A.Detailed Fault Diagnosis With System Tester 9288.

If a fault is displayed in the perimeter, precise diagnosis with use of the additional menu points of tester 9288 must be performed.

This applies for all fault codes listed in secton B.

Note: The additonal menu points cannot be activated on control units with Part Number 964 659 047 00. For diagnosis control unit 964 659 047 01 (from '91 (M) model year) can be used.

When installing control unit Part Number 964 659 047 01 in cars prior to'91 (M) models, heater fans and engine compartment fan are running in the emergency functon (with heater on heater fans-half value, engine compartment fan - position 2). This condition does not affect testing. Therefore, the contols should be set to max. cold.

Refer to Workshop Manual 911 Carrera 2/4 Volume VI, page 87-27 for wiring harness modification when replacing "...00" control unit with "...01 " control unit for reasons other than diagnosis.

Sensor Faults: Menu point "Input Signals". The values of all connected sensors can be displayed and compared to published values. (Workshop Manual D80/87).

Drive Motor Faults: Menu point "Drive Links". The operation of each drive motor can be checked.


Fan Motor Faults: Menu point "Drive Links". Each fan motor can be activated. A bar graph displays the voltage for engine compartment A/C condensor and oil cooler fan motor. Operation of left and right heater fan motors can be checked by observing airflow and fan noise.