Introduction

General Instructions/Safety Instructions
The following points must be observed during vehicle diagnosis:
- If one control unit is defective, the entire hydraulic unit must be replaced.
- After troubleshooting or repairs, erase the fault memory with the Porsche System Tester II No. 9588 and carry out a test drive.
- After the test drive, read out the fault memory with the Porsche System Tester II No. 9588 again.

CAUTION:
Danger of damage due to improper handling of batteries and control unit plug connections.
- Always switch off the engine before disconnecting battery terminal connectors
- Never start the engine without a securely connected battery
- Always switch off the ignition before pulling off or pushing on plug connections for the control units or other electronic components
- Always disconnect the negative terminal of the battery before carrying out welding work on the vehicle.

New Speed Sensor
With the ABS 5.7, new active speed sensors have been used. They are provided with semiconductor elements and work on the Hall-effect principle. Connectors are of swap-proof design.

CAUTION: Risk of destruction of speed sensors when measuring resistance.

Risk of destruction of speed sensors if connector pins are swapped:
- Do not perform resistance measurements on the speed sensor
- Observe the correct polarity when connecting

Communication Between Control Unit And Porsche System Tester II No. 9588
The following conditions must be present to establish communication between the vehicle electrical system control unit and the Porsche System Tester II No. 9588:
- Porsche System Tester II No. 9588 connected to data link connector
- Ignition on
- Battery positive voltage > 11 V
- Power supply for ABS control unit is OK

General Information On The Fault Memory
- The fault memory of the control unit can save up to three different faults simultaneously.
- If all three fault memory locations are occupied, the new fault overwrites the oldest fault.
- The fault memory content is maintained even in the removed state
- Faults in the control unit can only be reset after an "ignition off - on" reset

Diagnostic Conditions
The fault can be identified only if the requirements listed under "Diagnostic conditions" are met. For this reason, the specified procedure must be observed after a fault is repaired:
1. Erase fault memory
2. Satisfy the requirements listed under 'Diagnostic conditions'
3. Read out fault memory again

Possible Causes Of Fault
The possible causes for the fault are listed here. Please note that in certain circumstances further faults can be stored in the fault memory after troubleshooting (e.g. if plugs are disconnected), After carrying out repairs, read out the fault memory of all control units and erase any faults.

Diagnosis/Troubleshooting
The fault memory Info key F3 on the Porsche System Tester II No. 9588 can be used to access the extended fault memory. This information should be saved using the F4 key and printed out.

The following information can be displayed:

- Fault type
The following fault types are possible:
- No details available
- Short circuit to B+
- Short circuit to ground
- Signal implausible
- No signal change
- Open circuit/short circuit to B+
- Open circuit/short circuit to ground
- Open circuit
- Below lower limit
- Above upper limit

- Fault status
The following status types are possible:
- Present - at time of the last control-unit routine
- Not present - at time of the last control-unit routine