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. Testing and Inspection

ELECTRICAL CHECK

Idle Air Control Valve Connection:

- Disconnect harness connector from IAC valve.

Idle Air Control Valve Testing:

- Measure resistance on IAC valve.
^ Specified value: 7-11 ohms

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

NOTE: At room temperature, the resistance lies lower in the tolerance range; with the engine warmed to operating temperature, it is higher in the tolerance range.

MECHANICAL CHECK
- Remove idle air control valve.

Idle Air Control Valve:

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

CAUTION!
When checking free movement, do not move the rotary slide valve with a screwdriver or other tool.

- Re-connect harness connector to removed valve.
- Switch ignition on.
- Use On-Board Diagnostics, Output Diagnostic Test Mode (DTM) to activate idle air control valve. Testing and Inspection
- 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.

Idle Air Control Valve Terminal Identification:

- Push back boot from harness connector (stays connected).
- Use On-Board Diagnostics, Output Diagnostic Test Mode (DTM) to activate idle air control valve. Testing and Inspection
- Connect US 1115 LED tester or equivalent between harness connector terminal 1 and Ground (GND).
^ LED must blink
- Connect LED tester between harness connector terminal 2 and battery positive (B+).
^ LED must light up

If specified results are not obtained:
- Check for open circuit or short circuit between IAC valve harness connector and ECM harness connector.
- Eliminate wiring break or short circuit 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 mechanically seized valve.