Checking voltage supply and current consumption of fuel supply pump, vehicles with 6.0 bar low pressure fuel system — VW

Checking voltage supply and current consumption of
fuel supply pump
, vehicles with 6.0 bar low pressure fuel system
Note
Applies for version A and version B.
Special tools and workshop equipment required
Pickup clamp
V.A.G 1526B/2
Hand-held multimeter
V.A.G 1526D
Test instrument adapter/DSO (5-pin)
VAS 5565
Vehicle diagnosis, testing and information system
VAS 5051B
Pressure gauge
VAS 6551
Hose adapter set
VAS 6551/5
Adapter
VAS 6551/5-1
Hose adapter
VAS 6551/5-2
Hose adapter
VAS 6551/5-3
Test prerequisites
Fuses must be OK.
The battery voltage must be at least 12 V, if necessary connect a battery charger.
All electrical consumers, e.g. lights and rear window heating, must be switched off.
Visual check of cables OK.
Checking function and voltage supply
Lower fuel tank
Chapter
.
First check that connector
1
is fitted securely, without pressing catch. The connector can cause a fault if it has not been fitted correctly.
Release connector
arrow
and pull off from flange of fuel delivery unit
1
.
Connect
test instrument adapter/DSO (5-pin)
VAS 5565
between connector and flange.
Connect
hand-held multimeter
V.A.G 1526D
to contacts
1
and
5
of adapter.
Connect
vehicle diagnostic tester
, and carry out guided function
“Check electrical fuel pump(s)”
.
Note
The fuel pump is now activated for 30 seconds.
Read voltage value on
hand-held multimeter
V.A.G 1526D
: specification = battery voltage (- 0.5 V OK).
If no voltage is present:
Check actuation of fuel pump relay and wiring for open circuit and short circuit
Vehicle diagnostic tester
.
Voltage supply OK.
Check current consumption of
fuel pump
.
Checking current draw of fuel pump
Note
The battery voltage and the diesel fuel temperature have a great influence on the current draw of the fuel pump. For this reason, measures should be taken to ensure that battery voltage is at least 12.5 V during the check.
Depending on the season, make sure that the vehicle is filled with winter diesel if necessary.
Test prerequisites
Battery voltage at least 12.5 V
Diesel fuel temperature above 10 °C
Carry out the following work:
First check that connector
arrow
is fitted securely without pressing catch. The connector can cause a fault if it has not been fitted correctly.
Release connector
arrow
and pull off from flange of fuel delivery unit.
Connect
test instrument adapter/DSO (5-pin)
VAS 5565
to connector and fuel delivery unit.
Connect pick-up clamp
A
to red terminal with lettering
“pick-up clamp”
for
test instrument adapter/DSO (5-pin)
VAS 5565
.
Note
Pickup clamp of
hand-held multimeter
V.A.G 1715
can also be connected to red terminal with lettering
“pickup clamp”
of
test instrument adapter/DSO (5-pin)
VAS 5565
.
Switch ignition on.
Connect
vehicle diagnostic tester
, and carry out guided function
“Check electrical fuel pump(s)”
.
Note
The fuel pump is now activated for 30 seconds.
Take current draw reading on
hand-held multimeter
V.A.G 1526D
. Specification: at least 8.0 amperes, no more than 14.0 amperes.
If the measured value is not within specifications:
Remove fuel delivery unit
Chapter
.
Check that the electrical lines between flange and fuel pump are connected and have continuity.
If no open circuit can be found
Renew fuel delivery unit
Chapter
.