Diagnostic Aids

If no problems are found in fuel pump circuit or ignition system, check for the following conditions:

• Faulty fuel injectors.
• Faulty anti-theft system.
• Fouled spark plugs.
• EGR valve stuck open.
• Water in fuel system.
• Grounded ignition control signal circuit.
• Restricted exhaust system.

Check ignition system for grounded tachometer circuit, worn distributor cap or worn distributor rotor. Check ignition wires by lightly spraying them with water in order to identify intermittent no-starts. Check for incorrect valve timing, loose or broken timing chain, low compression, worn camshaft lobes, or bent or burned intake or exhaust valves.

The VCM incorporates integrated circuits that are fault protected, therefore, if a circuit has failed, the integrated circuit may not be damaged. If this is the case, the system will keep the faulty circuit open until the condition has been corrected. Afterwards, reconnect the VCM and check the circuit. Replace VCM only if circuit is still inoperative.

An intermittent may be caused by a poor connection, rubbed through wire insulation or broken wires inside their insulation. Thoroughly check any circuitry suspected of causing an intermittent complaint. See appropriate TROUBLE SHOOTING - NO CODES article.