Mechanics

IDLE AIR CONTROL PROBLEMS WITH 96

1996 Dodge Caravan • 30,000 miles

I have a 96 dodge caravan 3.8 that stalls on me randomly, idles high, and sometimes wont stay running unless I hold the gas down for awhile. We did the code check and 25 came up for i.A.C. So we replaced that, but that didnt seem to help. What else can we try?
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Mandyk48
February 21, 2012.




If the code remains the same, you could have a fault with the wiring circuit or ECM.

Would you be carrying out test yourself?
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KHLow2008
Feb 21, 2012.
How do you test the ecm? Yes we'd be doing the testing ourselves

Tiny
Mandyk48
Feb 21, 2012.
You start by testing the wiring circuits.

TEST TC - 25A - IDLE AIR CONTROL MOTOR CIRCUITS

1. Ensure ignition is off for at least 10 seconds. Start engine and allow to idle for 20 seconds. Using scan tool, actuate idle air control motor to 1400 RPM.

2. Note if engine speed is within 1300-1500 RPM. If engine speed is not within specification, go to step 12). If engine speed is within specification, go to next step.

3. Using scan tool, actuate idle air control motor to 900 RPM. Note if engine speed is within 800-1000 RPM. If engine speed is not within specification, go to step 12). If engine speed is within specification, go to next step.

4. Conditions required to set DTC are not present at this time. The Powertrain Control Module (PCM) uses idle air control motor for controlling idle speed. Idle air control motor controls the amount of air by-passing the throttle blade. Go to next step.

5. DTC may be stored in PCM if PCM senses a short to ground or battery voltage on any of the 4 idle air control motor circuits while idle air control motor is operating. The PCM cannot detect an open circuit or stuck idle air control motor. Possible causes are: driver circuit shorted to ground or battery voltage, driver
circuits shorted together, defective PCM, shorted idle air control motor, defective connector terminals or wiring. Go to next step.

6. Check for defective wiring or connections at idle air control motor and PCM. Idle air control motor is mounted on the throttle body and contains a 4-pin connector. The PCM is located between driver's side front fender and power distribution center, near battery. If defective wiring or connections exist, repair as necessary. If no possible causes are found, go to next step.

7. Start engine and allow to idle. With engine at normal operating temperature, use scan tool to actuate IAC wiggle test. Engine speed should increase and decrease in accordance with display on scan tool.

8. If engine speed operates correctly, go to next step. If engine speed does not operate correctly, go to step 12).

9. Wiggle wiring harness from idle air control motor to the PCM. Note if idle air control motor stops operating while moving the wiring harness.

10. If idle air control motor does not stop operating, go to next step. If idle air control motor stops operating, repair wiring as necessary.

11. Stop wiggle test.

12. Ensure ignition is off. Disconnect connector at idle air control motor. Idle air control motor is mounted on throttle body and contains a 4-pin connector.

13. Check for miswired connector, defective wiring or connections at idle air motor. If miswired connector, defective wiring or connections exist, repair as necessary. If no defective wiring or connections exists, go to next step.

14. Using scan tool in ohmmeter mode, check resistance at terminal No. 3 (Brown/White) on connector for idle air control motor. If resistance less than 5 ohms, repair short to ground in Brown/White wire between PCM and idle air control motor. If resistance is 5 ohms or more, go to next step.

15. Using scan tool in ohmmeter mode, check resistance at terminal No. 2 (Yellow/Black) on connector for idle air control motor. If resistance less than 5 ohms, repair short to ground in Yellow/Black wire between PCM and idle air control motor. If resistance is 5 ohms or more, go to next step.

16. Using scan tool ohmmeter mode, check resistance at terminal 1 (Gray/Red) on connector for IAC motor connector. If resistance less than 5 ohms, repair short to ground in Gray/Red wire between PCM and idle air control motor. If resistance is 5 ohms or more, go to next step.

17. Using scan tool in ohmmeter mode, check resistance at terminal No. 4 (Violet/Black) on connector for idle air control motor. If resistance less than 5 ohms, repair short to ground in Violet/Black wire between PCM and idle air control motor. If resistance is 5 ohms or more, go to next step.

18. Using scan tool, actuate idle air control motor. Note that voltage may vary or remain constant during this test. Using scan tool in voltmeter mode, check voltage at terminal No. 3 (Brown/White wire) on connector for idle air control motor. If voltage is not more than 5 volts at any time, perform TEST TC-25B
.
If voltage was more than 5 volts at any time, go to next step.

19. Using scan tool in voltmeter mode, check voltage at terminal No. 2 (Yellow/Black) on connector for idle air control motor. If voltage not more than 5 volts at any time, perform TEST TC-25C. If voltage is more than 5 volts at any time, go to next step.

20. Using scan tool in voltmeter mode, check voltage at terminal No. 1 (Gray/Red) on connector for idle air control motor. If voltage not more than 5 volts at any time, perform TEST TC-25D. If voltage is more than 5 volts at any time, go to next step.

21. Using scan tool in voltmeter mode, check voltage at terminal No. 4 (Violet/Black) on connector for idle air control motor. If voltage is not more than 5 volts at any time, perform TEST TC-25E. If voltage is more than 5 volts at any time, go to next step.

22. Ensure ignition is off. Disconnect connectors from Powertrain Control Module (PCM). The PCM is located between driver's side front fender and power distribution center, near battery.

23. Inspect connector for miswired or damaged terminals. If connector miswired/damaged, repair as necessary. If connector is not miswired or terminals are not damaged, go to next step.

24. Using external ohmmeter, check resistance between terminal No. 3
(Brown/White wire) on connector for idle air control motor and each remaining terminal on the connector. This checks for a short between idle air control motor driver circuits.

25. If resistance is less than 5 ohms on any idle air control motor driver circuit, repair driver circuits that are shorted together. If
resistance is 5 ohms or more on all idle air control motor driver circuits, go to next step.

26. Using external ohmmeter, check resistance between terminal No. 2
(Yellow/Black wire) and terminals No. 1 (Gray/Red wire) and 4 (Violet/Black wire) on connector for idle air control motor. If resistance is less than 5 ohms on any idle air control motor driver circuit, repair driver circuits that are shorted together. If resistance is 5 ohms or more on idle air control motor driver circuits, go to next step.

27. Using external ohmmeter, check resistance between terminals No. 1 (Gray/Red wire) and 4 (Violet/Black wire) on connector for idle air control motor. If resistance is less than 5 ohms on idle air control motor driver circuit, repair the shorted together driver circuit. If resistance is 5 ohms or more on idle air control motor driver circuit, replace idle air control motor.

KHLow2008
Feb 21, 2012.

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