A8 Quattro Sedan V8-4.2L (AUX) (2001)
Engine Speed Sensor: Testing and Inspection
Engine Speed (RPM) Sensor -G28-, Checking
Engine Speed (RPM) Signal -G28-, Checking
NOTE: The engine speed sensor is a combined speed sensor and reference mark sensor.
Checking engine speed sensor
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Before carrying out the test, make sure that sensor is correctly installed and firmly seated.
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Check sensor and sensor wheel for damage and make sure they are not obstructed by metal particles.
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Thickness of spacer between sensor and transmission should be 4.5 mm.
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Disconnect harness connector for engine speed sensor (grey connector).
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Connect multimeter (Fluke 83 or equivalent) (resistance test range) to terminals 2 and 3 on connector for engine speed sensor using test lead from
VAG1594 connector test kit.
Specification: approx. 450 to 1000 ohm
NOTE:
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The resistance value for the engine speed sensor is based on a temperature of 20 °C
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The resistance increases as the temperature rises.
If the specification is not attained:
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Replace engine speed sensor.
If the specification is attained:
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Connect multimeter (Fluke 83 or equivalent) (resistance test range) between terminals 2 and 1 (Ground (GND)) and between terminals 3 and 1
(Ground (GND)).
Specification: R Ohms (infinite Ohms/open circuit) in each test
If the specification is not attained:
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Replace engine speed sensor. If the specification is attained:
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Check wiring between sensor connector and engine control module as follows:
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Connect VAG1598/31 test box to wiring harness for engine control module. Do not connect to the engine control module itself. Refer to "Scan
Tool Testing/Scan Tool Connecting and Initial Checks/Connecting VAG1598/31 Test Box" See: Powertrain Management/Computers and Control
Systems/Testing and Inspection