DTC 2112

1. With the ignition "OFF", disconnect the Motronic control unit harness connector. The Motronic control unit is located beneath the drip tray, at the left rear (drivers side) of the engine compartment.
2. Connect a suitable volt/ohm meter between terminal 27 and 29 of the Motronic control unit harness connector. Set the volt/ohm meter to ohms.

Special Tools:

CAUTION: Avoid damaging the delicate connectors within the control unit harness connector. A simple set of test leads can be fabricated using flat connectors (part # VW N 17 457 2) or equivalent, and a pair of alligator clips.

^ The correct measurement should be less than 2 ohms.

Ignition Reference Sensor:

3. If the resistance is greater than 2 ohms disconnect the ignition reference sensor.
4. Check the circuits from terminal 27 and 29 of the control unit harness connector to terminal 1 and 2 of the reference sensor harness connector.

^ Approx. 0 ohms should be present (continuity) in both circuits.

If continuity is not present repair or replace the damaged harness as necessary.
If the measurement is correct check the resistance of the ignition reference sensor.

5. Measure the resistance between terminal 1 and 2 of the ignition reference sensor.

^ The correct measurement should be less than 2 ohms.

6. Measure the resistance between terminal 1 and 3 of the ignition reference sensor.

^ The correct measurement should be infinite ohms (no continuity).

If the correct measurements are not obtained replace the ignition reference sensor.
If the correct measurement is obtained the problem may be intermittent (recheck the harness and connections), or the CIS-E control unit may be defective.