Diagnosis troubleshooting alarm system

The alarm control unit is diagnosable. It can be read out only with System Tester 9288.

The menu includes the following functional groups:

Fault memory

Drive links

- Input signals

- Country codes

- Results

- System check Note

For some of the faults, two types of causes must be distinguished:

- The fault displayed is an actual fault that has to be remedied.

The fault displayed is a fault condition that has been caused deliberately, e.g. by leaving the open glove compartment open.

Troubleshooting requires that the person performing the tests

- is familiar with the location of components, function and technical relationship of the systems being tested (refer to Model Information)

- is able to read and evaluate Porsche wiring diagrams

- knows the functions of circuits and relays

- is capable of using testers and of evaluating the test results.

Tools required for troubleshooting: Special Tool 9540


The Special Tool is required because connector II is fitted with miniature terminals. To avoid damaging the terminals, always use the Special Tool for the tests. When checking for continuity, attach connector to wiring harness only. When checking signals and voltages, attach connector to wiring harness and control unit.

Pin assignments of alarm control unit connector

1995 993 Vale Covers

Connector I


4 - Anti-drive off feature

7 - Interior light

8 - Turn signal left

9 - Turn signal right

11 - Motor „Closed" Actuator door lock

12 - Motor „Open" Actuator door lock

14 - LED front passenger's door

15 - LED driver's door

Connector II


1 - Activate / closed

2 - Deactivate / open

3 - Rear lid contact

4 - Tailgate lock

5 - Hood contact

6 - Speedo signal Term. A

10 - Central locking system position switch

11 - Central locking system button

12 - Central locking system position switch

16 - Glove compartment contact 17-Input 3

20 - Central locking system button light

21 - Door contacts

24 - External electronics

Fault memory

Overview of possible displays

Control unit defective

Glove comp, open during activation

Voltage failure Term. 30 with active alarm system

Input 2 to ground during activation

Voltage failure during alarm output

Central lock button closed during activation

Position of the drives unplausible

Input 1 to ground during activation

Door(s) open during activation

Input 3 to positive during activation

Engine compartment open during activation

Position switch on drive closed during activation

Luggage comp. open during activation

Position switch on drive open during activation


(closed loop) interrupted during activation

Radio contact to ground during activation

Tailgate lock switch closed during activation

Fault, Fault Code Possible Causes, Elimination, Remarks


After a fault in the alarm system has occurred and after it has been remedied, the fault memory must be erased.

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