Checking intake manifold pressure sender G71 and intake manifold temperature sender G72 — VW

Checking
intake manifold pressure sender
G71
and
intake manifold temperature sender
G72
Altitude sender
F96
is located in
diesel direct injection system control unit
J248
. The
intake manifold pressure sender
G71
is a separate component and is located together with
intake manifold temperature sender
G72
in a common housing
Chapter
.
Special tools and workshop equipment required
Fault reader
V.A.G 1551
with
LT diagnostic cable
V.A.G 1551/5B
Turbocharger tester
V.A.G 1397A
Adapter
V.A.G 1598/30
Hand multimeter
V.A.G 1526C
or
multimeter
V.A.G 1715
Adapter set
V.A.G 1594C
Current flow diagram
Test sequence
Connect
fault reader
V.A.G 1551
and select engine electronics control unit with
“address word 01”
. The ignition must be switched on for this purpose. (Connect fault reader and select engine electronics control unit
Chapter
.)
Indicated on display:
Rapid data transfer HELP
Select function XX
Press buttons
0
and
8
for function
“Read measured value block”
and confirm entry with
Q
button.
Indicated on display:
Read measured value block HELP
Input display group number XXX
Press buttons
0
,
1
and
0
for
“Display group number 10”
and confirm entry with
Q
button.
Compare display in display zone 2 (
altitude sender
F96
), display zone 3 (
intake manifold pressure sender
G71
) and display on
turbocharger tester
V.A.G 1397A
with one another. Specification: Pressures must be very similar (tolerance ± 50 mbar).
Read measured value block 10 ->
0 mg/H 1027 mbar 1013 mbar 0.0 %
Note
The
turbocharger tester
V.A.G 1397A
is required to provide an independent figure for comparison. The
turbocharger tester
V.A.G 1397A
must be set to measuring range I (absolute pressure). A barometer can be used instead.
Value in display zone 2 deviates:
Press the
→
button.
Press buttons
0
and
6
for function
“End data transfer”
and confirm entry with
Q
button.
Switch off ignition.
Renew
diesel direct injection system control unit
J248
Chapter
.
Value in display zone 3 deviates:
Press the
→
button.
Press buttons
0
and
6
for function
“End data transfer”
and confirm entry with
Q
button.
Start engine and select function 08
“Read measured value block”
again.
Press buttons
0
,
1
and
0
for
“Display group number 10”
and confirm entry with
Q
button.
Disconnect connector for intake manifold pressure sender
Chapter
.
Observe value in display zone 3 (
intake manifold pressure sender
G71
).
It must drop briefly to approx. 200 mbar and then assume the value of the altitude sender (display zone 2).
Read measured value block 10 ->
515 mg/H 1009 mbar 1009 mbar 0.0 %
If the specification is attained:
Renew
intake manifold pressure sender
G71
with
intake manifold temperature sender
G72
.
If the specification is not attained:
Press the
→
button.
Press buttons
0
and
6
for function
“End data transfer”
and confirm entry with
Q
button.
Switch off ignition.
Connect
adapter
V.A.G 1598/30
to control unit wiring harness. The engine control unit remains disconnected.
Check cables between test box and connector for open circuit according to current flow diagram.
Contact 3 + socket 3/14
Contact 4 + socket 3/15
Wire resistance: Max. 1.5 Ω
Also check cables for short to one another, short to vehicle earth and short to battery positive. Specification: ∞ Ω
If no fault is detected in the wiring:
Renew
diesel direct injection system control unit
J248
Chapter
.