Intermittent Problems

PRELIMINARY CHECKS

- Read PRELIMINARY CHECKS (READ BEFORE PROCEEDING)

- DO NOT use the diagnostic charts in Computers and Control Systems for intermittent problems. The fault message must be present to locate the problem. If a fault is intermittent, use of diagnostic charts may result in the replacement of good parts.


FAULTY ELECTRICAL CONNECTIONS OR WIRING

Most intermittent problems are caused by faulty electrical connections or wiring. Perform careful check of suspect circuits for:

- Poor mating of connector halves, or terminals, not fully seated in the connector body (backed out).

- Improperly formed or damaged terminals. All connector terminals in problem circuit should be replaced to insure proper contact tension.

- Poor terminal to wire connection. This requires removing the terminal from the connector body to check.


ROAD TEST

It is important to road test the vehicle to verify customer complaint.

- If a visual/physical check does not locate the cause of the problem, the vehicle may be driven with a voltmeter/scan tool connected to the suspect circuit. An abnormal voltage/scan reading, when the problem occurs, indicates a problem in that circuit.

- After the problem circuit has been isolated, check the wiring and connectors. If OK, test component/sensor. Repace if necessary

- Some scan tools have the ability to record sensor and data values in the "Snapshot" mode. This feature allows viewing of data over a time period before and after the problem occurs.