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Diverting fuel (for auxiliary heater) from fuel tank > < Activating and deactivating auxiliary heating/auxiliary ventilation by way of Multi Media Interface (MMI)

A4 Mk3

Diverting fuel for auxiliary heater
Diverting fuel for auxiliary heater
  Note
t  Air in the auxiliary heater fuel supply can lead to problems in auxiliary heater operation. To stop air being drawn in by the metering pump -V54- and conveyed to the auxiliary heater when the auxiliary heater is first switched on after working on the fuel tank or fuel delivery unit, the fuel diversion pipe is to be filled with fuel (bled) after working in this area → Chapter.
t  The following illustration shows the positions of the components on an Audi A5 Coupé. The layout differs slightly on the Audi A4 and Audi Q5. Unless otherwise indicated, the components are however to be removed and installed in the same manner as described for the Audi A5 Coupé.
  WARNING
Observe the applicable rules for cleanliness, take the appropriate precautions and heed the relevant safety measures when working on open fuel systems → Fuel supply system; Rep. Gr.20.
  Note
t  The fuel pipe must be flush with the underbody and routed so as to be protected against mechanical damage.
t  The fuel pipe to the auxiliary heater must be protected against heat generation which could affect operation.
t  The fuel pipe must not make contact with components which become warm or moving components.
t  There must not be any air in the fuel pipe to the auxiliary heater.
t  Vehicles with and without auxiliary heater have different fuel delivery units fitted in the fuel tank → Fuel supply system; Rep. Gr.20 and → Electronic parts catalogue.
t  The sections of the fuel pipe are to be butt-jointed to stop vapour bubbles accumulating at the connections.
   
1 - Metering pump -V54-
q   Removing and installing → Chapter
q   Checking fuel delivery rate → Chapter and → Vehicle diagnostic, testing and information systemVAS 5051/, “Guided fault-finding function”.
q   Checking actuation → Vehicle diagnostic, testing and information systemVAS 5051/, “Guided fault-finding function”.
q   Depending on the model, the vehicle may be fitted with noise insulation in the fuel pipe to the auxiliary heater in the area of the metering pump -V54- to reduce noise → Chapter.
  Note
As of Model Year 2009, a metering pump -V54- with a modified connector is being gradually introduced. Pay attention to correct assignment. If the metering pump -V54- with the plug connection fitted in Model Year 2008 is no longer available, a different connector (with the corresponding contacts from the wiring harness repair set -VAS 1978 B-) must be attached to the wiring harness. When doing so, pay attention to the correct connection assignment → Electronic parts catalogue and → Current flow diagrams, Electrical fault finding and Fitting locations
2 - Fuel delivery unit with connection for diverting fuel for the auxiliary heater
q   Removing and installing → Fuel supply system; Rep. Gr.20.
q   Diverting fuel from fuel tank → Chapter and → Fuel supply system; Rep. Gr.20.
q   Different fuel delivery units depending on vehicle model (petrol or diesel engine) → Fuel supply system; Rep. Gr.20.
q   Filling the fuel pipe to the metering pump -V54- with fuel (bleeding) → Chapter
3 - Fuel pipe
q   Routing of fuel pipe between fuel delivery unit and metering pump -V54- → Chapter.
q   Routing of fuel pipe from metering pump -V54- to auxiliary heater → Fuel supply system; Rep. Gr.20.
q   The sections of the fuel pipe are to be butt-jointed to stop vapour bubbles accumulating at the connections.
q   Filling the fuel pipe to the metering pump -V54- with fuel (bleeding) → Chapter
  Note
Depending on the vehicle model, the fuel pipe (from the metering pump -V54- to the auxiliary heater) may be provided with a constriction (restrictor in the fuel pipe hose) for noise reduction or fitted with noise insulation (gradual introduction of restrictor or noise insulation in Model Year 2008) → Chapter.
4 - Auxiliary heater
q   Different versions depending on the production period and vehicle model as well as for vehicles with petrol or diesel engine (the Audi Q5 for example is not to be fitted with an auxiliary heater with part number 8K0.xxx.xxx) → Chapter.
q   Removing and installing → Chapter
  Note
t  This auxiliary heater is installed in various vehicle models. The part number changes each time this auxiliary heater is fitted in a new vehicle model (e.g. from 8K0 xxx xxx to 8R0 xxx xxx on introduction of the Audi Q5 and subsequently to 4xx xxx xxx etc.). Attention must therefore be paid to correct assignment. Care must however also be taken to ensure that an old auxiliary heater version is never installed in a vehicle previously fitted with a newer version. For example, an Audi A4 provided at the factory with an auxiliary heater with part number 8R0 xxx xxx is not to be fitted with an auxiliary heater with part number 8K0 xxx xxx → Electronic parts catalogue.
t  As of 10.2010 auxiliary heaters with part number 4xx xxx  xxx are gradually to be introduced. Service installation of this version of the auxiliary heater is also possible in vehicles originally fitted with an auxiliary heater with part number 8R0 xxx xxx or 8K0 xxx xxx. As however there are differences between certain components of the various auxiliary heater versions (e.g. the 2-pin connector for the power supply to the auxiliary heater control unit -J364-), attention must be paid to correct assignment when replacing individual components of the auxiliary heater → Electronic parts catalogue.
t  If an auxiliary heater with part number 4xx xxx  xxx is fitted, attention must also be paid with this version to correct encoding for the vehicle concerned (different functions are stored in the control unit depending on the type of vehicle encoded) → Electronic parts catalogue and → "Guided fault-finding" function of vehicle diagnostic, testing and information system VAS 5051.

   

Diverting fuel (for auxiliary heater) from fuel tank > < Activating and deactivating auxiliary heating/auxiliary ventilation by way of Multi Media Interface (MMI)