Diagnostic Aids

Check for the following conditions:

• An interruption of ground circuit or voltage supply to ignition coils will prevent a proper ignition event from taking place. DTC P1300 through P1315 will set if there is a fault in any ignition coil circuits.
• If DTCs P1305, P1310, and P1315 are present, fault is located in shared electrical circuits or shared components of ignition coils.
• Check ignition coil grounds at ground point G105 for a clean and tight connection.
• If no engine misfire is felt when DTC sets, check for a fault in Ignition Fail-Safe Input circuit. Check the noise filter for an internal short or low resistance. The ignition coil may not receive adequate voltage during high load conditions if noise filter is faulty. A good noise filter will indicate infinite resistance with a DMM after the capacitor inside the filter is charged up.
• Unless ignition key is cycled or DTCs are cleared, PCM waits to receive ignition fail-safe signals before providing fuel injector operation.

An intermittent malfunction may be caused by a fault in the ignition coil electrical circuit. Check wiring harness and related components for an intermittent condition. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 1.8L VIBE article. Repair any electrical circuit faults found. Information included in freeze frame data can be useful in determining vehicle operating conditions when DTC first set.