Intake Manifold Tuning (IMT) Valve, Checking

NOTE:
- Without current the tuning -N156- is closed.
- Component locations. Locations


Checking flow and for leaks
- Remove intake manifold tuning valve -N156-.
- After removing, re-connect valve -N156- to harness connector.
- Conduct output Diagnostic Test Mode (DTM) for intake manifold tuning valve -N156-. Refer to "Output Diagnostic Test Mode (DTM) (Function 03)"
- Blow through hose to valve output DTM and make sure that -N156- opens and closes correctly.

If -N156- does not open and close:
- Replace intake manifold tuning valve -N156-.

Electrical check of intake manifold tuning valve -N156-
- Disconnect harness connector from intake manifold tuning valve.







- Connect multimeter for resistance measurement between contacts.
- Specified value: 25 - 35 Ohms.

If the specified value is not attained:
- Replace intake manifold tuning valve.







Checking voltage supply for intake manifold tuning valve -N156-

Test requirements
- Fuse for intake manifold tuning valve OK
- Disconnect harness connector from intake manifold tuning valve.
- Connect LED test lamp VAG 1527 with wires from test kit VAG 1594 between terminal 1 (B+) of 2-pin connector and engine Ground.
- Crank starter.
- LED must light up.

If LED does not light up:
- Check fuse for -N156-
- Check wiring from terminal 1 of 2-pin connector to fuse per wiring diagram for continuity.
- Specified value: max. 1 Ohm

If wiring is OK:
- Check fuel pump relay and signal to relay.

Checking signal for intake manifold tuning valve -N156-

- Connect LED test lamp VAG 1527 with wires from test kit VAG 1594 between terminals of 2-pin connector for -N156-.
- Conduct output Diagnostic Test Mode (DTM) for intake manifold tuning valve -N156-. Refer to "Output Diagnostic Test Mode (DTM) (Function 03)"
- When the intake manifold tuning valve is activated the LED must flash.

If LED does not flash or stays on continuously:
- Connect VAG 1598/22 test box to ECM harness connector.

If LED does not flash:
- Check wiring from terminal 2 of 2-pin connector to terminal 64 of test box for continuity and short circuit to B+ per wiring diagram.

If LED stays on continuously:







- Check wiring from terminal 2 of 2-pin connector to terminal 64 of test box for ground per wiring diagram.

If wiring is OK:
- Replace Motronic ECM -J220-.
- Carry out adaptation of throttle valve control module to ECM.
- Check readiness code. If Diagnostic Trouble Code (DTC) memory has been erased, or ECM was disconnected, generate new readiness code.