- Preliminary Information

OVERVIEW
The diagnostic charts and functional checks in this section are designed to locate a faulty circuit or component through logic based on the process of elimination. The charts are prepared with the requirement that the vehicle functioned correctly at the time of assembly and that there are no multiple failures.

DTC'S
The Transmission Control Module (TCM) performs a continual self-diagnosis on certain control functions. The TCM's language for communicating the source of a malfunction is a system of Diagnostic Trouble Codes (DTCs). There are two kinds of DTCs: a two-digit "flash code" DTC, and a four-digit OBD II DTC. When a malfunction is detected by the TCM, a "flash code" DTC is stored in the TCM, and an OBD II DTC is stored in the Engine Control Module (ECM). In addition, the TCM flashes the "OD/OFF" indicator lamp and ECM turns "ON" the "Service Engine Soon" Malfunction Indicator Lamp (MIL).