Audi Workshop Service and Repair Manuals

Checking accelerator pedal position sender -G79- Special tools and workshop equipment required t  -V.A.G 1526 A- t  -V.A.G 1594 A- t  -V.A.G 1598/31-

t  Vehicle diagnosis and service information system -VAS 5052- Test sequence   Note Both the accelerator pedal position sender -G79- and the accelerator pedal position sender 2 -G185- are located at the accelerator pedal and provide the engine control unit with completely independent information on the driver input. Both senders are accommodated in a single housing. –  Connect up the vehicle diagnostic and service information system -VAS 5052- and select the engine electronics control unit. When doing this, the ignition must be switched on. –  Select the function “Read measured value block”. –  Select “Display group number 062”. –  Check the specifications for the electronic throttle potentiometer voltages in display zones 3 and 4.

	Display zones
	1	2	3	4
Display group 062: Electronic throttle potentiometer voltages
Display	xx %	xx %	xx %	xx %
Display	Throttle valve angle (angle sender 1)	Throttle valve angle (angle sender 2)	Accelerator pedal position sender 1	Accelerator pedal position sender 2
Specification	3...93 %	97...3 %	12...97 %	4...49 %

Note The engine control unit converts the voltage values of the angle senders into a percentage referenced to 5 V and displays these percentage values (5 V supply voltage corresponds to 100 %). –  Observe display zones 3 and 4. –  Slowly floor the accelerator pedal. The percentage display in zone 3 must increase steadily. The tolerance range 12...97 % is not fully utilised in the process. The percentage display in zone 4 must also increase steadily. The tolerance range 4...49 % is not fully utilised in the process.   Note The value displayed in zone 3 must always be roughly twice that in display zone 4. If the displays are not as described: –  Check voltage supply and wiring of accelerator pedal senders. Checking voltage supply to accelerator position senders –  Remove driver's storage compartment → Rep. Gr.68. –  Unplug the connector from the accelerator pedal position sender -G79-. –  Switch on ignition.

–  Connect up the multimeter (voltage measuring range) as follows:

Connector Contact	Specification
1 + earth	approx. 5 V
1 + 5	approx. 5 V
2 + earth	approx. 5 V
2 + 3	approx. 5 V

If the specifications are obtained: –  Check the signal wires. If the specifications are not obtained: –  Check wiring between engine control unit and accelerator position senders. Checking wiring –  Connect the test box -V.A.G 1598/31- to the wiring harness to the engine control unit, but do not connect the actual engine control unit → Chapter.

–  Check for open circuit and short to earth or positive in the following wiring:

Connector Contact	Test box -V.A.G 1598/31- Socket
1	72
2	73
3	36
4	35
5	33
6	34

–  Eliminate open circuit in wiring/short circuit if necessary. If no fault is found in the wiring: –  Renew accelerator position senders: Fuel supply system, petrol engines → Rep. Gr.20.