The approved procedure for diagnosing all powertrain control system faults is included in the Strategy Based Diagnostic Flow in General Information. The preliminary checks and the Powertrain Onboard Diagnostic System Check must be performed to successfully diagnose and repair the powertrain systems.
Use a scan tool in order to read and clear diagnostic trouble codes.
Important: Use a scan tool in order to clear the diagnostic trouble codes from the PCM memory. Diagnostic trouble codes can also be cleared by turning off the ignition and disconnecting the battery power from the PCM for 30 seconds, but this method also causes all diagnostic information in the PCM memory to be cleared, and all of the diagnostic tests have to be re-run.
Since the PCM can have a failure which may affect only one circuit, following the approved diagnostic procedures determines which circuit has a problem and where the failure is. If a diagnostic table indicates that the PCM connections or the PCM is the cause of a problem and the PCM is replaced but the replacement does not correct the problem, one of the following conditions may exist:
| • | There is a problem with the PCM terminal connections. The diagnostic table indicates that the PCM connections or the PCM is the problem. The terminals may have to be removed from the PCM connector in order to inspect them properly. |
| • | The EEPROM program is not correct for the application. |
| • | Incorrect components may cause a malfunction and may or may not set a DTC. |
| • | The problem is intermittent. This means that the problem is not present at the time the system is being tested. In this case, refer to the Symptoms portion of the manual and make a careful visual and physical inspection of all suspected components and wiring associated with the affected system. |
| • | A shorted solenoid, relay coil, or harness. Solenoids and relays are turned on and off by the PCM using internal electronic switches called drivers. Each driver is part of a group of 7 called output driver modules. A shorted solenoid, relay coil, or harness does not damage the PCM but does cause the solenoid or relay to be inoperative. The J 34636 tester, or equivalent, provides a fast, accurate means of testing for a shorted coil or a short to battery voltage. |
