Important: 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:
| • | Poor mating of the connector halves or a terminal not fully seated
in the connector (backed out). |
| • | Improperly formed or damaged terminal. |
| • | All connector terminals in the problem circuit should be carefully
checked for proper contact tension. |
| • | 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 Tech 2
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. |
| • | Using a Scan Tool's 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. |
Loss of diagnostic code memory. To check, disconnect 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:
| • | Ignition coil shorted to ground and arcing at ignition wires
or plugs. |
| • | MIL (Service Engine Soon) wire to PCM shorted to ground. |
If the intermittent condition exists as a start and then stall , check
for DTCs relating to the vehicle theft deterrent system.
Check for improper installation of electrical options such as lights,
cellular phones etc. Route Ignition Control Module (ICM) 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 open diode across A/C compressor clutch and check for other
open diodes. Refer to
Wiring Repairs
in Wiring Systems.
