Idle Control System Troubleshooting Guide

Idle Control System:

READING THE CHART
Across each row in the chart, the sub systems that could be sources of a symptom are ranked in the order they should be inspected, starting with (1). Find the symptom in the left column, read across to the most likely source, then refer to the component or system listed at the top of that column. If inspection shows that system is OK, try the next system (2), etc.

NOTE: If the idle speed is out of specification and the MALFUNCTION INDICATOR WARNING LAMP does not blink CODE [14], check the following items:

a. Adjust idle speed
b. A/C signal
c. A/T shift position signal
d. Brake switch signal
e. Starter switch signal
f. P/S oil pressure signal
g. Fast idle valve
h. Air boost valve
i. Hoses and connections
j. IAC valve and its mounting O-rings

If the above items are normal, substitute a known good IAC Valve and readjust the idle speed. If the idle speed still cannot be adjusted to specification (and MALFUNCTION INDICATOR WARNING LAMP does not blink CODE [14] after IAC Valve replacement, substitute a known good ECM and recheck. If symptom goes away, replace the original ECM.