Motronic Fuel Injection and Ignition System (6-cylinder)
Page 1 of 3
Checking fuel tank breather
Checking activated charcoal filter solenoid valve 1 -N80
Special tools and workshop equipment required
◆ V.A.G 1526 A
◆ V.A.G 1527 B
◆ V.A.G 1594 A
◆ V.A.G 1598/31
◆ VAS 5051 with VAS 5051/1
or
◆ V.A.G 1551 with V.A.G 1551/3 A
Note:
The activated charcoal filter system solenoid valve 1 is also referred to in this context as fuel tank breather
valve of ACF valve.
Testing for leaks
When there is no electrical supply, solenoid valve remains closed.
‒ Disconnect hoses from ACF valve but leave the electrical connector plugged in.
‒ Connect auxiliary hose to one connection of ACF valve.
‒ Connect vehicle diagnostic, testing and information system VAS 5051 or fault reader V.A.G 1551 and
select engine electronics control unit with "Address word" 01 => Page 01-3
For this purpose, the ignition must be switched on.
‒ Initiate final control diagnosis and actuate ACF solenoid valve -N80 =>Page 01-51.
→ Indicated on display:
Final control diagnosis
⇒
Solenoid valve 1 for activated charcoal filter -N80
◆ The valve should click...
◆ ...and should open and close
(check by blowing into the auxiliary
hose).
If the valve does not click:
‒ Checking internal resistance of ACF
valve.
If valve does not open and close properly:
‒ Replace -N80 solenoid valve for
activated charcoal filter.
Checking internal resistance
‒ Unplug connector on ACF valve.
‒ → Connect multimeter to injector to
measure resistance.
‒ Specified value: 22...30 ω
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17.04.2010
Motronic Fuel Injection and Ignition System (6-cylinder)
Page 2 of 3
If specification is not attained:
‒ Replace -N80 solenoid valve for
activated charcoal filter.
If specified value is attained:
‒ Check the voltage supply
=>Page 24-148.
Checking power supply
Test requirements:
● Fuse for ACF valve OK.
=> Current Flow Diagrams, Electrical Faultfinding and Fitting Locations binder
● Fuel pump relay OK; checking
=>Page 24-65.
Note:
The ACF valve receives its power supply
via the fuel pump relay.
‒ Unplug connector on ACF valve.
‒ → Connect voltage tester V.A.G
1527 B as follows:
Connector
Contact
1
Measure at
engine earth
‒ Operate the starter briefly (the
engine may start).
‒ The LED should illuminate.
If the LED does not illuminate:
‒ Check the wiring from contact 1 on
the connector via the fuse to the fuel
pump relay for an open circuit.
=> Current Flow Diagrams, Electrical Faultfinding and Fitting Locations binder
‒ Rectify open circuit, if necessary.
If the LED illuminates:
‒ Check actuation.
Checking actuation
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17.04.2010
Motronic Fuel Injection and Ignition System (6-cylinder)
Page 3 of 3
‒ → Connect voltage tester V.A.G
1527 B to contacts 1 (positive) and 2
of the connector.
‒ Initiate final control diagnosis and
actuate ACF solenoid valve -N80
=>Page 01-51.
‒ The LED should flash
If the LED lamp does not flash or if it
illuminates continuously:
‒ Connect test box V.A.G 1598/31 to
wiring harness for engine control
unit; do not connect the engine
control unit => Page 24-17.
‒ → Check for open circuit and short to
positive or earth in the following
wiring connection:
Connector
Contact
2
Test box V.A.G
1598/31
Socket
64
‒ Rectify any open/short circuit as
necessary.
If the wiring is OK:
‒ Replace engine control unit => Page
24-23.
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17.04.2010