Diagnostic System Check - Automatic Transmission

Diagnostic System Check - Automatic Transmission

Test 1-6:

Test 7-12:

Description

Important: Do not perform the Diagnostic System Check-Automatic Transmission unless one of the concerns noted is present. Failure to follow this procedure could lead to misdiagnosis of the system.

The Diagnostic System Check-Automatic Transmission is an organized approach to identifying a condition created by an electronic transmission control system. The Diagnostic System Check-Automatic Transmission is intended for use in diagnosing a concern in a vehicle with separate engine and transmission control modules, ECM and TCM.

When an emission related Diagnostic Trouble Code (DTC) sets as a result of a transmission fault, the TCM requests the ECM to illuminate the Malfunction Indicator Lamp (MIL). This request will be identified by the ECM as DTC P0700. The ECM may also independently illuminate the MIL. Although either module may cause the MIL to illuminate, the scan tool can display DTCs from only one module at a time. In addition, the Clear DTC Info command clears DTC data from both modules. If the DTC failure records are not recorded from both modules before the DTC data is cleared, important diagnostic information will be erased.

Your training and experience as a technician may cause you to focus on either the TCM or the ECM, instead of both modules at the same time. To ensure that both modules are properly diagnosed, separate system checks are included. The Diagnostic System Check - Engine Controls identifies DTC status and communication function for the ECM. If no ECM DTCs are present, the Diagnostic System Check - Engine Controls will direct you to the Diagnostic System Check-Automatic Transmission.

The ECM diagnostics do not require transmission data in order to run. Correct use of the tables will reduce diagnostic time and prevent the replacement of good parts.

Diagnostic Aids
Inspect all of the related wiring and connections including the connections at the TCM, as these may cause an intermittent concern. Inspect the terminals for any damage or any corrosion. Inspect the connector for any pushed-out terminals.