Coolant Temperature Sensor Testing and Inspection for Engine Code AAZ (1997 Passat Wagon)
Coolant Temperature Sensor/Switch (For Computer): Testing and Inspection
Engine Code 1Z
Special Tools, Testers And Auxiliary Items:
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VAG 1551/1552 Scan Tool with VAG 1551/3 adaptor cable
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Test Box VAG 1598/18
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Fluke 83 multimeter (or equivalent)
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VW 1594 adaptor kit
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Wiring diagram
Test Sequence:
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Connect VAG 1551/1552 Scan Tool
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Start engine and let idle
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Press 0 and 1 buttons to select address word 01 "engine electronics"
Display will appear as shown:
Rapid data transfer HELP
select function XX
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Press 0 and 8 buttons to select Function 08 "Read measuring value block"
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Press Q button to enter input
Display will appear as shown:
Read measuring value block HELP
Input display group number XXX
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Press 0, 0 and 7 buttons to select display group number 7
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Press Q button to enter input
Display will appear as shown:
Read measuring value block 7 ->
15.4°C 15.9°C 16.7°C
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Observe ECT value in display zone 4
value must increase uniformly and without interruption
NOTE: If the ECT sensor malfunctions, the fuel temperature sensor values are substituted to provide a backup.
If an unreasonable value appears in display zone 4 or the fuel temperature has been supplied as a substitute; check the ECT sensor and wiring
connections to sensor as follows:
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Press -> button
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Press 0 and 6 buttons to select Function 06 end data transfer
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Press Q button to enter input
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Switch OFF ignition
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Disconnect ECT sensor harness connector from ECT sensor -1-
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Measure resistance between sensor terminals 1 + 3