Idle Air Control (IAC) Valve, Electrical Testing

Idle Air Control (IAC) Valve, Electrical Testing

- Check IAC valve -N71- mechanical function.
- Disconnect harness connector from valve.







- Connect multimeter US 1119 (Fluke 83 or equivalent) and check resistance across terminals on IAC valve.
Specified value: 7.0 - 11.0 ohms


NOTE: At room temperature the resistance is in the lower part of the specified range. At operating temperature the resistance is in the upper part of the range.


If resistance is outside specified range:
- Replace IAC valve -N71-.
- Check readiness code. If DTC memory has been erased, generate new readiness code.
Refer "Monitors, Trips and/or Drive Cycle/Checking, Readiness Code", Testing and Inspection .
Refer "Monitors, Trips and/or Drive Cycle/Generating, Readiness Code" Testing and Inspection

Checking idle air control signal from ECM







- Disconnect wiring harness connector from IAC valve -N71- and connect VAG1527B LED voltage tester across connector terminals 1 and 2.
- Initiate output Diagnostic Test Mode (DTM) and check IAC valve. Refer "Scan Tool Testing", "Output Diagnostic Test Mode (DTM), (Function 03)", Testing and Inspection
LED must flash.


NOTE:
- The LED does not go completely out, but becomes brighter and dimmer.
- The output Diagnostic Test Mode (DTM) signal for the IAC valve is interrupted after one minute. To repeat the test, briefly switch the ignition off and start the output DTM again.


If LED does not flash:
- Connect VAG1598/19 test box to ECM harness connector. Refer "Scan Tool Testing/Scan Tool Connecting and Initial Checks/VAG1598/19 Test Box, Connecting" Testing and Inspection







- Check wiring for open circuit or short circuit between IAC valve and ECM/test box.

IAC valve connector VAG1598/19 test box socket (ECM terminal)
terminal
1 D5
2 D1

If wiring is OK and there is no signal:
- Replace ECM and generate readiness code. Refer "Monitors, Trips and/or Drive Cycle (Readiness Code)/Generating, Readiness Code" Testing and Inspection