Introduction

Introduction

The manual contains the diagnosis for the following system:

Instrument cluster

Electrical power supply - general

Work instructions after disconnecting the battery
Effects of disconnection or total discharge of the battery on electrical systems in the vehicle, subsequent measures:
- Never disconnect battery with engine running.
- Never start engine without securely connected battery.
- Never use a boost charger to start the engine.
- Whenever possible, use jump leads with overvoltage protection.
- Plug connectors of control modules or other electronic components must never be connected or disconnected with the ignition switched on. Exception: vehicles with the additional equipment M 536 (alarm siren with tilt sensor).

Note concerning M 536:
In order to avoid triggering the alarm siren (installed on right next to the battery) of vehicles with M 536, terminal 86 S of the battery must be disconnected with the ignition on (all loads must be switched off beforehand).

Instrument cluster
The trip counter is set to 0 when the power supply is disconnected.

Clock:
Depending on the software version, the clock is set to 12:00 a.m. or 1:00 a.m. when the power supply is disconnected.

Remedy:
Enter the current time again.

On-board computer
Disconnection of the vehicle battery deletes the memories for average speed and average consumption. As a result, the displayed range on remaining fuel can be markedly different or even 0. The outside temperature indicator loses its memory effect. In other words, the indicated outside temperature can be too high due to the heat radiated when the vehicle is hot.

Fuel level display

Only 911 Carrera 4 (996) and GT3 are affected:
If the power supply is interrupted due to a discharged or disconnected battery and a quantity of less than 19 I remains in the tank, the calculated value for the range on remaining fuel will be deleted or falsified in the instrument cluster. If less than 10 I of fuel remains in the tank, the fuel level warning light might not be activated. If the power supply is restored with the fuel level at less than 19 I, it is possible that the fuel level display may subsequently display too much in some 996 Carrera 4 and GT3 vehicles.

This may lead to the vehicle breaking down.

Remedy in these vehicles:
Refill at least 19 I of fuel. The fuel level sensor is then in operating range and its display precision is guaranteed.

Radio
The radio reverts to the Code function when the battery is disconnected and is thus no longer ready for operation.

Remedy:
Input the radio code. If the code card is unavailable, the radio code can be read from the DME control module (under "Vehicle data"). This code is also available from the Porsche IPAS.

PCM
- The PCM reverts to the Code function when the battery is disconnected and is thus no longer ready for operation.
- When the power supply is disconnected, the built-in GPS receiver loses the so-called almanac containing the satellite orbital paths.
- The date and time are no longer displayed on the display after the power supply is disconnected.
- If the telephone card was inserted and the telephone was ready for operation, the telephone is subsequently disabled.

Remedy
- Input the PCM code. If the code card is unavailable, the PCM code can also be read from the DME control module (under "Vehicle data"). This code is also available from the Porsche IPAS.
- Switch on the PCM with a free panoramic view for approx. 20 minutes (to load GPS almanac).
- The date and time are also adopted once the GPS almanac has been loaded; it may be necessary to change over to summer time (daylight-saving time). This time is transferred to the instrument cluster. If the time is then manually changed by means of the instrument cluster, this time is adopted by the PCM and synchronised with GPS time.
- The stored stations are displayed again when station buttons 1 to 6 are pressed.
- The telephone is enabled again when the telephone PIN code is entered with the SIM telephone card inserted.