Cis MOTRONIC: Potentiometer
- Ensure engine is at normal operating temperature. Connect Test Adapter (VW 1501) between potentiometer (on fuel distributor) and harness. See Fig 1 . Connect voltmeter to test adapter connectors 1 and 3. Turn on ignition. Reading should be 4.35-5.35 volts.
- Switch voltmeter leads to test adapter connectors 2 and 3. Start engine and let idle. Engine cooling fan must NOT come on during this test. Reading should be .4-.9 volt. If reading is slightly out of tolerance, correct by adjusting the potentiometer trim screw. If correction is not possible, replace potentiometer.
- When replacing potentiometer, DO NOT touch resistance strip or contact whiskers inside potentiometer. Loosely install potentiometer. Connect voltmeter to test adapter connectors 2 and 3. Turn ignition on but DO NOT start engine. Measure voltage. Reading should be 10-100 mV. Adjust potentiometer to read correctly by turning trim screw.
- Pull adjusting slide on Sensor Plate Gauge (VW 1348/1) up to upper stop. Place gauge centrally on edge of airflow sensor, with pointer pointing toward fuel distributor. See Fig 2 . Push adjusting slide down to stop. Rotate setting screw until base of magnet contacts sensor plate mounting screw.
- Pull adjusting slide up to first stop (idle position). Adjust potentiometer set screw to obtain .5-.8 volt.
- Remove sensor plate gauge and install intake air boot. Start and run engine until cooling fan has cycled at least once. DO NOT take voltage readings while engine is running.
- Stop engine and turn on ignition. Potentiometer voltage should be .4-.9 volt. If voltage reading is out of range, repeat step 2). Replace airflow sensor if correct voltage is still unattainable after performing all procedures.
NOTE:
Coolant temperature sensor terminal identifications are imprinted on connector.