AUDI A4 1998 B5 / 1.G ATQ Engine Tank Ventilation Checking Workshop Manual

24-128


Tank ventilation, checking Evaporative Emission (EVAP) canister
purge regulator valve -N80-, checking

Special Tools and Equipment

VAG1526A
VAG1527B
VAG1594A
VAG1598/31
VAS5051 with VAG5051/1
- or
VAG1551 with VAG1551/3B
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24-129

Note:
The Evaporative Emission (EVAP) canister purge
regulator valve is also called the Tank Ventilation
Valve (TVV) and is sometimes referred to as the
EVAP valve.

Checking for proper seal
Solenoid valve is closed when no voltage is
present.

- Disconnect hoses from EVAP valve; harness
connector remains connected.

- Attach assisting hose to one connection of
EVAP valve.

- Connect VAS5051 tester or VAG1551 scan tool
and select the control module for engine
electronics using "address word" 01 Page 01
-
9 .

Ignition must remain switched on for this.

- Initiate output DTM and activate Evaporative
Emission (EVAP) canister purge regulator valve
-N80- Page 01
-56
.
Output Diagnostic Test Mode

Indicated on display:
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EVAP canister pur
ge re
gulator valve -N80
Valve must click...
...and must open and close (can be tested by blowing into assisting
hose).
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24-130
If valve does not click:

- Check internal resistance of EVAP valve.
If valve does not open and close properly:

- Replace Evaporative Emission (EVAP) canister
purge regulator valve -N80-.

Checking internal resistance

- Disconnect connector at EVAP valve.

If specified value is not obtained:
If specified value is obtained: - Connect multimeter at valve for resistance measurement.

Specification: 22 to 30
- Replace Evaporative Emission (EVAP) canister purge regulator valve -
N80-.
- Check voltage supply Page 24
-131
.
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Checking voltage supply

Test requirements:

Fuse for the EVAP valve OK.

Electrical Wiring Diagrams, Troubleshooting &
Component Locations binder

Fuel Pump (FP) OK, checking Page 24
-
49
.

Note:
Voltage is supplied to the EVAP valve via the
Fuel Pump (FP) relay.

- Disconnect connector at EVAP valve.

- Connect VAG1527B voltage tester as follows:Harness connector
Terminal
Measure to
1 Engine Ground (GND)
- Operate starter briefly (engine can also start).

LED must light up.
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24-132
If LED does not light up:

- Check wire connection from terminal 1 to Fuel
Pump (FP) relay via fuse for open circuit.

Electrical Wiring Diagrams, Troubleshooting &
Component Locations binder
- Repair open circuit if necessary.
If LED lights up:

- Checking activation.

Checking activation

- Connect VAG1527B voltage tester to connector terminals 1 (B+) and 2.
- Initiate output DTM and activate Evaporative Emission (EVAP) canister
purge regulator valve -N80- Page 01
-56
.

LED must blink.
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24-133
If LED does not blink or if it remains constantly
lit:

- Connect VAG1598/31 test box at wiring harness
to ECM, do not connect ECM Page 24
-17
.

If wire connection is OK: - Check the following wire connection for open circuit and short circuit to
Ground (GND) and B+: Harness connector
Terminal
VAG1598/31 test box
Socket
2 64
- Repair open circuit or short circuit if necessary.
- Replace Engine Control Module (ECM) Page 24
-21
.
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