Checking accelerator position sender -G79: Audi 1.9 TDI (1Z, AHU)

AHU
Special tools and workshop equipment required

V.A.G 1526 A
V.A.G 1594 A
V.A.G 1598/18
VAS 5051 with VAS 5051/1 and
VAS 5051/2

or

V.A.G 1551 with V.A.G 1551/1

Detach cover from relay plate with fuse box in plenum chamber.
Use diagnostic wire VAS 5051/1 and diagnostic adapter VAS 5051/2 to connect up vehicle diagnostic, testing and information system VAS 5051. Alternatively, use can be made ofdiagnostic wire V.A.G 1551/1 to connect up fault reader V.A.G 1551.

Note:

The following description refers solely to implementation of self-diagnosis using fault reader V.A.G 1551.

Proceed in line with equipment operating instructions if use is made of vehicle diagnostic, testing and information system VAS 5051.

With ignition switched off, attach black connector to black diagnostic connection.

V.A.G SELF-DIAGNOSIS
HELP
1 - Rapid data transfer 1)
2 - Flash code output1)
Indicated on display:

1)
Displayed alternately

Note:

If display remains blank, check power supply and wiring in line with current flow diagram.

Attach white connector to white diagnostic connection (blue connector is not used).
Switch on ignition.
Press Print key to switch on printer
(lamp in key lights).
Press key 1 for "Rapid data transfer".

Rapid data transfer
HELP
Enter address word XX
Indicated on display:

Enter "01" for address word "Engine electronics" and confirm with Q key.

028906021DQ
1.9l
R4
EDC
SG
D05.
⇒
Code 00005
WSC 00000
Fault reader V.A.G 1551 displays control unit identification (example).

To switch to next step, press ⇒ key twice.

Rapid data transfer
HELP
Select function XX
Indicated on display:

Enter "08" for "Reading measured value block" function and confirm with Q key.

Reading measured value block
Q
Enter display group number XXX
Indicated on display:

Enter "002" for "Display group number 002" and confirm with Q key.

Reading measured value block 2
⇒
0 rpm
0.0 %
0
1
0
18.4 5C
Indicated on display:

Check display in zone 2.
Specification: 0.0 % (accelerator pedal not pressed)

Check display in zone 3.
Specification:
0 1 0 (accelerator pedal not pressed)
0 0 0 (accelerator pedal pressed)

Slowly floor accelerator pedal.

Reading measured value block 2
⇒
0 rpm
100.0 %
0
0
0
18.4 5C
Indicated on display:

Specification: Display in zone 2 must increase steadily to 100 % (accelerator floored)

If reading does not match initial/ final specification, adjust accelerator position sender -G79 => Page
20-43
.

If display does not change or only irregularly:

Checking internal resistance

Switch off ignition.
Remove driver's storage compartment.

=> General Body Repairs, Interior; Repair Group 68; Storage compartments/covers and trim panels; Removing driver's storage compartment
General Body Repairs, Interior
Storage compartments/covers and trim panels
Removing driver's storage compartment

Unplug connector of accelerator position sender -G79 in footwell at accelerator pedal.

Connect up multimeter for resistance measurement to the following contacts of the connector for the accelerator position sender -G79.

Contacts · Accelerator pedal · Specification
1 + 3 · not pressed · 0.6 ... 1.4 kω
2 + 3 · not pressed · 0.6 ... 1.4 kω
4 + 6 · not pressed · 0.6 ... 1.4 kω
pressed · ∞ ω

If readings do not match specifications, replace accelerator position sender -G79.

Checking wiring

With ignition switched off, connect test box V.A.G 1598/18 to connector of engine control unit.

=> Diesel Direct Injection and Glow Plug System (TDI 4-cyl.); Repair Group 23; Servicing Diesel Direct Injection System; Wiring and Component Check with Test Box V.A.G 1598/18
Diesel Direct Injection and Glow Plug System (TDI 4-cyl.)
Servicing Diesel Direct Injection System
Wiring and Component Check with Test Box V.A.G 1598/18

Remove driver's storage compartment.

=> General Body Repairs, Interior; Repair Group 68; Storage compartments/covers and trim panels; Removing driver's storage compartment
General Body Repairs, Interior
Storage compartments/covers and trim panels
Removing driver's storage compartment

Unplug connector of accelerator position sender -G79 in footwell at accelerator pedal.

Check for open circuit and short to earth/positive in the following connector wires.

Connector / Contact · Test box V.A.G 1598/18 / Socket
1 · 15
2 · 57
3 · 55
4 · 65
6 · 1, 24, 46

If necessary, eliminate open circuit in wiring/short circuit.

If wiring is OK:

Replace engine control unit.

=> Diesel Direct Injection and Glow Plug System (TDI 4-cyl.); Repair Group 23; Servicing Diesel Direct Injection System; Replacing engine electronics control unit
Diesel Direct Injection and Glow Plug System (TDI 4-cyl.)
Servicing Diesel Direct Injection System
Replacing engine electronics control unit