Checking function

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Switch ignition on.
MIL must light up

If the MIL does not light up with ignition switched on:

MIL IS NOT ACTIVATED OR DOES NOT LIGHT UP BECAUSE OF AN OPEN CIRCUIT

Cause:	Corrective action:
MIL is not activated or does not light up because of an open circuit.	Switch ignition off. Connect VAG1598/31 test box. See WIRING AND COMPONENT CHECK WITH VAG1598/31 TEST BOX . Bridge sockets 2 and 47 on test box Switch ignition on. MIL must light up. If the MIL does not light up: Switch ignition off. Check whether lamp is burned out and test voltage supply to lamp wiring diagram. If the lamp and the voltage supply are OK: Check for open circuit or short circuit in wiring between engine control module and MIL using wiring diagram. Determine and eliminate malfunction.
	If there are no malfunctions in the wiring to the MIL:
Malfunction cause:	Engine control module (ECM) faulty. Replace Engine Control Module (ECM). See MOTRONIC ENGINE CONTROL MODULE (ECM) -J220- (WITHOUT METAL ANTI -THEFT HOUSING), REPLACING .

Cause:

Corrective action:

MIL is not activated or does not light up because of an open circuit.

Switch ignition off.
Connect VAG1598/31 test box. See WIRING AND COMPONENT CHECK WITH VAG1598/31 TEST BOX .
Bridge sockets 2 and 47 on test box
Switch ignition on.

MIL must light up.
If the MIL does not light up:

Switch ignition off.
Check whether lamp is burned out and test voltage supply to lamp wiring diagram.

If the lamp and the voltage supply are OK:

Check for open circuit or short circuit in wiring between engine control module and MIL using wiring diagram. Determine and eliminate malfunction.

If there are no malfunctions in the wiring to the MIL:

Malfunction cause:

Engine control module (ECM) faulty. Replace Engine Control Module (ECM). See MOTRONIC ENGINE CONTROL MODULE (ECM) -J220- (WITHOUT METAL ANTI -THEFT HOUSING), REPLACING .

If MIL remains lit for more than 3 seconds (i.e. continuously) when ignition is on, proceed with test as follows:

Start engine and allow it to run at idling speed.
MIL should go out.

If the MIL does not go out:

Check DTC memory of Engine Control Module (ECM). See DIAGNOSTIC TROUBLE CODE (DTC) MEMORY, CHECKING AND ERASING .

If no DTCs are stored:

MIL IS ACTIVATED VIA SHORT CIRCUIT TO GROUND

Cause:	Corrective action:
MIL is activated via short circuit to Ground (GND).	Switch ignition off. Connect VAG1598/31 test box. See WIRING AND COMPONENT CHECK WITH VAG1598/31 TEST BOX Measure resistance between vehicle Ground and socket 47 on test box. Specification: infinity (because wire should not have any direct Ground connection). If the specification is not reached: Determine and eliminate short circuit to Ground in wiring between engine control module and MIL using wiring diagram.
	If there are no malfunctions in the wiring to the MIL:
Malfunction cause:	Engine control module (ECM) faulty. Replace Engine Control Module (ECM). See MOTRONIC ENGINE CONTROL MODULE (ECM) -J220- (WITHOUT METAL ANTI -THEFT HOUSING), REPLACING .

Cause:

Corrective action:

MIL is activated via short circuit to Ground (GND).

Switch ignition off.
Connect VAG1598/31 test box. See WIRING AND COMPONENT CHECK WITH VAG1598/31 TEST BOX
Measure resistance between vehicle Ground and socket 47 on test box. Specification: infinity (because wire should not have any direct Ground connection).

If the specification is not reached:

Determine and eliminate short circuit to Ground in wiring between engine control module and MIL using wiring diagram.

If there are no malfunctions in the wiring to the MIL:

Malfunction cause:

Engine control module (ECM) faulty. Replace Engine Control Module (ECM). See MOTRONIC ENGINE CONTROL MODULE (ECM) -J220- (WITHOUT METAL ANTI -THEFT HOUSING), REPLACING .