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Home >> GMC >> 1991 >> Value Van 7.4 N >> Repair and Diagnosis >> External Pages >> Different car >> Section 43 (Engine Controls - Tests W/Codes - 8.0L) >> Self-Diagnostic Tests >> Test NTC-9A - Checking Idle Air Control Motor

Test NTC-9A - Checking Idle Air Control Motor

WARNING: This page is about a different car, the 1995 Dodge Pickup and 1995 Dodge Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: For circuit and connector terminal identification, see CONNECTOR IDENTIFICATION  . For wiring diagrams, see WIRING DIAGRAMS  section at the end of this article.
  1. Using scan tool, set engine speed to 1100 RPM. If engine speed set at 1050-1150 RPM, idle speed motor is operating properly. Test is complete. If engine speed did not set at 1050-1150 RPM, return engine to normal idle speed. Disconnect Idle Air Control (IAC) motor connector.
  2. Using scan tool in voltmeter mode, check voltage on IAC motor connector, driver No. 1 circuit (Brown/White wire) while momentarily opening and closing throttle. If voltage stayed less than one volt, go to TEST NTC-9B. If voltage did not stay less than one volt, go to next step.
  3. Using scan tool, check voltage on IAC motor connector, driver No. 2 circuit (Yellow/Black wire) while momentarily opening and closing throttle. If voltage stayed less than one volt, go to TEST NTC-9B. If voltage did not stay less than one volt, go to next step.
  4. Using scan tool, check voltage on IAC motor connector, driver No. 3 circuit (Gray/Red wire) while momentarily opening and closing throttle. If voltage stayed less than one volt, go to TEST NTC-9B. If voltage did not stay less than one volt, go to next step.
  5. Using scan tool, check voltage on IAC motor connector, driver No. 4 circuit (Violet/Black wire) while momentarily opening and closing throttle. If voltage stayed less than one volt, go to TEST NTC-9B. If voltage did not stay less than one volt, go to next step.
  6. Check engine for vacuum leaks. Repair as required. Perform TEST VER-2. If no vacuum leaks are observed, replace IAC motor. Perform TEST VER-2.