- Powertrain/On-Board Diagnostic System Check

Diagnostic Chart:

Wiring Diagram:

Circuit Description

The Powertrain On-Board Diagnostic System Check must be the starting point for any driveability complaint diagnosis. Before using this procedure, you should perform a careful visual/physical check of the PCM and engine grounds for being clean and tight.

The Powertrain On-Board Diagnostic System Check is an organized approach to identifying a problem created by an electronic engine control system malfunction.


Diagnostic Aids

An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside the insulation. Check for poor connections or a damaged harness. Inspect the PCM harness and connectors for improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection, and damaged harness.

Test Description

Number(s) below refer to the Step number(s) on the Diagnostic Chart:

1. The Malfunction Indicator Lamp (MIL) should be ON steady with the key ON/engine OFF. If not, refer to No Malfunction Indicator Lamp. Testing and Inspection

2. This test ensures that the PCM is capable transmitting Class 2 serial data to the DLC and that the Class 2 data circuit is not open or shorted. If a DLC problem exists, refer to the Data Link Connector Diagnosis. Testing and Inspection

3. If the engine will not start, refer to the Engine Cranks but Does Not Run. Testing and Inspection

4. The scan tool may display DTC(s) which are diagnosed in 4T60-E Automatic Transaxle Diagnosis. Refer to the PCM Diagnostic Trouble Codes table for a complete list of DTC(s) supported by this vehicle application. Testing and Inspection

6. A scan tool parameter which is not within the typical range may help to isolate the area which is causing the problem.