Intermittent Failures

A diagnostic trouble code that is not there every time the PCM checks the circuit is an intermittent DTC. Most intermittent DTCs are caused by wiring or connector problems. Defects that come and go like this are the most difficult to diagnose, they must be looked for under specific conditions that cause them. The following checks may assist you in identifying a possible intermittent problem.

• Visually inspect related wire harness connectors.
• Look for broken, bent, pushed out, or corroded terminals.
• Visually inspect the related harnesses.
• Look for chafed, pierced, or partially broken wire.
• Refer to any technical service bulletins that may apply.
• Use the DRBIII® scan tool data recorder or co-pilot.

Intermittent failures may cause Malfunction Indicator Light (MIL) to flicker or illuminate and go out after intermittent failure goes away. However, the corresponding Diagnostic Trouble Code (DTC) will be retained in Powertrain Control Module (PCM) memory. If related failure does not reoccur within 40 warm-up cycles, related DTC will be erased from PCM memory. Most intermittent failures are caused by a sensor, electrical connector or wiring related problems. See INTERMITTENTS in appropriate TROUBLE SHOOTING - NO CODES article.