Audi Workshop Service and Repair Manuals

The engine speed signal is required for the rev counter, air conditioner and automatic gearbox.

However, since the signal cannot be read in the form in which it is generated by the engine speed sensor (G28), it must be processed by the engine control unit.

Identify the engine speed signal as follows:

Instrument cluster:

• ‒ Observe rev counter reading.

• Specified value: The current engine speed must be displayed.

Air Conditioner

The signal is monitored by the air conditioner self diagnosis function (fault memory, read measured value block).

Signal testing

=> Heating, Air Conditioner; Repair group 01

• Specified value: The current engine speed should be displayed in the measured value block.

Automatic gearbox

The signal is monitored by the self-diagnosis function (fault memory, read measured value block) of the automatic gearbox control unit.

Signal testing

=> Automatic Gearbox; Repair group 01

• Specified value: The current engine speed should be displayed in the measured value block.

If the engine speed signal specified value is not achieved for all "consumers", the following faults are possible:

• ◆ Open circuit or short in wiring between diesel direct injection system control unit and wiring harness connector.

=> Current Flow Diagrams, Electrical Fault-finding and Fitting Locations binder

• ◆ Short circuit between connector in wiring harness and "consumer".
• ◆ Diesel direct injection system control unit defective

If the specified value is obtained by at least one of the engine speed signal "consumers", the following faults are possible:

• ◆ Open circuit between connector in wiring harness and "Consumer".
• ◆ "Consumer" defective.