Functional check

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Switch ignition on. Malfunction Indicator Lamp (MIL) must light up.

If Malfunction Indicator Lamp (MIL) does not light up with the ignition switched on:

Check wiring from Motronic Engine Control Module (ECM) J220 to Malfunction Indicator Lamp (MIL) as follows:

Cause:		Corrective Action:
Malfunction Indicator Lamp (MIL) is not activated or does not light up due to open circuit.		Switch ignition off. Connect test box VAG 1598/31. Bridge test box sockets 2 and 47. Switch ignition on. Malfunction Indicator Lamp (MIL) must light up. If Malfunction Indicator Lamp (MIL) does not light up: Switch ignition off. Check instrument cluster. If instrument cluster is OK: Locate and eliminate short or open circuit in wiring from Motronic Engine Control Module (ECM) J220 to Malfunction Indicator Lamp (MIL) using wiring diagram.
		If wiring to Malfunction Indicator Lamp (MIL) is OK:
Malfunction cause	→	Motronic ECM J220 is faulty. Replace Motronic ECM J220 → Engine Control Module (ECM), replacing .

If Malfunction Indicator Lamp (MIL) lights up with the ignition switched on, continue check as follows:

Start engine and run at idle. MIL must go out after a few seconds.

If the Malfunction Indicator Lamp (MIL) does not go out:

Check DTC memory. If necessary, repair any malfunctions and erase DTC memory → Diagnostic Trouble Code (DTC) memory, checking and erasing (scan tool functions 02 and 05) .

If no DTCs are stored:

Cause:		Corrective Action:
Malfunction Indicator Lamp (MIL) is permanently activated by short to Ground (GND).		Switch ignition off. Connect Test box VAG 1598/31. Control module is not connected by this action. Check wire resistance between test box socket 47 and vehicle Ground (GND): Specified value: infinite Ohm (∞ Ω) If the specification is not obtained: Short to Ground (GND) in the activation wire from Motronic ECM J220 to Malfunction Indicator Lamp (MIL). Locate and eliminate this malfunction using wiring diagram.
		If the specification infinite Ohm (∞ Ω)~ is obtained and no short to Ground (GND) can be found:
Malfunction cause	→	Motronic ECM J220 malfunctioning. Replace Motronic ECM J220 → Engine Control Module (ECM), replacing .

Display readiness code → Readiness code (function 15), displaying .

If DTC memory has been erased, the readiness code must be generated again → Readiness code (function 15), generating .