A problem may or may not turn ON the Malfunction Indicator
Lamp (MIL) or store a DTC. DO NOT use the Diagnostic Trouble Code (DTC) charts
for intermittent problems. The fault must be present in order to locate
the problem.
Most intermittent problems are caused by faulty electrical connections
or by faulty wiring. Carefully inspect for the following conditions:
| • | Poor mating of the connector halve, or a terminal that is not
fully seated in the connector |
| • | Improperly-formed or damaged terminals |
| • | Proper contact tension at all connector terminals in the problem
circuit |
| • | Poor terminal to wire connection--Remove the terminal from
the connector body in order to check the connections. |
Road test the vehicle with a Digital Multimeter that is connected to
a suspected circuit. An abnormal voltage when malfunction occurs is a good
indication that there is a fault in the circuit that is being monitored.
Use a scan tool in order to help detect any intermittent conditions.
The scan tool has several features that can be used to locate an intermittent
condition. Use the following features in order to find the intermittent
faults:
| • | Use the Snapshot feature in order to capture and to store the
engine parameters within the scan tool when the malfunction occurs. The service
technician than can review the stored information in order to see what caused
the malfunction. |
| • | Use the Freeze Frame data or the Failure Records data in order
to help to locate an intermittent condition. Review and record the information
in the Freeze Frame or the Failure Record that is associated with the intermittent
DTC that you are diagnosing. Drive the vehicle within the conditions that
were present when the DTC originally set. |
Test the vehicle for loss of diagnostic code memory. Disconnect the
manifold absolute pressure (MAP) sensor, and idle the engine until the MIL
turns ON. When the ignition is turned OFF, DTC P0107 should be
stored and kept in memory. If this does not occur, the PCM is faulty.
When you complete this test, clear DTC P0107 from the scan tool memory.
An intermittent MIL (Service Engine Soon) with no stored DTC may be
caused by the following conditions:
| • | An ignition coil that is shorted to ground and arcing at the
ignition wires or at the plugs |
| • | A MIL wire to the PCM that is shorted to ground |
Inspect for improper installation of the electrical options such as
the lights, the cellular phones, and other optional equipment. Route the ignition
control (IC) module wiring away from the secondary ignition wires and
the ignition coils. Inspect all the wires from the PCM to the ignition
control module for poor connections.
Test for an open diode across the A/C compressor clutch, and test for
other open diodes. Refer to
Wiring Repairs
in
Wiring Systems.
