Diagnostic Procedures
- Start and warm engine to normal operating temperature. Ensure ECT is greater than 140°F (60°C). Using scan tool, command different RPMs up and down in the 650-875 RPM range. If engine speed is consistently 200 RPM or more less than desired idle speed, go to next step. If engine speed is not consistently 200 RPM or more less than desired idle speed, problem is intermittent. See DIAGNOSTIC AIDS .
- Check for stuck IAC valve, vacuum leak, binding throttle linkage or low/high generator output. Ensure TP sensor angle reads zero percent when throttle is closed. Repair as necessary.