TP. MFI #33 No Idle Air Control (IAC) Valve Signal

TP. MFI#33

MFI#33 No idle air control (IAC) valve signal




Fault message conditions:
The fault message is logged if voltage is below 2.5 V for 300 ms.

Causes of fault:
Break or grounding between MFI#33 and the valve.
Break or grounding in the IAC valve.

Fault symptoms:
Low idle speed.

TP1




Volvo ST, Test box
- Disconnect the ST in accordance with QA2. QA. Connecting The Volvo Scan Tool (ST)
- Connect the test box to MFI and check the GND points in accordance with P1-P2. P. Test Box, Signal Description
^ Continue with Checking the wiring and valve resistance TP2.

TP2




Checking the wiring and valve resistance
- Ignition off.
Connect an ohmmeter between MFI#33 and MFI#9.
The ohmmeter should read approx. 8 ohms.

If this value is OK
^ check the wiring's resistance to GND TP3.

If the reading is incorrect
^ check the valve resistance TP8.

TP3




Checking the wiring's resistance to GND
- Ignition off.
- Disconnect the IAC valve.
Connect an ohmmeter between MFI#33 and MFI#5 (GND).
The ohmmeter should read infinite resistance.

If this value is OK
^ check the signal to valve TP4.

If the reading deviates
^ check the wiring between the control modules for grounding In accordance with NA3. NA. Checking the Wiring

TP4




Checking the power supply
- Connect the control module to the test box.
- Connect the IAC valve
- Install the fuse.
- Ignition on.
Connect a voltmeter between MFI#33 and MFI#5 (GND).
The voltmeter should read battery voltage.

If this value is OK
^ check the control of #38 TP5.

If the reading deviates
^ check the wiring between MFI#33 and the valve and between MFI#9 and the valve for breaks in accordance with NA2. NA. Checking the Wiring

TP5




Checking control #33
- Start the engine and let it idle.
The voltmeter should read 7-10 V.

If this value is OK
Intermittent fault.
^ Check the connections for loose contacts in accordance with NA5. NA. Checking the Wiring

If the voltage does not drop
^ try using a new control module.

TP6




Checking the valve resistance
- Ignition off.
- Disconnect the IAC valve.
Connect an ohmmeter between terminals 1 and 2 on the valve.
The ohmmeter should read approx. 8 ohms.

If this value is OK:
^ Check the wiring between MFI#33 and the valve and the wiring between MFI#9 and the valve for breaks in accordance with NA2. NA. Checking the Wiring

If the reading is incorrect:
^ Try using a new IAC valve.