Diagnostic Aids

If operation of ignition system is intermittent, check for a reliable reference signal from CMP sensor while cranking engine. PCM relies on CMP sensor for engine reference. Without continuous accurate reference signals, there is no reliable spark or fuel injector pulse. The scan tool engine speed display should be more than 200 RPM while cranking. If erratic values, such as sudden spikes in engine speed are displayed, engine reference signal may not be stable enough for engine to start and run properly. Inspect CMP sensor signal circuit for Electromagnetic Interference (EMI) or poor electrical connections.

A vehicle that starts and runs after being brought to the shop for an engine cranks but will not run concern, may have an ignition system that is susceptible to moisture. Spray water on ignition system components and wiring in order to check for an engine miss or stall. An intermittent malfunction may be caused by a problem in ignition system electrical circuit. Inspect wiring harness and components for an intermittent condition. See INTERMITTENTS in TROUBLE SHOOTING NO-CODES - 2.0L & 2.5L TRACKER article.