O/D Off Indicator Light

The ECM provides emission-related On-Board Diagnostic (OBD-II) functions for A/T system. One function provided by ECM is to receive a signal from TCM when A/T faults are OBD-II related. These faults are indicated by MIL. The TCM self-diagnostic procedure is performed to confirm faults communicated to ECM from TCM and to check other A/T related concerns. The O/D OFF indicator light is used to display TCM flash codes (judgement flickers). Always perform TCM SELF-DIAGNOSTIC PROCEDURE  after DTCs have been retrieved using MIL or scan tool.