90CS Quattro V6-2.8L (AAH) (1994)
Coolant Temperature Sensor/Switch (For Computer): Testing and Inspection
Checking Engine Coolant Temperature Sensor
NOTE:
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For functional testing of the ECT sensor, Also Refer to On Board Diagnotic, "Read Measuring Value Block" function 08, display group 001,
display field 1. See: Powertrain Management/Computers and Control Systems/Testing and Inspection
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Disconnect ECT sensor harness connector.
Engine Coolant Temperature Sensor
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Check resistance between terminals 1 and 2 of sensor. Specified values:
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At approx. 20°C coolant temperature, approx. 2.5 K(ohms)
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At approx. 80°C coolant temperature, approx. 330 ohm
If specified values are not obtained:
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Replace ECT sensor.
If specified value is obtained, check wiring from sensor to ECM as follows:
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Connect VAG 1598 test box with VAG 1598/11 adapter harness to ECM wiring harness. See: Powertrain Management/Computers and Control
Systems/Testing and Inspection/Scan Tool Testing and Procedures/Scan Tool Testing/Scan Tool Connecting and Initial Checks/Connecting VAG
1598/31 Test Box
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Adapter harness is not connected to ECM.
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Check Ground (GND) wire for continuity between ECT sensor connector terminal 2 and GND.
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Specified value: maximum 1 (ohm)
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Check signal wire for continuity between ECT sensor connector terminal 1 and test box socket 15.
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Specified value: maximum 1 (ohm)
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Check both wires for short to each other.
If specified values are not obtained:
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Repair short and/or break in wiring between ECT sensor and ECM connector -C- and/or GND.
ECT sensor
ECM connector C
connector terminal
terminal
1
15
2
Ground(GND)
If there is no short or break in wiring, and ECT sensor is OK:
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Replace ECM.