The approved procedure for diagnosing all powertrain control
system faults is included in the Strategy Based Diagnostic Flow . The
preliminary checks and the Powertrain Onboard Diagnostic System Check
must be performed to sucessfully diagnose and repair the powertrain systems.
To read and clear diagnostic trouble codes, use a scan tool.
Important: 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.
Since the PCM can have a failure which may affect only one circuit,
following the approved diagnostic procedures will determine which circuit
has a problem and where it is. If a diagnostic table 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 conditions may
exist:
• | There is a problem with the PCM terminal connections. The diagnostic
table will indicate that the PCM connections or PCM is the problem. The terminals
may have to be removed from the PCM connector in order to check 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 checked. In this case, refer to
Symptoms
and make a careful visual and physical
inspection of all suspected components and wiring associated with the
affected system. |
• | 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. |