Checking the thermal switch of the auxiliary pump
Turn off the engine and ignition of the vehicle Transporter T4 . The pump power on/off delay relay is only active for 10 minutes after the ignition is turned off, the test must be performed during this time. Disconnect connector A (see Fig. 242). Short the pins (1) and (2) of the harness connector with the prepared piece of wire.
Rice. 242 Checking the operation of the auxiliary pump
For engines with an additional pump, the pump should start audibly, for engines without it, the radiator fan should work.
If the pump or electric fan does not work, then it is necessary to find an open in the electrical wiring or replace the corresponding relay or fuse.
Check of resistance of a thermoswitch
Disconnect a socket And (see fig. 242).
Short-circuit the contacts (1) and (2) of the harness with a wire. For motors without an auxiliary pump, the fan should turn on, for models with a pump, the pump should turn on.
Connect an ohmmeter to contacts (1) and (2) of the thermal switch (B). Nominal value of resistance:
at temperatures below + 103ºС - infinity;
at temperatures above +104ºС - 0 Ohm.
If the resistance value obtained does not correspond to the nominal value, the thermal switch must be replaced.
Replacing thermostat T4 . cooling VR6 .