Temperature Gauge: Testing and Inspection

Engine Coolant Temperature (ECT) gauge, checking




Electronic thermoswitch connections
+ voltage supply, terminal 15a
C to overheat warning lamp
R to A/C control unit
T to coolant temperature gauge

The thermal switch -F76- is located on the coolant line behind the right-side cylinder head.


- Disconnect thermal switch connector.
- Set digital multimeter (Fluke 83 or equivalent) to voltage measuring range.




- Connect multimeter between thermal switch connector terminal T and Ground (GND), using VW 1594 connector test kit.
- Switch ignition on.
Specification: 9.8-10.4 volts
- Switch ignition off.

If voltage is not as specified:
- Check wiring for open circuit according to wiring diagram, and repair as necessary.
- Check voltage stabilizer. Testing and Inspection




- Connect VW 1301 instrument/gauge tester between thermal switch connector terminal -T- and Ground (GND), using VW1594 connector test kit.
- Adjust VW 1301 to setting of 560.
- Switch ignition on.




Gauge needle must lie within tolerance range -A- (arrows).

- Adjust VW 1301 to setting of 58.
Gauge needle must lie within tolerance range -B- (arrows).

If specification is not met:
- Replace Engine Coolant Temperature (ECT) gauge.

If voltage is OK, but the ECT gauge reads incorrectly:
- Check Ground (GND) connection to ECT thermal switch.
- Replace electronic ECT thermal switch -F76-.