Theory Of Operation

The Transmission Control Module (TCM) performs multiple self diagnostic test to validate proper operation. Memory is partitioned into three types; Random Access Memory (RAM), non-volatile data memory (NVM) and code memory. NVM and code memory is referred to as Read Only Memory (ROM).

RAM is used for temporary storage, although its contents may be retained with loss of power.

Non-volatile data memory is partitioned into battery independent and ignition independent non-volatile memories. These are memories that retain their contents without the supply of battery or ignition power once written to. They are tested or checksummed for data integrity. Code memory refers to the memory that contains boot, software and calibrations, and is unaltered except during reprogramming. Boot code memory is that portion of memory that contains code executed to bootstrap the system and provide communication and other interfaces needed to support reprogramming.