5000S Quattro Sedan L5-2309cc 2.3L SOHC (NF) (1988)
Differential Pressure Regulator: Testing and Inspection
(Fault code 4341)
NOTE: The regulator and its operation is the same as used on CIS-E fuel injection. The operating range during closed loop (oxygen sensor regulation)
is different. The operating range is +10mA to -10mA. The nominal CO adjusting point is 0mA. This insures better engine operation if an electrical
failure should occur, by providing a fuel mixture which is in the range of the nominal setting.
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ignition in OFF position
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connect US 1119 multimeter to differential pressure regulator with adapter VW 1315 A/1. Set meter to 200mA DC scale.
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insert spare fuse in top of fuel pump relay
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turn ignition on, remove fuse after 4 seconds
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indicator light displays 4341
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close full throttle switch
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differential pressure regulator current switches to 10mA (is 100mA with full throttle switch open)
If NO
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continue checking
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disconnect harness connector from differential pressure regulator
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connect multimeter US 1119 between terminal 2 of harness connector and engine ground