With Manufacturer's Scan Tool
Boost Pressure Control, Checking
Special tools
- VAG 1551/1552 Scan Tool using VAG 1551/3 Adapter cable
- VAG 1598/22 Test Box (MY 1999)
- VAG 1598/31 Test Box (from MY 2000)
- Fluke 83 multimeter
- VW 1594 Adapter kit
- Wiring diagram
NOTE: To check Boost pressure control it is essential to first know the actual Boost pressure value in dependent of the Boost pressure control limits.
Test requirements
- Fuse 34 OK
Test sequence
- Measure Boost pressure using VAG 1551/1552 Scan Tool during a test drive.
WARNING!
For safe operation, use a second technician to operate test equipment and take readings from back seat, during test drive.
- Make sure Wastegate Bypass Regulator valve -N75- harness connector is connected.
- Connect VAG 1551/1552 Scan Tool.
- Start engine and let idle.
- Press 0 and 1 buttons to select Address word 01: "Engine electronics"
Display will appear as shown (example only)
038906018M 1.9l R4 EDC 00AG 1813 ->
Coding 0001 WSC XXXXXX
- Press -> button.
Display will appear as shown
Rapid data transfer HELP
Select function XX
- Press 0 and 8 buttons to select Function 08: "Read measuring value block".
- Press Q button to enter input.
Display will appear as shown
Read measuring value block HELP
Input Display group number XXX
- Press 0,1 and 1 buttons to select "Display group 11"
- Press Q button to enter input.
Display will appear as shown
Read measuring value block 11 ->
840 rpm 938 mbar 978 mbar 92 %
- Accelerate vehicle in 3rd gear from about 1500 rpm under Wide Open Throttle.
- Press PRINT button on VAG 1551 at about 3000 rpm.
- Specification on VAG 1551: 1720 to 2300 mbar (Display zone 3)
Read measuring value block 11 ->
3090 rpm 1866 mbar 1917 mbar 62 %
If measured Boost pressure is too low
- Check -N75- as follows:
Wastegate bypass regulator valve -N75-, electrically checking
- Switch OFF ignition.
- Disconnect -N75- harness connector.
- Switch Fluke 83 multimeter to resistance range.
- Measure resistance between -N75- terminals using multimeter.
Specification: 14 to 20 Ohms
If specification not obtained
- Replace Wastegate Bypass regulator valve N75.
- Display the Readiness code Monitors, Trips, Drive Cycles and Readiness Codes
If DTC memory was erased
- Set the Readiness code. Monitors, Trips, Drive Cycles and Readiness Codes
Wastegate Bypass regulator valve -N75- Voltage supply, checking
- Switch OFF ignition.
- Disconnect harness connector off valve.
- Connect Fluke 83 multimeter between terminal 1 and Ground using jumper wires from VW 1594 Adapter kit.
- Switch Fluke 83 multimeter to 20 Volt range.
- Switch ON ignition.
Specification: approx. battery Voltage
If specification not obtained
- Check wiring/connections to -N75-.
- Switch OFF ignition.
- Connect VAG 1598/22 (or 1598/31) Test Box to ECM wiring harness.
- Check wiring for open circuit between Test Box and harness connector using Wiring diagram.
Up to MY 1999
- Terminal 1 + socket 28
- Terminal 2 + socket 15
From MY 2000
- Terminal 1 + socket 2
- Terminal 2 + socket 62
- Wire resistance: 1.5 Ohms maximum
- Check wires for shorting to: one another, Ground and Battery +.
- Specification: Infinity Ohms
- Correct any open/short circuit as necessary.
If no open or short circuits exist
- Replace Engine Control Module.
- Display the Readiness code. Monitors, Trips, Drive Cycles and Readiness Codes
If DTC memory was erased
- Set the Readiness code. Monitors, Trips, Drive Cycles and Readiness Codes