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Test step "3” > < Test step "1”

A4 Mk2

Test step “2”
Test step “2”
Connection from auxiliary heater to metering pump -V54- and to heater coolant shut-off valve -N279-
   
Vehicle diagnostic, testing and information system -VAS 5051A-, measurement mode: Multimeter, resistance measurement (0...100 Ω)
Test stepConnection to connector “A” → ChapterChecking of
l  Test conditions
–  Additional operations
SpecificationMeasures to be taken if reading does not match specification
2.1Contact “6”
and
contact “10”		Wiring to metering pump -V54-
l  Ignition off
–  Greater than 6 and less than 20 Ω (ohms)
–  Use current flow diagram to check and repair wiring
–  Replace metering pump -V54-
2.2Contact “3”
and
contact “10”		Wiring to heater coolant shut-off valve -N279-
l  Ignition off
–  Greater than 10 and less than 30 Ω (ohms)
–  Use current flow diagram to check and repair wiring
–  Replace heater coolant shut-off valve -N279-

  Note
t  Internal resistance of metering pump -V54- = 4.1 Ω+/-0.2 Ω
t  Internal resistance of heater coolant shut-off valve -N279- = 16 Ω+/-4 Ω
t  Resistances of less than 20 Ω can no longer be measured with the required accuracy using workshop equipment. The internal resistance test can therefore only be used to detect major component or wiring damage.
t  If connector -A- contact “3” (to heater coolant shut-off valve -N279-) is supplied with a voltage of 12 V DC, the current flow is less than 2 A (amps) and the shut-off valve switches to the small coolant circuit (with the engine running, coolant then no longer flows to the air conditioner/heater heat exchanger).
t  Contact “3” in connector -A- may also be assigned on vehicles with no heater coolant shut-off valve -N279-. → Current flow diagrams, Electrical fault finding and Fitting locations
t  At the start of production, vehicles with 4-cyl. engine were fitted with the heater coolant shut-off valve -N279-. However, in view of the fact that cold starting problems may be encountered with these engines at very low ambient temperatures following auxiliary heating operation with a small coolant circuit (engine is only slightly pre-heated), the auxiliary heater control unit -J364- is to be encoded such that the heater coolant shut-off valve -N279- is not actuated.
t  On vehicles with 4-cyl. engine, the heater coolant shut-off valve -N279- is not actuated at present. Vehicles manufactured up to Model Year 2004 may be fitted with a shut-off valve, but this is not actuated (the auxiliary heater control unit -J364- must be encoded accordingly).
t  At the start of production (up to Model Year 2004), vehicles with 4-cyl. engine were fitted with the heater coolant shut-off valve -N279-. However, in view of the fact that cold starting problems may be encountered with these engines at very low ambient temperatures following auxiliary heating operation with a small coolant circuit (engine is only slightly pre-heated), the auxiliary heater control unit -J364- is to be encoded such that the heater coolant shut-off valve -N279- is not actuated.
t  For vehicles with no heater coolant shut-off valve -N279- or vehicles with 4-cyl. engine on which the heater coolant shut-off valve -N279- is not actuated, corresponding adaption of the control unit in dash panel insert -J285- is required (“Engine pre-heating” function must not be displayed).
   

Test step "3” > < Test step "1”