Idle Speed/Throttle Actuator - Electronic: Testing and Inspection

NOTE: For function testing of the Idle Air Control (IAC) valve, also see, On-Board Diagnostics "Read Measuring Value Block" function 08, display groups 004 through 018, Testing and Inspection.

ELECTRICAL CHECK

Idle Air Control Valve Connection:

- Disconnect harness connector from IAC valve -N71-.

Idle Air Control Valve Testing:

- Measure IAC valve resistance by connecting multimeter (Fluke 83 or equivalent) between connector terminals using jumper wires from connector test kit VW 1594.

Specified Value: 7-11 ohms

If specified values are not obtained:
- Replace IAC valve.

NOTE: At room temperature, the resistance value will be lower. The resistance value will be higher if the Idle Air Control (IAC) valve is measured at under-hood operating temperatures.

MECHANICAL CHECK
- Remove Idle Air Control valve.

Idle Air Control Valve:

- Check rotary slide valve (arrow) for signs of scoring (by visual inspection).

CAUTION: Do not check for ease of movement by prying on the rotary slide using a screwdriver or other tools that could potentially cause scratching.

- Re-connect harness connector to removed valve.
- Switch ignition on.
- Use scan tool "Output Diagnostic Test Mode" function 03 to trigger Idle Air Control (IAC) valve -N71-.
- Check whether rotary slide valve runs properly from stop to stop.

If there are signs of scoring that impair free movement, or if the rotary slide does not move freely (sticks, runs slowly or does not run up to both stops):
- Replace idle air control valve

If there is no valve activation during output DTM:
- Check IAC valve activation.

CHECKING IDLE AIR CONTROL VALVE ACTIVATION
^ Electrical check OK.

- Push back boot from harness connector (stays connected).
- Use scan tool "Output Diagnostic Test Mode" function 03 to trigger Idle Air Control (IAC) valve -N71-.

Idle Air Control Valve Terminal Identification:

- Connect VAG 1 527B voltage tester between connector terminal 1 and engine Ground (GND).

Specified Result: voltage tester must flash.

- Connect voltage tester between connector terminal 2 and battery positive voltage (8+).

Specified Result: voltage tester must light up.

If specified results are not obtained:
- Connect VAG 1598/19 test box to ECM harness connector (ECM is left disconnected).
- Check wiring between harness connector terminal 1 (in engine compartment) to test box socket D11, then check wiring between harness connector terminal 2 and test box socket D9 using wiring diagram; correct as necessary.

If wiring is OK and activation fails:
- Replace ECM.

If activation and wiring is OK and there is still no valve reaction:
- Replace Idle Air Control (IAC) valve.