DTC 2123

1. With the ignition "OFF", disconnect the Motronic control unit harness connector. The Motronic control unit is located beneath the drip tray, at the center rear of the engine compartment.
2. Connect a suitable volt/ohm meter between terminal 32 and 35 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.

3. Close the throttle.

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

4. Open the throttle fully.

^ The measurement should be less than 1 ohm (continuity).

Throttle Valve Potentiometer:

5. If the measurement is incorrect, disconnect the harness connector at the throttle switch.
6. Check the circuit between terminal 32 of the Motronic control unit and terminal 3 of the throttle valve potentiometer/throttle switch.

^ The measurement should be less than 1 ohm (continuity).

If the measurement is incorrect repair or replace the damaged harness. If the measurement is OK continue.

7. Connect the ohmmeter between terminal 3 and 2 of the throttle switch. Open the throttle fully. Refer to CHASSIS ELECTRICAL DIAGRAMS for terminal designations.

^ The measurement should be less than 1 ohm (continuity).

If the throttle valve potentiometer is properly adjusted (refer to ADJUSTMENT PROCEDURES) and the correct measurements are not obtained the throttle/valve potentiometer is defective. Replace the throttle/valve potentiometer switch.