Intake Manifold Tuning Valve, Checking

Intake Manifold Tuning Valve, Checking

Special tools, testers and auxiliary items required

• Multimeter.

• Wiring diagram.

Test requirements

• Fuse (SB7) OK.

• The Motronic Engine Control Module (ECM) Power Supply Relay (J271) OK.

• The parking brake engaged.

• The battery voltage at least 12.5 V.

• The selector lever of automatic transmission in position "P" or "N".

• All electrical consumers switched off (radiator fan must NOT run during test).

• A/C switched off.

• The fuel tank at least 1/4 filled.

• The ignition switched off.

Test procedure

- Perform a preliminary check to verify the customers complaint. Diagnostic Mode 09 - Read Vehicle Information.

Start diagnosis

- Disconnect the Intake Manifold Runner Control (IMRC) Valve (N316) electrical harness connector - arrow -.





Checking internal resistance

- Using a Multimeter, check the Intake Manifold Tuning (IMT) Valve (N156) terminals 1 to 2 for resistance.





Specified value: 450 to 1000 ohms.

If the specified value was not obtained:

- Replace the Intake Manifold Tuning (IMT) Valve (N156).

If the specified value was obtained:

Checking voltage

Crank the engine.

- Using a Multimeter, check the Intake Manifold Tuning (IMT) Valve (N156) electrical harness connector terminal 1 to ground (GND) for voltage.





Specified value: battery voltage.

- Switch the ignition off.

If the specified value was not obtained:

- Check the wiring from the Intake Manifold Tuning (IMT) Valve (N156) electrical harness connector terminal 1 to the Motronic Engine Control Module (ECM) Power Supply Relay (J271) socket 2/87 for a short circuit to Ground (GND), or an open circuit.

- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

- If necessary, repair the wiring connection.

If no malfunctions are found in the wiring:

Checking wiring

If the manufacturers test box is being used. Perform the following step.

- Install the test box.

If the manufacturers test box is not being used. Perform the following step.

- Remove the Motronic Engine Control Module (ECM) (J623). Refer to => [ Engine Control Module, Replacing ] Engine Control Module, Replacing.

- Using a multimeter, check the Intake Manifold Tuning (IMT) Valve (N156) electrical harness connector terminal 2 to the Engine Control Module (ECM) (J623) electrical harness connector T40 terminal 121 for resistance.






Specified value: 1.5 ohms Max.

If the specification was not obtained:

- Check the wiring for a short circuit to each other, Battery (+), and Ground (GND).

- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

- If necessary, repair the faulty wiring connection.

If no malfunction is detected in the wiring:

- Erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Mode 04 - Erase DTC Memory.

- Perform a road test to verify repair.

If the DTC does not return:

Repair complete, Generate readiness code. Refer to => [ Readiness Code Description ] Diagnostic Mode 09 - Read Vehicle Information.

- End diagnosis.

If the DTC does return and no malfunction is detected in the wiring and the voltage supply was OK:

- Replace the Engine Control Module (ECM) (J623). Refer to => [ Engine Control Module, Replacing ] Engine Control Module, Replacing.

- Assembly is performed in the reverse of the removal.

Final procedures

After the repair work, the following work steps must be performed in the following sequence:

1. Check the DTC memory. Refer to => [ Diagnostic Mode 03 - Read DTC Memory ] Diagnostic Mode 03 - Read DTC Memory.

2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Mode 04 - Erase DTC Memory.

3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code ] Engine.

End of diagnosis