Refer to
PCM Power, Grounds, MIL Control, Serial Data
.
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:
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The MIL should be ON steady with the key ON/engine OFF. If not, refer to Malfunction Indicator Lamp (MIL) Inoperative .
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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 .
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If the engine will not start, refer to the Engine Cranks but Does Not Run .
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The scan tool may display DTC(s) which are diagnosed in 4T60-E Automatic Transaxle Diagnosis, Section 7. Refer to the PCM Diagnostic Trouble Codes table for a complete list of DTC(s) supported by this vehicle application.
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The scan tool may display DTC(s) which are diagnosed in 4T60-E Automatic Transaxle Diagnosis, Section 7. Refer to the PCM Diagnostic Trouble Codes table for a complete list of DTC(s) supported by this vehicle application.
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A scan tool parameter which is not within the typical range may help to isolate the area which is causing the problem.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Is the MIL ON? | -- | Go to Malfunction Indicator Lamp (MIL) Inoperative | ||
Does the scan tool display PCM data? | -- | Go to Data Link Connector Diagnosis | ||
Attempt to start the engine. Did the engine start and continue to run? | -- | Go to Engine Cranks but Does Not Run | ||
Display DTC Info Last Tst Fail. If any DTCs are stored as last test failed, save the freeze frame and fail record information using the Capture Info feature on the scan tool. Are any DTCs indicated as last test failed? | -- | Go to applicable DTC table | ||
Display DTC Fail Records with the scan tool. If any DTC Fail Records are stored, save the freeze frame and fail record information using the Capture Info feature on the scan tool. Are any Fail Records stored? | -- | Go to applicable DTC table | ||
Compare PCM data values displayed on the scan tool to the typical engine scan data values. Are the displayed values normal or close to the typical values? | -- | No trouble found | Refer to indicated Component System Checks |
