Checking accelerator position sender G79 — VW

Checking
accelerator position sender
G79
Special tools and workshop equipment required
Hand multimeter
V.A.G 1526A
or
hand multimeter
V.A.G 1526C
Auxiliary measuring set
V.A.G 1594A
or
auxiliary measuring set
V.A.G 1594C
121-pin adapter cable
V.A.G 1598/31
Not illustrated:
Fault reader
V.A.G 1551
or
vehicle diagnostic tester
V.A.G 1552
with
diagnosis cable
V.A.G 1551/3C
Current flow diagram
Test procedure
Right-hand drive vehicles
Left-hand drive vehicles
Anchor
Connect
fault reader
V.A.G 1551
or
vehicle diagnostic tester
V.A.G 1552
and select engine electronics control unit with
“address word”
01. The ignition must be switched on for this purpose.
Indicated on display:
Rapid data transfer HELP
Select function XX
Press keys
0
and
8
for function
“Read measured value block”
and confirm entry with
Q
key.
Indicated on display:
Read measured value block HELP
Input display group number XXX
Press buttons
0
,
0
and
2
for
“display group number 2”
and confirm entry with
Q
button.
Check accelerator position display in display zone 2. The accelerator pedal must not be depressed. Specification: 0.0%
Read measured value block 2 ->
0 rpm 0.0 % 0 1 0 18.4 °C
In addition check the idling speed switch display in display zone 3. The middle position must show 1. Display: 010
Depress accelerator pedal slowly until fully down, and observe display zones 2 and 3.
Read measured value block 2 ->
0 rpm 100.0 % 0 0 0 18.4 °C
Display zone 2: The accelerator pedal position value must increase continuously. Specification at full throttle position: 100 %
Display zone 3: The middle position must change to 0. Display: 000
Note
The kickdown switch pressure point must be distinctly noticeable before the full throttle stop.
End specification value not achieved:
Press the
→
button.
Press buttons
0
and
6
for function
“End data transfer”
and confirm entry with
Q
button.
Switch off ignition.
Adjust
accelerator position sender
G79
Chapter
.
Display does not change or is erratic:
Check
accelerator position sender
G79
as follows:
Press the
→
button.
Press buttons
0
and
6
for function
“End data transfer”
and confirm entry with
Q
button.
Switch off ignition.
Remove cover in footwell (driver side).
Disconnect 6-pin connector for
accelerator position sender
G79
.
Measure resistance of sender between contacts 1+3 of connector.
Specification: accelerator pedal in idling position: 0.8…1.4 kΩ
Measure resistance of sender between contacts 2+3 of connector.
Specification: accelerator pedal in idle position: 0.8…1.4 kΩ
Check
idling speed switch
F60
in
accelerator position sender
G79
: To do this, measure resistance between connector contacts 4+6.
Specification: accelerator pedal in idle position: max. 0.8…1.2 kΩ accelerator pedal depressed: ∞ Ω
Measure resistance of sender between contacts 5+6 of connector.
Specification: accelerator pedal in idle position: ∞ Ω accelerator pedal depressed: 0.8…1.2 kΩ
If the specifications are not attained:
Renew
accelerator pedal position sender
G79
Item
.
Read fault memory.
If the specifications are attained:
Remove wiper arms and cowl panel:
Rep. Gr.
92
Connect
121-pin adapter cable
V.A.G 1598/31
to control unit wiring harness. The engine control unit remains disconnected.
Remove cover in footwell (driver side).
Disconnect 6-pin connector for
accelerator position sender
G79
.
Check wiring between test box and connector for open circuit referring to current flow diagram.
Contact 1 + socket 69
Contact 2 + socket 12
Contact 3 + socket 50
Contact 4 + socket 70
Contact 5 + socket 63
Contact 6 + socket 51
Wire resistance: max. 1.5 Ω.
Also check wiring for short to one another, short to earth and short to battery positive.
Specification: ∞ Ω.
If no fault in wiring is detected:
Renew
diesel direct injection system control unit
J248
Chapter
.
Left-hand drive vehicles
Connect
fault reader
V.A.G 1551
or
vehicle diagnostic tester
V.A.G 1552
and select engine electronics control unit with
“address word”
01. The ignition must be switched on for this purpose.
Indicated on display:
Rapid data transfer HELP
Select function XX
Press keys
0
and
8
for function
“Read measured value block”
and confirm entry with
Q
key.
Indicated on display:
Read measured value block HELP
Input display group number XXX
Press buttons
0
,
0
and
2
for
“display group number 2”
and confirm entry with
Q
button.
Check accelerator position display in display zone 2. The accelerator pedal must not be depressed. Specification: 0.0 %
Read measured value block 2 ->
0 rpm 0.0 % 0 1 0 18.4 °C
In addition check the idling speed switch display in display zone 3. The middle position must show 1. Display: 0 1 0
Depress accelerator pedal slowly until fully down, and observe display zones 2 and 3.
Read measured value block 2 ->
0 rpm 100.0 % 0 0 0 18.4 °C
Display zone 2: The accelerator pedal position value must increase continuously. Specification at full throttle position: 100 %
Display zone 3: The middle position must change to 0. Display: 0 0 0
Note
The kickdown switch pressure point must be distinctly noticeable before the full throttle stop.
Press the
→
button.
Press buttons
0
and
6
for function
“End data transfer”
and confirm entry with
Q
button.
Switch off ignition.
End specification value not achieved:
Renew
accelerator position sender
G79
Item
Read fault memory.
Display does not change or is erratic:
Check accelerator position sender wiring as follows:
Remove wiper arms and cowl panel:
Rep. Gr.
92
Connect
121-pin adapter cable
V.A.G 1598/31
to control unit wiring harness. The engine control unit remains disconnected.
Remove cover in footwell (driver side).
Disconnect 6-pin connector for
accelerator position sender
G79
.
Check wiring between test box and connector for open circuit referring to current flow diagram.
Contact 1 + socket 63
Contact 2 + socket 12
Contact 3 + socket 50
Contact 4 + socket 69
Contact 5 + socket 70
Contact 6 + socket 51
Wire resistance: max. 1.5 Ω.
Also check wiring for short to one another, short to earth and short to battery positive.
Specification: ∞ Ω.
If no fault in lines is detected:
Renew
accelerator position sender
G79
Item
.
Read fault memory.