Fuel consumption signal, checking

Special tools and equipment 

• Multi meter V.A.G 1526
• Test box V.A.G 1598 with adapter V.A.G 1598/25
• Measuring aid set V.A.G 1594
• Test box for each individual engine control unit

• Start the engine and test drive.
• Observe consumption display in the instrument cluster.

Indicated on display:

1. continuously 0.0 L/100 km 

   eventually the signal wire is shorted to battery minus.

   • Switch ignition off.
   • Connect the individual Test box to engine control unit t.

     See appropriate Multiport Fuel Injection (MFI) article in Engine Performance.

   • Instrument cluster removal (See INSTRUMENT CLUSTER, REMOVING AND INSTALLING  ): disconnect the blue 32-pin connector from the instrument cluster.
   • Connect the test box V.A.G 1598 with the adapter V.A.G 1598/25 to the 32-pin connector.
   • Use the multi meter V.A.G 1526 and connect (+) test lead on the test box V.A.G 1598/25 sleeve 25.
   • Connect the (-) Test lead of the individual test box of the engine control unit and the appropriate consumption signal bushing of the engine control unit.
   • Perform resistance measurement.

     Specification: display < 2 Ohm

   • Connect the multi meter V.A.G 1526 (+) Test lead to the individual test box engine control unit.
   • Connect the (-) Test lead to battery positive and negative.
   • Perform resistance measurement.

     Specification: display > 9 M Ohm

   • If the specification is met, the wire connection is OK.
2. continuously 51 L/100 km 

   See possible break in signal wire.

   • Switch ignition off.
   • Connect the test box to the engine control unit.

     See appropriate Multiport Fuel Injection (MFI) article in Engine Performance.

   • Instrument cluster removal. See INSTRUMENT CLUSTER, REMOVING AND INSTALLING  . Disconnect the blue 32-pin connector from the instrument cluster.
   • Connect the test box V.A.G 1598 with the adapter V.A.G 1598/25 to the 32-pin connector.
   • Connect the multi meter V.A.G 1526 (+) Test lead of the test box V.A.G 1598/25 to bushing 25
   • Connect the (-) Test lead of the individual test box of the engine control unit and the appropriate consumption signal bushing of the engine control unit.
   • Perform resistance measurement.

   Specification: display 2 Ohm

   • Connect the multi meter V.A.G 1526 (+) Test lead to the individual test box engine control unit.
   • Connect the (-) Test lead to battery positive and negative.
   • Perform resistance measurement.

   Specification: display > 9 M Ohm

   • If the specification is met, the wire connection is OK.
3. The consumption display has an unreal or varying value 

The consumption display is different than the actual fuel consumption.

• Perform the adjustment of the consumption display. See ADAPTATION OF FUEL CONSUMPTION DISPLAY .