Malfunction Indicator Lamp (MIL), Checking

Malfunction Indicator Lamp (MIL), Checking

Special tools and equipment

- VAG 1598/31 test box
- Multimeter (Fluke 83 or equivalent)
- VW1594 adapter set
- Wiring diagram

Test requirements







- Fuses 10 and 29 OK
- Battery (B+) voltage at least 11.5 V

Functional check
- Switch ignition on.
The Malfunction Indicator Lamp (MIL) must light up.

If the 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:
Malfunction Indicator Lamp (MIL) is not activated or does not light up due to open circuit.

Corrective Action:
- Switch ignition off.
- Connect VAG1598/31 test box.
- Bridge test box sockets 2 and 47.
- Switch ignition on.
Malfunction Indicator Lamp (MIL) must light up.
If the 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.

Malfunction cause
If wiring to Malfunction Indicator Lamp (MIL) is OK:
Motronic Engine Control Module (ECM) -J220- is faulty.
- Replace Motronic Engine Control Module (ECM) -J220-.

If the Malfunction Indicator Lamp (MIL) lights up with the ignition switched on, continue check as follows:
- Start engine and run at idle.
The Malfunction Indicator Lamp (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.

If no DTCs are stored:

Cause:
Malfunction Indicator Lamp (MIL) is permanently activated by short to Ground (GND).

Corrective Action:
- Switch ignition off.
- Connect VAG1598/31 test box.
The control module is not connected by this action.
- Check wire resistance between test box socket 47 and vehicle Ground (GND):
Specified value: Infinite Ohm
If the specification is not obtained:
Short to Ground (GND) in the activation wire from Motronic Engine Control Module (ECM) -J220- to Malfunction Indicator Lamp (MIL).
- Locate and eliminate this malfunction using wiring diagram.

If the specification infinite Ohm is obtained and no short to Ground (GND) can be found:

Malfunction cause
Motronic Engine Control Module (ECM) -J220- malfunctioning.
- Replace Motronic Engine Control Module (ECM) -J220-.

- Display readiness code.

If DTC memory has been erased or the Motronic Engine Control Module (ECM) -J220- was disconnected from permanent battery (B+) voltage, the readiness code must be generated again.