Intermittent Condition
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 to locate the problem.
Most intermittent problems are caused by faulty electrical connections
or wiring. Perform a careful visual/physical check for the following conditions:
| • | Inspect for poor mating of the connector halves or a terminal
not fully seated in the connector (backed out). |
| • | Check for improperly formed or damaged terminal. |
| • | Inspect all connector terminals in the problem circuit should
be carefully checked for proper contact tension. |
| • | Inspect for poor terminal to wire connection. This requires removing
the terminal from the connector body to check. |
Road test the vehicle with a J 39200 Digital Multimeter connected
to a suspected circuit. An abnormal voltage when malfunction occurs is a good
indication that there is a fault in the circuit being monitored.
Use a scan tool to help detect intermittent conditions. The scan tool
has several features that can be used to locate an intermittent condition.
Use the following features to find intermittent faults:
| • | The Snapshot feature can be triggered to capture and store engine
parameters within the scan tool when the malfunction occurs. This stored information
then can be reviewed by the service technician to see what caused
the malfunction. |
| • | A scan tool Freeze Frame data or Failure Records data can also
aid in locating an intermittent condition. Review and record the
information in the freeze frame or failure record associated with the
intermittent DTC being diagnosed. The vehicle can be driven within
the conditions that were present when the DTC originally set. |
Check for a loss of diagnostic code memory. To check, disconnect the
MAP sensor and idle engine until the MIL (Service Engine Soon) comes ON. DTC P0107
should be stored and kept in memory when ignition is turned OFF.
If not the PCM is faulty. When this test is completed, make sure
that you clear the DTC P0107 from memory.
An intermittent MIL (Service Engine Soon) with no stored DTC may be
caused by the following:
| • | Inspect the ignition coil shorted to ground and arcing at ignition
wires or spark plugs. |
| • | Check the MIL (Service Engine Soon) wire to PCM shorted to ground. |
Check for improper installation of electrical options such as lights,
cellular phones etc. Route Ignition Control (IC) Module wiring away from secondary
ignition wires and ignition coils . Check all wires from the PCM
to the ignition control module for poor connections.
Check for an open diode across the A/C compressor clutch and check
for other open diodes. Refer to wiring diagrams in
Engine Controls Schematics
.
