4 Ways to Control the Idle Control Valve

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4 Ways to Control the Idle Control Valve
4 Ways to Control the Idle Control Valve
Anonim

The idle air control valve - or idle control valve - adjusts the engine's idling speed. This is controlled by the engine computer. Sometimes some parts malfunction resulting in the car idling strangely or stalling. This article will show you how to check the idle valve.

Steps

Method 1 of 4: General Motors

Check an Idle Air Control Valve Step 1
Check an Idle Air Control Valve Step 1

Step 1. Check if the "Check Engine" light is on

If yes, use an OBD II scanner to retrieve the codes if the car is from 1996 or later.

If the codes are between P505 and P509, you have a problem with the idle system which could be due to the control valve (IAC)

Check an Idle Air Control Valve Step 2
Check an Idle Air Control Valve Step 2

Step 2. Older cars may have a code that can only be recovered with an original OBD scanner

Code 11 indicates the same problem as new machines and the diagnosis procedure is the same.

Check an Idle Air Control Valve Step 3
Check an Idle Air Control Valve Step 3

Step 3. Disconnect the IAC valve and turn on the machine

At this point the idle speed should increase as expected.

Check an Idle Air Control Valve Step 4
Check an Idle Air Control Valve Step 4

Step 4. Turn off the machine and reconnect the IAC valve

Restart the engine and the idle speed should return to normal. If it does, this MAY rule out the IAC but further testing will be needed. If the cost of a new valve is prohibitive, try finding one in a scrap yard and see if there is any difference.

Check an Idle Air Control Valve Step 5
Check an Idle Air Control Valve Step 5

Step 5. Use a phase finder if the idle speed does not work as expected

Connect it to the air control solenoid and look at the instrument.

The detector will flash or become dimmer for the four circuits if the problem is with the valve. Otherwise it means that the problem is related to the PCM (powertrain control module)

Method 2 of 4: Ford

Check an Idle Air Control Valve Step 6
Check an Idle Air Control Valve Step 6

Step 1. See if the "Check Engine" light is on

If so, use an OBD II scanner to retrieve the codes if the car is from 1996 or later. As with General Motors, if the codes are P505 to P509, you have a problem with the idle system.

If your car is older than '96, you will need a regular OBD scanner. You may get codes 12, 13, 16, 17, or 19, which indicate that the minimum is wrong. Sometimes codes 47 or 48 appear, indicating an air leak

Check an Idle Air Control Valve Step 7
Check an Idle Air Control Valve Step 7

Step 2. Turn off the machine and disconnect the IAC solenoid if you get any of the above codes

Check an Idle Air Control Valve Step 8
Check an Idle Air Control Valve Step 8

Step 3. Restart the engine and check if the RPM has decreased

If there are no changes, the problem is with the solenoid.

Check an Idle Air Control Valve Step 9
Check an Idle Air Control Valve Step 9

Step 4. Use an ohm reader to check the solenoid by hooking the positive lead to the VPWR and the negative to the IAC

The resistance value should be between 7.0 ohms and 13.0 ohms. If you are out of these values then the IAC solenoid is malfunctioning

Method 3 of 4: Chrysler

Check an Idle Air Control Valve Step 10
Check an Idle Air Control Valve Step 10

Step 1. Use a scanner (OBD for older 1996 vehicles or OBD II for newer vehicles) to retrieve the codes if the Check Engine Light is on

Code 25 in older cars or P505 to P509 for newer models indicates a problem with the idle system

Check an Idle Air Control Valve Step 11
Check an Idle Air Control Valve Step 11

Step 2. Use a bidirectional scanner to check idle speed by sending commands

If the motor does not respond to commands then there is a problem with the IAC solenoid, wiring or driving circuit.

Method 4 of 4: Other brands

Check an Idle Air Control Valve Step 12
Check an Idle Air Control Valve Step 12

Step 1. Check your car's manual for specific instructions

The process should be similar to those described above, but there may be additional steps or a combination of methods.

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