LEMON Manuals: Even more car manuals for everyone
Home >> GMC >> 1991 >> Value Van 7.4 N >> Repair and Diagnosis >> External Pages >> Different car >> Section 27 (Engine Controls - Tests W/Codes - 3.0L) >> Self-Diagnostic Tests >> Test TC-16A - Idle Air Control Motor Circuits (DTC 25)

Test TC-16A - Idle Air Control Motor Circuits (DTC 25)

WARNING: This page is about a different car, the 1995 Plymouth Voyager, 1995 Plymouth Grand Voyager, 1995 Dodge Grand Caravan, and 1995 Dodge Caravan. 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.
  1. Turn engine off. Turn ignition on. Start engine. Allow engine to idle for 20 seconds. Using scan tool, set engine speed to 1400 RPM. If engine speed is 1300-1500 RPM, go to next step. If engine speed is not 1300-1500 RPM, go to step 6).
  2. Using scan tool, set engine speed to 900 RPM. If engine speed is not 800-1000 RPM, go to step 6). If engine speed is 800-1000 RPM, go to next step.
  3. At this time, condition required to set DTC is not present. IDLE AIR CONTROL MOTOR CIRCUITS DTC sets if any of 4 wires are shorted to ground or to 12 volts for 2.75 seconds while IAC is active. Possible causes are: any one or more of 4 driver circuits shorted to ground, any one or more of 4 driver circuits shorted to power, any one or more of 4 driver circuits shorted together, failed PCM, or shorted IAC motor. PCM cannot detect an open driver circuit or a stuck IAC motor. Go to next step.
  4. Inspect wiring and connectors. Repair as required. Perform TEST VER-2. If wiring and connectors are okay, start engine. Using scan tool, actuate IAC wiggle test. Wiggle IAC motor wiring harness. Observe IAC motor operation.
  5. If IAC motor stops operating, repair harness or connectors as necessary. Perform TEST VER-2. If IAC motor does not stop operating, stop IAC wiggle test. See INACTIVE DTC CONDITION  . Test is complete. Perform TEST VER-2.
  6. Turn ignition off. Disconnect IAC motor connector. Inspect IAC motor connector for damaged or pushed-out terminals. Repair as necessary. Perform TEST VER-2. If wiring and connectors are okay, go to next step.
  7. Using scan tool ohmmeter mode, check resistance of IAC motor connector Brown/White wire. If resistance is less than 5 ohms, repair short to ground in Brown/White wire. Perform TEST VER-2. If resistance is more than 5 ohms, go to next step.
  8. Using scan tool, check resistance of IAC motor connector Yellow/Black wire. If resistance is less than 5 ohms, repair short to ground in Yellow/Black wire. Perform TEST VER-2. If resistance is more than 5 ohms, go to next step.
  9. Using scan tool, check resistance of IAC motor connector Gray/Red wire. If resistance is less than 5 ohms, repair short to ground in Gray/Red wire. Perform TEST VER-2. If resistance is more than 5 ohms, go to next step.
  10. Using scan tool, check resistance of IAC motor connector Violet/Black wire. If resistance is less than 5 ohms, repair short to ground in Violet/Black wire. Perform TEST VER-2. If resistance is more than 5 ohms, go to next step.
    NOTE: Voltage may switch or remain constant during steps 11)-14).
  11. Turn ignition on. Using scan tool, actuate IAC motor. Using scan tool in voltmeter mode, check voltage on IAC motor connector Brown/White wire. If voltage is more than 5 volts at any time, go to next step. If voltage is less than 5 volts, go to TEST TC-16B.
  12. Using scan tool, check voltage on IAC motor connector Yellow/Black wire. If voltage is more than 5 volts at any time, go to next step. If voltage is less than 5 volts, go to TEST TC-16C.
  13. Using scan tool, check voltage on IAC motor connector Gray/Red wire. If voltage is more than 5 volts at any time, go to next step. If voltage is less than 5 volts, go to TEST TC-16D.
  14. Using scan tool, check voltage on IAC motor connector Violet/Black wire. If voltage is more than 5 volts at any time, go to next step. If voltage is less than 5 volts, go to TEST TC-16E.
  15. Turn ignition off. Disconnect PCM connector. Inspect PCM connector for damaged or pushed-out terminals. Repair as necessary. Perform TEST VER-2. If connector is okay, go to next step.
  16. Using an external ohmmeter, check resistance between the following wires at IAC motor connector. Record resistance readings.
    • Brown/White Wire And Yellow/Black Wire
    • Brown/White Wire And Gray/Red Wire
    • Brown/White Wire And Violet/Black Wire
  17. If resistance between any 2 wires is less than 5 ohms, repair those wires for shorting together. Perform TEST VER-2. If resistance between all pairs of wires is more than 5 ohms, go to next step.
  18. Using an external ohmmeter, check resistance between the following wires at IAC motor connector. Record resistance readings.
    • Yellow/Black Wire And Gray/Red Wire
    • Yellow/Black Wire And Violet/Black Wire
  19. If resistance between any 2 wires is less than 5 ohms, repair those wires for shorting together. Perform TEST VER-2. If resistance between all pairs of wires is more than 5 ohms, go to next step.
  20. Using an external ohmmeter, check resistance between Gray/Red wire and Violet/Black wire at IAC motor connector.
  21. If resistance between wires is less than 5 ohms, repair wires for shorting together. Perform TEST VER-2. If resistance between wires is more than 5 ohms, replace IAC motor. Perform TEST VER-2.
scientia non olet · About LEMON Manuals