TCM. Other data sent to the TCM include throttle position; engine, turbine, and output speeds; and sump temperature. Any active special function, such as anti-lock brakes or power takeoff, is also an input to the TCM. The TCM processes this data to determine proper shift points, to monitor the current gear range, to perform ratio tests, and to compile diagnostic data. The TCM is programmed to protect the transmission and other vehicle driveline components by inhibiting actions such as full-throttle shifts from Neutral and high-speed direction changes. The TCM determines if a system malfunction exists and stores Diagnostic Trouble Codes (DTC) related to the malfunction. The codes, accessed by the service technician, are used in diagnosing persistent or intermittent trouble in the system.

Fig 1: Identifying Transmission Control Module
G00090767Courtesy of GENERAL MOTORS CORP.
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