Century V6-3100 3.1L VIN M SFI (1998)
Engine Control Module: Initial Inspection and Diagnostic Overview
To read and clear diagnostic trouble codes, use a scan tool.
Use a scan tool to clear 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 will also cause all diagnostic information in the PCM memory to be
cleared and all the diagnostic tests will have to be re-run.
The Vehicle Identification Number (VIN) is programmed into the PCM. Do not exchange a PCM from another vehicle for testing or replacement. When
replacing the PCM, the VIN must also be programmed into the new PCM.
Because the PCM can have a failure which may affect only one circuit, follow the diagnostic procedures in Computers and Control Systems / System
Diagnosis to determine which circuit has a problem and where it is.
If a diagnostic chart indicates that the PCM connections or PCM is the cause of a problem and the PCM is replaced, but does not correct the problem,
one of the following may be the reason:
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There is a problem with the PCM terminal connections. The diagnostic chart will say PCM connections or PCM. The terminals may have to be
removed from the connector in order to check them properly.
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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 checked. In this case, refer to the
Symptoms portion and make a careful physical inspection of all components and wiring associated with the affected system. See: Powertrain
Management/Computers and Control Systems/Testing and Inspection
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There is 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 seven called Output Driver Modules. A shorted solenoid, relay coil, or harness will not damage
the PCM but will cause the solenoid or relay to be inoperative. The J 34636 tester, or equivalent, provides a fast, accurate means of checking
for a shorted coil or a short to battery voltage.
