For the Audi/VW CWA50 you don`t need a resistor. Just the correct connector/two cables plus and minus.

The BMW CWA50 is a different story. It needs a pwm signal for the the pump.

First hand experience.

PS: $40 used on ebay with connector

https://www.ebay.com/itm/2013-AUDI-A...pafeWh&vxp=mtr

Steven

Berlin Germany

 

Ok folks, in the spring I will do a complete write-up with install details. For now I will do a quick pictorial


I have 2 of the BMW CWA 50, and from my testing they do not need a PWM, just a resistor across pins 4(+) and pin 3 (pwm in), to enable the pump to full speed.


With the resistor modification that I mention above, you can use a "easer to source" connector, ford CU2Z-14S411-AYA It is a 2 wire connector for + and - feed. Instead of the bwm connector mentioned in the thread I posted above.
it also references to MOTORCRAFT WPT1309


The back electronics cover is removable on the CWA 50, this gives you access to the brushless drive circuit that runs the coils, and where the connector connects to the control board. I believe it is only 2 T10 hex screws that hold on the o-ringed back cover, it can be a bit difficult to remove, and a flat blade helps to pop it off.







Keep note of orientation of the connector, to verify which pin is (-), you can do a continuity check between the case and pin.


I soldered a 470Ω resistor across pin 3 (pwm), and pin 4(+12v) this enables the pump to full speed all the time.
You can use a higher resistance resistor if preferred. 1kΩ should work as well. @14v a 470Ω resistor keeps currents down to 50ma which is a typical max for low current communications if a fault were to occur.






A quick test in a bucket of water shows the pump pulling 4.6a ~ 68w @14v, which indicates the pump is at 100% speed.

 

I just want to update that now current "MOTORCRAFT WPT1309" connectors have 4 wires instead of the 2, so you can now install the resistor externally to the pump, and don't need to open up the pump back.


I ordered some spares, and can confirm.