Malfunction Indicator Lamp: Testing and Inspection

Malfunction Indicator Lamp (MIL) Function, Checking

Checking function
- Switch ignition on.

MIL must light up.
- If MIL does not light
when ignition is switched on, check wiring to MIL as follows:

Cause: Corrective action:
MIL is not triggered, or does
not light, due to faulty wiring or open circuit.

Switch ignition off.
Connect VAG1598/22 test box.
Connect jumper wire to bridge test box sockets 2 and 17.
Switch ignition on.
MIL must light up.
Switch ignition off.
Check bulb for MIL.

If bulb is OK:
Check wiring for open circuit between MIL and Motronic ECM -J220- using applicable wiring diagram.

If wiring is OK:

Malfunction: Motronic ECM -J220- is faulty; replace.

If MIL lights up when ignition is switched on, continue checking as follows:
- Start engine and let run at idle.
MIL must go out after a few seconds.

If MIL does not go out:
- Check Diagnostic Trouble Code (DTC) memory.

If there are no malfunctions stored in DTC memory:
Cause: Corrective action:
MIL is triggered continuously
due to short circuit to Ground.
- Switch ignition off.
- Connect VAG1598122 test box.
- Check resistance between test box socket 17 and vehicle Ground, specified value: Infinity Ohm (no continuity)

If the specified value is not obtained:
- Check for short circuit to Ground in wiring from Motronic Engine Control Module (ECM) - J220- to MIL.
G- Trace malfunction using applicable wiring diagram and repair as necessary.
If there is no continuity, and no short circuit to Ground:

Malfunction: Motronic ECM -J220- is faulty; replace