MIL functional check

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 1999 Volkswagen Jetta, 1998 Volkswagen Jetta, 1997 Volkswagen Passat, 1997 Volkswagen Jetta, and 1996 Volkswagen Passat. However, it is still accessible from the selected car via links, so may be relevant.

Switch ignition on.
- MIL must come on (light up) and stay on until the engine has started
- Glow plug indicator light may also come on during the pre-glow period when the engine is cold
If the MIL does not come on (with ignition switched on):

Fig 1: Locating Malfunction Indicator Lamp (MIL) K83

Check MIL as follows in SYMPTOM - MIL DOES NOT COME ON (WITH IGNITION SWITCHED ON) .

SYMPTOM - MIL DOES NOT COME ON (WITH IGNITION SWITCHED ON)

Symptom:	Corrective action:
MIL does not come on, due to an open circuit	Switch ignition off. Connect VAG1598/18 test box. Bridge test box sockets 1 and 60. Switch ignition on. MIL must light-up If MIL does not light-up: Switch ignition off. Check MIL bulb. If the bulb is OK: Locate and eliminate short or open circuit between Diesel DFI ECM -J248- and MIL, using wiring diagram.
Cause of malfunction	If there is no malfunction in the MIL wiring: diesel DFI ECM is faulty. Replace Diesel DFI ECM -J248-. Erase DTC memory. Create readiness code.

Symptom:

Corrective action:

MIL does not come on, due to an open circuit

Switch ignition off.
Connect VAG1598/18 test box.
Bridge test box sockets 1 and 60.
Switch ignition on.

MIL must light-up

If MIL does not light-up:

Switch ignition off.
Check MIL bulb.

If the bulb is OK:

Locate and eliminate short or open circuit between Diesel DFI ECM -J248- and MIL, using wiring diagram.

Cause of malfunction

If there is no malfunction in the MIL wiring:
diesel DFI ECM is faulty.

Replace Diesel DFI ECM -J248-.
Erase DTC memory.
Create readiness code.

If the MIL does come on (with ignition switched on):

Start engine and let idle.

MIL must go out after a few seconds.

If the MIL does not go out:

Check DTC memory, see CHECK DTC MEMORY (SCAN TOOL FUNCTION 02) .

If there are no DTCs stored: See SYMPTOM - MIL DOES NOT GO OUT (WITH IGNITION SWITCHED ON) .

SYMPTOM - MIL DOES COME NOT GO OUT (WITH IGNITION SWITCHED ON)

Symptom:	Corrective action:
MIL is permanently activated by short to Ground	Switch ignition off. Connect VAG1598/18 test box. Check resistance between test box socket 60 and vehicle Ground; specification: INFINITY Ω (no continuity) If the specification is not obtained: Locate and eliminate short circuit to Ground between Diesel DFI ECM -J248- and MIL, using wiring diagram.
Cause of malfunction	If the specification (infinity ohms) is not obtained, and there is no short to Ground: Diesel DFI ECM is faulty. Replace Diesel DFI ECM -J248-. Erase DTC memory. Create readiness code.

Symptom:

Corrective action:

MIL is permanently activated by short to Ground

Switch ignition off.
Connect VAG1598/18 test box.
Check resistance between test box socket 60 and vehicle Ground; specification: INFINITY Ω (no continuity)

If the specification is not obtained:

Locate and eliminate short circuit to Ground between Diesel DFI ECM -J248- and MIL, using wiring diagram.

Cause of malfunction

If the specification (infinity ohms) is not obtained, and there is no short to Ground: Diesel DFI ECM is faulty.

Replace Diesel DFI ECM -J248-.
Erase DTC memory.
Create readiness code.