Diagnosis & Testing: Introduction

PCM continuously monitors transmission operation and contains a self-diagnostic system which stores a Diagnostic Trouble Code (DTC) if an electronic control system problem or component failure is present. A 4-digit OBD-II DTC is used in the self-diagnostic system for diagnosis. DTC is stored in PCM and illuminates Malfunction Indicator Light (MIL) when set. If OD/OFF indicator or MIL indicates a system malfunction, retrieve DTC using desired method. See RETRIEVING DIAGNOSTIC TROUBLE CODES  .