Test TC-28A - Idle Air Control Motor Circuits (DTC 25)

WARNING: This page is about a different car, the 1994 Eagle Vision, 1994 Dodge Intrepid, and 1994 Chrysler Concorde. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: For circuit & connector terminal identification, see CONNECTOR IDENTIFICATION DIRECTORY . For wiring diagrams, see WIRING DIAGRAMS section. After each repair, perform TEST VER-2 .

Using DRB, erase trouble codes. Using DRB, actuate Idle Air Control (IAC) motor. If IAC motor trouble code returns, go to step 4). If IAC motor trouble code does not return, go to next step.
At this time, the condition required to set trouble code is not present. IDLE AIR CONTROL MOTOR CIRCUITS trouble code sets if any of the 4 IAC motor connector wires are shorted to ground or to 12 volts. Open wires will not set this trouble code. Possible causes are: harness shorted to ground, harness shorted to 12 volts, or IAC motor shorted internally.
Inspect wiring and connectors. Repair as required. If wiring and connectors are okay, see INACTIVE TROUBLE CODE CONDITION in this article. Test is complete.
If IAC motor trouble code returns in step 1), turn ignition off. Disconnect and inspect IAC motor connector. If any terminal is damaged, pushed out or miswired, repair IAC motor connector as necessary. If IAC motor connector is okay, go to next step.
Turn ignition on. Using DRB, erase trouble codes. Using DRB, actuate IAC motor. If IAC motor trouble code does not return, replace IAC motor. If IAC motor trouble code returns, go to next step.
NOTE: Voltage may switch or remain constant during steps 6)-9).
Using DRB in voltmeter mode, check voltage on IAC motor connector terminal No. 1 wire (Gray/Red wire). If voltage is not more than 10 volts at any time, go to TEST TC-28B . If voltage is more than 10 volts at any time, go to next step.
Check voltage on IAC motor connector terminal No. 2 (Yellow/Black wire). If voltage is not more than 10 volts at any time, go to TEST TC-28C . If voltage is more than 10 volts at any time, go to next step.
Check voltage on IAC motor connector terminal No. 3 (Brown/White wire). If voltage is not more than 10 volts at any time, go to TEST TC-28D . If voltage is more than 10 volts at any time, go to next step.
Check voltage on IAC motor connector terminal No. 4 (Violet/Black wire). If voltage is not more than 10 volts at any time, go to TEST TC-28E . If voltage is more than 10 volts at any time, go to next step.
Turn ignition off. Disconnect and inspect Powertrain Control Module (PCM) connector. PCM is located under air cleaner. If any terminal is damaged, pushed out or miswired, repair as necessary. If PCM connector is okay, go to next step.
Using an external ohmmeter, check resistance between IAC motor connector terminal No. 1 (Gray/Red wire) and (in turn) terminals No. 2 (Yellow/Black wire), No. 3 (Brown/White wire) and No. 4 (Violet/Black wire). If resistance is less than 5 ohms between any circuit(s), repair circuit(s) shorted together. If resistance is more than 5 ohms on all circuits, go to next step.
Using an external ohmmeter, check resistance between IAC motor connector terminal No. 2 (Yellow/Black wire) and (in turn) terminals No. 3 (Brown/White wire) and No. 4 (Violet/Black wire). If resistance is less than 5 ohms between any circuit(s), repair circuit(s) shorted together. If resistance is more than 5 ohms on all circuits, go to next step.
Using an external ohmmeter, check resistance between IAC motor connector terminals No. 3 (Brown/White wire) and No. 4 (Violet/Black wire). If resistance is less than 5 ohms, repair circuit shorted together. If resistance is more than 5 ohms, replace PCM.