Does anyone have definitive information on how to test the electric water pump, or how long/when it should run. Mine is totally random apart from always running for a while when the battery is connected
Deleted my previous post because it was wrong. To test the fan controller output to the pump you must either have a working pump or a fairly high load test tamp. Using a normal multimeter will not work! Why? I took my fan controller apart after testing with a Multimeter as I though I had a dead controller (I didn't), not a fun job scraping the silicone out. Upon opening, its a fairly simple device, two big relays, control electronics and a solid-state relay. The latter, a ST VN02NSP, is interesting. Its a 6 amp maximum rated solid-state relay with, "No Load Diagnostic output". I.e. Until load current is at least 70mA it will not supply full power, hence why you cannot test this with a multimeter. The pump test procedure from VW is: Turn ignition on, Turn ignition off, immediately check if pump is running From SSP: The pump should run while the ignition is one and for a maximum of 10 minutes when the ignition is switched off. It is designed to prevent overheating, hotspots when the ignition is off and increase heater performance at low engine RPM.
Cheers! Exactly, I suspect this load sensing thing has caused a lot of confusion. Along with the fact when the brushes wear out, the action of unplugging/plugging in the pump can make them start working again. Not really sure why VW went to the effort of implement the load sense thing. I guess it must be something internal where the cooling profile with fan is more aggressive if the pump fails, or a carryover from Phaeton where the pump is actually used with the preheater
