A8L V8-4.2L (BFM) (2004)
Coolant Temperature Sensor/Switch (For Computer): Testing and Inspection
Engine Coolant Temperature (ECT) Sensor -G62-, Checking
Recommended special tools and equipment
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VAG1526 multimeter or VAG1715 multimeter
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VAG1594 connector test kit
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Wiring diagram
Test requirements
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The respective fuses of Engine Control Module (ECM) -J623- must be OK
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Parking brake must be engaged or else daylight driving lights will be switched on.
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Engine must be cold.
Function test
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Connect diagnostic tester.
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Switch ignition on.
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Under address word 33, select "Diagnostic mode 1: Checking measured values."
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Select the measuring value "PID 05: Coolant temperature".
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Check specified value of coolant temperature:
PID Diagnostic text
Specified value:
05:
Coolant temperature
approx. coolant temperature
If specified value is obtained:
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Start engine and let run at idle.
Specified value: Temperature value must rise evenly
NOTE:
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The temperature increases in increments of 1.0 degree C.
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If the engine shows problems in certain temperature ranges and if the temperature does not climb uniformly, the temperature signal is intermittent
and the sensor should be replaced.
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Engine Coolant Temperature (ECT) Sensor -G62- is a temperature-dependent resistance. If e.g. moisture in a harness connector leads to a false
sensor signal (effect is like resistance connected in parallel), this falsification can still be in a range that is not recognized by the control module.
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If a malfunction regarding Engine Coolant Temperature (ECT) Sensor is stored, control module operates with a calculated replacement value.
If no realistic indication follows:
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Disconnect connector from Engine Coolant Temperature (ECT) Sensor -G62-.
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Use adapter cables from V.A.G 1594 connector test kit to connect V.A.G 1526 portable multimeter to terminals 1 and 2 of sensor for resistance
measurement.