Intermittents

INTERMITTENTS CHECK PROCEDURES
- Problem may or may not turn "on" the Malfunction Indicator Lamp (MIL) or store a Diagnostic Trouble Code (DTC).
- Intermittent means that MIL comes on at times, but does not stay on.
- If the trouble is found to be an "Intermittent" when using the "DTC Chart", refer to this procedure to locate the problem.
- If a fault is intermittent, use of DTC Charts may result in replacement of good parts.
- Most intermittent problems are caused by faulty electrical connections or wiring. Perform the careful checks as described below.
a. Check for poor mating of the Connector halves, or terminals not fully seated in the Connector Body (backed out).
b. Check for improperly formed or damaged Terminals. All Connector Terminals in problem Circuit should be carefully reformed to increase contact tension.
c. Check for poor Terminal to wire connection. This requires removing the Terminal from the Connector Body to check.
d. Check for poor ground connections.
e. If a visual check does not find the cause of the problem, the car can be driven with a Digital Multimeter connected to a suspected Circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that Circuit.

- An intermittent MIL with no stored DTC may be caused by;
- Ignition Coil to ground and arcing at Spark Plug Wires or Plugs.
- Main Relay which is in Power Supply Circuit is faulty.
- Poor matings of Power Supply Circuits connections.
- MIL wire to ECM shorted to ground (circuit 10).
- Diagnostic "Test" Terminal wire to ECM, shorted to ground (circuit 8).
- ECM power grounds are poor connected to Intake Manifold. See ECM wiring diagrams.
- Check for an electrical system interference caused by a defective relay, ECM driven Solenoid, or Switch. They can cause a sharp electrical surge. Normally, the problem will occur when the faulty component is operated.
- Check for improper installation of electrical options, such as lights, etc.