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Home >> Jeep >> 1996 >> Grand Cherokee Limited, 5.2 Y >> Repair and Diagnosis >> External Pages >> Different car >> Section 180 (Engine Controls - Tests W/Codes - 4.0L) >> Self-Diagnostic Tests >> Test NTC-9A - Checking Idle Air Control (IAC) Motor

Test NTC-9A - Checking Idle Air Control (IAC) Motor

WARNING: This page is about a different car, the 1995 Jeep Wrangler, 1995 Jeep Grand Cherokee, and 1995 Jeep Cherokee. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Perform TEST NTC-1A  before proceeding with this test. For connector terminal identification, see CONNECTOR IDENTIFICATION  at beginning of article. For wiring diagrams, see WIRING DIAGRAMS  at the end of this article. Perform TEST VER-2A  after each repair.
  1. Using scan tool, set engine speed to 1100 RPM. If engine speed set at 1050-1150 RPM, IAC motor is operating properly. Test is complete. If engine speed did not set at 1050-1150 RPM, return engine to normal idle speed. Disconnect IAC motor 4-pin connector and ensure connector is clean and not damaged.
  2. Using scan tool in voltmeter mode, check voltage on IAC No. 1 driver circuit (Gray/Red wire) at 4-pin connector terminal No. 1 on XJ and YJ bodies or No. 4 on ZJ. Momentarily open and close throttle. If voltage stays less than one volt, go to TEST NTC-9B  . If voltage increases to more than one volt, go to next step.
  3. Repeat step 2) for each IAC motor driver. If voltage stays less than one volt for any driver circuit, go to TEST NTC-9B  . If voltage increases to more than one volt for all driver circuits, go to step 4). Check voltage on:
    • IAC No. 2 driver circuit (Yellow/Black wire on XJ and YJ bodies or Brown/White wire on ZJ body) at 4-pin connector terminal No. 2 on XJ and YJ bodies or No. 3 on ZJ body.
    • IAC No. 3 driver circuit (Brown/White wire on XJ and YJ bodies or Violet/Black wire on ZJ body) at 4-pin connector terminal No. 3 on XJ and YJ bodies or No. 2 on ZJ body.
    • IAC No. 4 driver circuit (Violet/Black wire on XJ and YJ bodies or Yellow/Black wire on ZJ body) at 4-pin connector terminal No. 4 on XJ and YJ bodies or No. 1 on ZJ body.
  4. Check engine for vacuum leaks. Repair as necessary. If no vacuum leaks are observed, remove IAC motor from throttle body. Reconnect IAC motor 4-pin connector. Using scan tool, actuate IAC motor. If IAC motor pintle does not extend or retract, replace idle air control motor. If IAC motor pintle extends and retracts, IAC motor is operating normally at this time. Test is complete.
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