DEFINITION: The problem is not currently present but is indicated in DTC History.

OR

There is a customer complaint, but the symptom can not currently be duplicated (if the problem is not DTC related).

Many intermittent open or shorted circuits come and go with harness/connector movement caused by vibration, engine torque, bumps/rough pavement, etc.. Inspect for this type of condition by performing the applicable procedure from the following list:

If the harness or connector movement affects the data displayed, component/system operation, or engine operation, inspect and repair the harness/connections as necessary. Refer to Electrical Connections or Wiring in this table.

Freeze Frame/Failure Records data (where applicable) can be used to duplicate the conditions under which a DTC sets.

1. Review and record the Freeze Frame/Failure Records data.
2. Clear the DTCs using the scan tool.
3. Turn the key to OFF and wait 15 seconds.
4. Operate the vehicle under the same conditions that were noted in the Freeze Frame/Failure Records data (as closely as possible). The vehicle must also be operating within the conditions for running the DTC. Refer to Conditions for Running the DTC.
5. Monitor DTC Status for the DTC being tested. The scan tool will indicate Ran, when the enabling conditions have been satisfied long enough for the DTC to run. The scan tool will also indicate whether the DTC passed or failed.

An alternate method is to drive the vehicle with a DMM connected to a suspected circuit. An abnormal reading on the DMM, when the problem occurs, may help you locate the problem.

The scan tool can be set up to take a snapshot of the parameters available via serial data. The Snapshot function records live data over a period of time. The recorded data can be played back and analyzed. The scan tool can also graph parameters singly or in combinations of parameters for comparison. The snapshot can be triggered manually at the time the symptom is noticed, or set up in advance to trigger when a DTC sets.

An abnormal value captured in the recorded data may point to a system or component that needs to be investigated further.

Refer to the scan tool user instructions for more information on the Snapshot function.

Poor electrical connections/terminal tension or wiring problems cause most intermittent problems. Perform a careful inspection of the suspected circuit for the following:

Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

The following conditions may cause an intermittent MIL and no DTCs:

If the MIL can be commanded on and off with the scan tool, none of the above conditions are present, and no DTCs are set, re-program the PCM with the most current calibration software and recheck MIL operation. Refer to Powertrain Control Module Replacement/Programming .

In order to test for loss of DTC memory, perform the following test:

1. Disconnect the engine coolant temperature (ECT) sensor.
2. Start the engine.
3. Monitor the DTC status for DTC P0118 using a scan tool.
4. Allow the engine to idle until the DTC P0118 diagnostic runs and fails.
5. Turn the key to OFF and wait at least 30 seconds.
6. Turn the key to Run.
7. Monitor the scan tool for DTCs.

The scan tool should indicate DTC P0118 Failed Since Code Clear. The PCM should store and retain this information in memory even after turning off the ignition for at least 30 seconds (the information should be stored indefinitely as long as the PCM battery feed and ground circuits are uninterrupted). If the DTC info is not retained, and the PCM power and grounds are OK, the PCM is malfunctioning.

Test for an open diode across the A/C compressor clutch and for other open diodes.

Inspect for improper installation of non-factory (aftermarket) add on accessories such as lights, 2-way radios, electric motors, etc..

Test the generator for a bad rectifier bridge that may be allowing A/C noise into the electrical system. Refer to Diagnostic System Check - Engine Electrical in Engine Electrical.