Testing For Intermittent Conditions

Intermittent Conditions
If the Tech 2 displays a diagnostic trouble code as intermittent, or if after a test drive a DTC does not reappear though the detection conditions for this DTC are present, the problem is most likely a faulty electrical connection or loose wiring. Terminals and grounds should always be the prime suspect. Intermittents rarely occur inside sophisticated electronic components such as the PCM.
Use the DTC information to understand which wires and sensors are involved.
When an intermittent problem is encountered, check suspect circuits for:
1. Poor terminal to wire connection.
2. Terminals not fully seated in the connector body (backed out).
3. Improperly formed or damaged terminals.
4. Loose, dirty, or corroded ground connections:

HINT: Any time you have an intermittent in more than one circuit, check whether the circuits share a common ground connection.

5. Pinched or damaged wires.
6. Electro-Magnetic Interference (EMI):

HINT: Check that all wires are properly routed away from spark plug wires, distributor wires, coil, and generator. Also check for improperly installed electrical options, such as lights, 2-way radios, etc.

Use the F2 SNAPSHOT mode of the Tech 2 to help isolate the cause of an intermittent fault. The snapshot mode will record information before and after the problem occurs. Set the snapshot to "trigger" on the suspect DTC. If you notice the reported symptom during the test drive, trigger the snapshot manually.
After the snapshot has been triggered, command the Tech 2 to play back the flow of data recorded from each of the various sensors. Signs of an intermittent fault in a sensor circuit are sudden unexplainable jump in data values out of the normal range.

Transmission And PCM Identification





The chart contains a list of all important information concerning rear axle ratio, Powertrain Control Module (PCM), and transmission identification.