Initial Inspection and Diagnostic Overview

Software Level B 01

The airbag system is continuously monitored by a diagnosis unit in the control unit. If a fault occurs, it is indicated by a script in the instrument cluster.

In the event of a fault, the central warning light and this script come on.

The airbag script comes on for approx. 5 seconds* after the ignition is switched on and then goes off again.

Should the warning lamp come on again later, this indicates a fault in the airbag system. The fault can be read out with System Tester 9288.

Note: The control unit needs approx. 70 seconds to identify all faults in the system, and the ignition must therefore be switched on for at least this time to ensure that all possible sources of defects can be checked.

After a fault in the airbag system has been identified and rectified, the fault memory must be erased.

If any components are exchanged, this must be noted in the warranty and maintenance booklet. The document number should be attached in the free space provided. The document number is shown on an adhesive label which can be torn off the spare part.

Following an accident in which the airbag system was activated, the following components must be removed and replaced:

- control unit

- both front impact sensors

- contact unit

- both airbag units

If non-activated airbag units have to be removed, they must be ignited electrically before being disposed of.

* 2.5 seconds as of manufacturing date June 22, 1992.

Accessing the menu items

If the airbag control unit is not displayed by the tester, check the following items:

- 2-pin connector T 42 (in airbag control unit area)

- K and L wires from control unit to diagnosis socket (continuity check)

- If no diagnosis is possible, the following items must be checked:





- L wire: The voltage at pin 7 of the diagnosis socket must be > 8 V when the ignition is switched on.

- K wire: The voltage at pin 8 of the diagnosis socket must be > 8 V when the ignition is switched on.

Assignment:

7 - L wire

8 - K wire

10 - Ground

13 - Terminal 15

Possible fault causes if voltage is < 8 volts

- Short to ground or open circuit of wiring.

- A defective, diagnosable control unit connected to the above wires.

- Tester defective.

- Voltage supply at diagnosis connector is missing.

Before troubleshooting can be carried out correctly, the person concerned must be:

- familiar with the component locations and the function and technical relationship of the systems to be checked (Model Information).

- be able to read and evaluate Porsche circuit diagrams.

- understand the function of the electrical circuits and relays.

- be capable of operating and assessing the information supplied by the test gear.

Important: If the tester display indicates that a component is defective, the fault may not necessarily be found in the component indicated but may be in the associated control unit or the connecting circuits (electrical paths) between the component and the control unit. Before the fault memory has been read out, no troubleshooting involving the pulling off of plugs or similar is to be carried out, as this could also be stored as a fault in the memory.

Note: The fault code shows two types of fault:

- Fault still present.

- Fault currently not present.

Faults are stored as currently not present if they occur briefly while the ignition is switched on, but are no longer present when the ignition is switched off.

Faults still present are those which are permanent or remain present when the ignition is switched off. Do not assume that the fault in the readout is actually present or clearly identifiable during the check.

A fault being memorized may for example be due to tampering with the airbag system wiring while the ignition was switched on.

In the case of faults currently not present it is also important to determine the cause of the fault in order to prevent it from recurring and to avoid replacing parts unnecessarily. Check the entire length of the airbag system wiring for damage (wires damaged or trapped).

Tools





Special Tool 9516





Special Tool 9516/1

Special Tools 9516 and 9516/1 are used to check the ignition pill circuits.

If there is a fault in the ignition pill circuits, attach Special Tool 9516 in place of the airbag units, then erase the fault memory. Switch the ignition off and on again.

The fault can then be identified by means of the diagnosis unit in the airbag control unit.

If the warning light no longer indicates a fault, the airbag unit is defective and must be replaced.

If the warning light again indicates a fault, the control unit or the wiring are at fault.

A fault in ignition pill circuit 1 may also be caused by the contact unit. Disconnect the wiring harness from the contact unit and attach Special Tool 9516/1 in place of the contact unit. Erase the fault memory. Switch the ignition off and then on again. If the warning light no longer indicates a fault, the contact unit is defective; if the warning light again indicates a fault, the control unit or the wiring are at fault.

Note: For safety reasons, never drive the vehicle with the special tools installed in place of the airbag units.

Special Tool 9541





Special Tool 9541 is used to check the wiring of the airbag system. It is attached in place of the control unit. For safety reasons, the wiring to the ignition pills cannot be checked with this tool.

Failure time

The Failure Time menu item displays the time elapsed since the first fault was stored in the fault memory.

The maximum time that can be displayed is 99 hours and 59 minutes. If this time is exceeded, the ">" sign is displayed ahead of the hours.

Results

The Results menu item displays the crash data.