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Test FC-22A - Idle Air Control Motor Circuits (DTC 25)

NOTE: For connector terminal identification, see CONNECTOR IDENTIFICATION . For appropriate wiring diagram, see WIRING DIAGRAMS  at end of article.
  1. Using DRB-II, erase fault codes. Turn ignition off. Start engine and wait 30 seconds. If Idle Air Control (IAC) motor fault returns, go tostep 4). If idle air control motor fault does not return, go to next step.
  2. At this time, the condition required to set fault is not present. IDLE AIR CONTROL MOTOR CIRCUITS fault sets if any of the 4 wires are shorted to ground or to 12 volts. Open wires will not set this fault. Possible causes are: harness shorted to ground, harness shorted to 12 volts, or IAC motor is shorted internally.
  3. Inspect wiring and connectors. Repair as required. Perform TEST VER-2. If wiring and connectors are okay, see INACTIVE FAULT CONDITION . Perform TEST VER-2.
  4. If IAC motor fault returned in step 1), turn ignition off. Disconnect IAC motor connector. Turn ignition on. Using DRB-II, actuate IAC motor.
  5. Place DRB-II in voltmeter mode. Using DRB-II, check voltage of IAC motor connector driver No. 3 wire (Gray/Red wire). If circuit is okay, voltage will switch from less than one volt to more than 10 volts.
  6. If voltage is less than one volt, repair IAC motor connector driverNo. 3 wire for a short to ground. Perform TEST VER-2. If voltage is more than 10 volts, repair IAC driver No. 3 wire for a short to voltage. Perform TEST VER-2.
  7. If voltage is less than 10 volts, use DRB-II to check voltage of IAC motor connector driver No. 2 wire (Yellow/Black wire). If voltage is less than one volt, repair IAC motor connector driver No. 2 wire for a short to ground. Perform TEST VER-2. If voltage is more than 10 volts, repair IAC driver No. 2 wire for a short to voltage. Perform TEST VER-2.
  8. If voltage is less than 10 volts, use DRB-II to check voltage of IAC motor connector driver No. 1 wire (Brown/White wire). If voltage is less than one volt, repair IAC motor connector driver No. 1 wire for a short to ground. Perform TEST VER-2. If voltage is more than 10 volts, repair driver No. 1 wire for a short to voltage. Perform TEST VER-2.
  9. If voltage is less than 10 volts, use DRB-II to check voltage of IAC motor connector driver No. 4 wire (Violet/Black wire). If voltage is less than one volt, repair IAC motor connector driver No. 4 wire for a short to ground. Perform TEST VER-2. If voltage is more than 10 volts, repair IAC driver No. 4 wire for a short to voltage. Perform TEST VER-2.
  10. If voltage is less than 10 volts, turn ignition off. Connect IAC motor connector. Disconnect Powertrain Control Module (PCM). Using an external ohmmeter, check resistance between PCM connector terminal No. 39, IAC motor driver No. 3 wire (Gray/Red wire) and PCM connector terminal No. 59, IAC motor driver No. 4 wire (Violet/Black wire).
  11. If resistance is less than 35 ohms, replace IAC motor. Perform TEST VER-2. If resistance is more than 35 ohms, check resistance between PCM connector terminal No. 40, IAC motor driver No. 1 (Brown/White wire) and PCM connector terminal No. 60, IAC motor driver No. 2 wire (Yellow/Black wire).
  12. If resistance is less than 35 ohms, replace IAC motor. Perform TEST VER-2. If resistance is more than 35 ohms, check resistance between PCM connector terminal No. 39, IAC motor driver No. 3 wire (Gray/Red wire) and PCM connector terminal No. 60, IAC motor driver No. 2 wire (Yellow/Black wire).
  13. If resistance is less than 10 ohms, repair IAC motor driver No. 3 wire for a short to IAC motor driver No. 2 wire. Perform TEST VER-2. If resistance is more than 10 ohms but less than 75 ohms, go to next step. If resistance is more than 10 ohms but less than 120 ohms, repair IAC motor driver No. 1 wire for a short to IAC driver No. 4 wire. Perform TEST VER-2. If resistance is more than 120 ohms, replace PCM. Perform TEST VER-2.
  14. If resistance was more than 10 ohms but less than 75 ohms instep 13), check resistance between PCM connector terminal No. 59, IAC motor driver No. 4 wire (Violet/Black wire) and PCM connector terminal No. 60, IAC motor driver No. 2 wire (Yellow/Black wire).
  15. If resistance is less than 10 ohms, repair IAC motor driver No. 2 wire for a short to IAC driver No. 4 wire. Perform TEST VER-2. If resistance is more than 10 ohms, repair IAC motor driver No. 1 wire for a short to IAC motor driver No. 4 wire. Perform TEST VER-2.
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