I tested the water pump's electrical input harness with a multimeter:
legend:
~pin1- thick red positive wire
~pin2- smaller wire (forgot color)
~pin3- another smaller wire
~pin4- thick black negative ground wire
**note the pins are labeled on the harness from 1 to 4.
When car was off: (i tested from each pin to pin4, the ground)
~pin1- 12V
~pin2- 0V
~pin3- 0V
When coolant bleed procedure was in progress (pump running):
~pin1- 12-13V (or a little over that)
~pin2- 12V
~pin3- 7.5V (rounded value)
My water pump when plugged in and running the bleeding procedure did not make the pump running noise which should sound like a small dishwasher going off. instead it made like practically no noise, except for an intermittent buzzing noise. I got the yellow overheat indicator then the red indicator. But before I bought a replacement water pump I wanted to rule out the fuse/electrical harness/distribution block as being the main problem.
I think that this is an easier way to check the electrical aspect of the system. Getting to the F07 or F09 fuses in the e-box (engine bay fuse box) is very difficult for me. I just gave up lol. and as for the distribution block, i took a look, wiggled some of the wires, gave it a couple good hits just in case
then walked away. too complicated to check. I hope this helps.