Checking accelerator pedal position sender G79 — AUDI

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