Checking measuring and auxiliary devices (VW Lt 2d)

1. Disconnect the 2-pin connector 2 from the coolant circulation pump thermal switch while the engine is running 1 (figure 3.37). Connect pins 1 and 2 of connector 2 using a wire. The coolant circulation pump should start working while the engine is running.



2. If the coolant circulation pump does not work while the engine is running, disconnect the 2-pin connector from the pump and connect the VAG 1527 diode tester to the disconnected connector using auxiliary wires (figure 3.38). The light should come on.





3. If the light comes on, replace the coolant circulation pump while the engine is running. If the light does not come on, check the power wiring and correct the problem.

Checking the resistance of the thermal switch

4. Connect the VAG 1526 A hand-held tester or the VAG 1715 multimeter to the contacts of thermal switch 1 to measure the resistance (figure 3.39). Setting values: below 103°C - ∞ Ohm, above 104°C - 0 Ohm.