Chart 5

Unique Idle Concerns:

Fast Idle

Additional Driveability Concerns:

Diesels/Runs On

NOTE: If vehicle runs normally after the ignition key is turned OFF, check for damaged ignition switch, IGN RUN circuit short to power, VPWR circuit short to power, etc. Refer to the appropriate SYSTEM WIRING DIAGRAMS article.

SYSTEM/COMPONENT	REFERENCE ( PINPOINT TEST - CNG, FLEX-FUEL & GASOLINE ) unless noted
Base engine air leaks, including proper sealing of intake manifold and components/vacuum lines attached to intake air (such as the PCV, EGR or IAC valve/vacuum lines).	Visual, Engine System - Refer to the appropriate ENGINE article.
Verify engine operates at normal temperature.	Visual (refer to STEP 2: NO DTC(S) PRESENT SYMPTOM CHART INDEX or the appropriate ENGINE COOLING article, to diagnose any cooling system concerns that are present).
Fast idle concerns: Key on, engine off, monitor TP MODE PID while wiggling TP sensor circuits. TP MODE PID can also be monitored during vehicle drive. With throttle closed, TP MODE PID must be C/T (closed throttle).	TP Mode PID is not C/T with throttle closed: NOTE: At vehicle start, the TPREL will begin at about 1.25 volts, and count down to the lowest TP V value seen since engine start. If the TP V value goes below the "normal" range, then increases again, TPREL will set to the lower voltage. If TP V is about 0.04 volts greater than the TPREL value at closed throttle, the PCM will go into part throttle mode. Monitor TP V and TPREL PIDs for sudden changes while checking for intermittent TP circuit/connector concerns. Also check for loose/worn throttle plates. If no concern is found, GO to Z: Intermittent STEP Z1.
Intake Air System (air leaks)	GO to U: Intake Air Systems STEP HU1.
Additional Testing	GO to Z: Intermittent STEP Z1.