Checking fuel pump control unit J538 - vehicles with 4-cylinder TFSI engine — AUDI

Checking
fuel pump control unit
J538
- vehicles with 4-cylinder TFSI engine
Special tools and workshop equipment required
Hand-held multimeter
V.A.G 1526C
Auxiliary measuring set
V.A.G 1594C
Adapter cable
V.A.G 1598/39
Test box
V.A.G 1598/42
Procedure
Battery voltage at least 12.5 V.
Fuse in fuse holder
S228
(position 28) OK.
Ignition off.
Checking voltage supply for fuel pump (from
fuel pump control unit
J538
)
Saloon:
Detach trim in luggage compartment.
If necessary, fold forward right backrest of rear seat bench.
Avant:
Remove left-side section of backrest (1/3 section)
Rep. gr.
72
.
Remove left-side trim in luggage compartment and anti-soiling tray
Rep. gr.
70
.
All vehicles:
Unscrew cover for flange
arrows
.
Push back protective sleeve.
Connect
hand-held multimeter
V.A.G 1526C
(voltage test range) with probes and plug-in adapters from
adapter set
V.A.G 1594C
between contacts
1
and
4
, as shown in illustration; the connector remains in place.
Note
The connector contacts are numbered accordingly on the back of the connector.
Start engine.
Specification when starting and at idling speed: approx. 4 ... 5.7 V.
Press accelerator pedal quickly to the floor and release again (short throttle burst).
Specification: The voltage value should first increase slightly, then drop and eventually rise to the previous reading.
If display differs from specification described above:
Check voltage supply and activation of fuel pump control unit
J538
.
Checking voltage supply for
fuel pump control unit
J538
Unplug electrical connector
arrow
on
fuel pump control unit
J538
.
Connect multimeter between contacts
3
and
4
of connector to measure voltage.
Switch on ignition.
Specification: approx. battery voltage
If specification is not obtained:
Eliminate open circuit in wiring (refer to current flow diagram).
Checking activation of
fuel pump control unit
J538
Connect multimeter for voltage measurement with measuring probes and plug-in adapters from
auxiliary measuring set
V.A.G 1594C
between contacts
4
and
5
, as shown in illustration; the electrical connector remains in place.
Note
The connector contacts are numbered accordingly on the back of the connector.
Start engine.
Specification when starting and at idling speed: approx. 5.0 V.
Press accelerator pedal quickly to the floor and release again (short throttle burst).
Specification: The voltage value should first increase slightly, then drop and eventually rise to the previous reading.
If display differs from specification described above:
Switch off ignition.
Connect the
test box
V.A.G 1598/42
to wiring harness with adapter lead
V.A.G 1598/39-1
or adapter lead
V.A.G 1598/39-2
. Do not connect engine control unit. Connect earth clip of test box to negative terminal of battery
Rep. gr.
24
.
Caution
To prevent damage to electronic components, select appropriate measuring range before connecting measuring leads and observe test requirements.
Check for open circuit and short to positive or earth in the following wiring:
Connector
Contact
V.A.G 1598/42
Socket
5
B 27
Repair open circuit or short circuit in wiring (refer to current flow diagram).
If no fault is found:
Renew
fuel pump control unit
J538
.