Checking air mass meter G70 — VW

Checking
air mass meter
G70
Engine codes AGR, AHF, ALH
The air mass meter signal is used by the control unit to calculate the quantity injected and to control the required exhaust gas recirculation. The smaller the signal from
air mass meter
G70
the smaller the quantity of fuel injected.
Special tools and workshop equipment required
Fault reader
V.A.G 1551
or
vehicle system tester
V.A.G 1552
with
diagnosis cable
V.A.G 1551/3
Adapter
V.A.G 1598/22
Hand multimeter
V.A.G 1526C
or
multimeter
V.A.G 1715
Adapter set
V.A.G 1594C
Current flow diagram
Test procedure
Connect
fault reader
V.A.G 1551
or
vehicle system tester
V.A.G 1552
and select control unit for engine electronics with
“address word 01”
. Engine must be idling. (Connect fault reader and select engine electronics control unit
Chapter
.)
WARNING
Secure fault reader to rear seat and operate from this position.
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 keys
0
,
1
and
0
for
“Display group number 10”
and confirm entry with
Q
key.
Observe display in display zone 1.
Specification: 230...370 mg/stroke
Read measured value block 10 ->
309 mg/H 1027 mbar 1011 mbar 0.0 %
If the specification is not reached:
Check exhaust gas recirculation
4-cyl. diesel engine, mechanics
Rep. Gr.
26
Checking exhaust gas recirculation system
If the specification is attained:
Accelerate vehicle in 3rd gear from approx. 1500 rpm using full throttle.
At approx. 3000 rpm, press
PRINT
button on
fault reader
V.A.G 1551
.
Specification in display zone 4: 100 % (accelerator pedal position)
Read measured value block 10 ->
830 mg/H 1027 mbar 1850 mbar 100 %
If the specification is not reached:
Repeat test and accelerate vehicle at full throttle.
Specification in display zone 1: above 800 mg/stroke (air mass drawn in).
Read measured value block 10 ->
830 mg/H 1027 mbar 1850 mbar 100 %
If the specification is not reached:
Renew
air mass meter
G70
.
If a constant 550 mg/H (predetermined replacement value) is displayed in display zone 1.
Press
→
button.
Press keys
0
and
6
for function
“End data transfer”
and confirm entry with
Q
key.
Switch off ignition.
Separate connector for
air mass meter
G70
Chapter
.
Switch on ignition.
Engine codes AGR, AHF
Measure voltage supply for
air mass meter
G70
between following connector contacts:
Connector on
G70
contact
Specification
3 + earth
Approx. battery voltage
3 + 5
Approx. battery voltage
1 + earth
Approx. 5 V
1 + 5
Approx. 5 V
Engine code ALH
Measure voltage supply for
air mass meter
G70
between following connector contacts:
Connector on
G70
contact
Specification
2 + earth
Approx. battery voltage
2 + 3
Approx. battery voltage
4 + earth
Approx. 5 V
4 + 3
Approx. 5 V
Continuation for all engine codes
If the specifications are not reached:
Switch off ignition.
Connect
adapter
V.A.G 1598/22
to control unit wiring harness.
Engine codes AGR, AHF
Check wiring between adapter and connector for open circuit using current flow diagram. Contact 1+socket 50 Contact 2+socket 25 Contact 3+socket 2 and 28 Contact 5+socket 1 and 27 Contact 6+socket 52
Cable resistance: max. 1.5 Ω.
Engine code ALH
Check wiring between adapter and connector for open circuit using current flow diagram. Contact 2+socket 2 and 28 contact 3+socket 4 contact 4+socket 50 contact 5+socket 52.
Cable resistance: max. 1.5 Ω.
Continuation for all engine codes
Also check wiring for short to one another, short to vehicle earth and short to battery positive.
Specification: ∞ Ω.
If no fault in lines is detected:
Renew
diesel direct injection system control unit
J248
Chapter