Checking the Intake Manifold Heater

PROCEDURE

Heating grid check: with the engine cold, disconnect the connector to the heating grid under the intake manifold (located on the side of the mixture preparation unit).

Connect an ohmmeter between the heating grid cable and ground. If the reading is 0.25 – 0.50 Ω, the heating grid is serviceable.

If no ohmmeter is available, remove the mixture preparation unit with the engine cold, switch the ignition on, and check whether the grid pins heat up by touching them with a wet finger.

If the heating grid does not heat up even though the resistance is correct, the relay may be faulty.

Checking the thermal switch: (see Mono-Motronic Fuel Injection System).

Checking the relay – refer to Body Electrical System.

Air Cleaner Housing for 66 kW Engine with Mono-Motronic Fuel Injection:
1 – warm air intake;
2 – cold air intake;
3 – diaphragm unit;
4 – air flap actuating rod;
5 – temperature regulator.

Heating grid (3) in intake manifold (4) with connecting wire (5).