how many volts normally go to the water pump?

[Joseg0715]

My water pump isn't spinning so I took off the under tray and put the car in coolant bleeding mode. After I did that I unplugged the water pump and tested the voltage and got a range of 4v to 9v. Is that enough to make the water pump spin or is my pump bad?

Also has anyone tried the mishimoto water pump? Its from a known brand and is cheaper than the pierburg on FCP Euro.

[iminhell1]

It's PWM controlled. So the voltage will change. It's the waveform that you need to look at, which you'll need a scope for. At the point of buying the correct tools to check you've come to the cost of just replacing it.

[JonOhh]

The water pump recieves 12v across pins one and four in the connector. I can't remember where/what controls the water pump relay, but of course during bleeding or any DME on state, you should see 12v across those pins at all time.

Pins two and three are used for control of the pump. Pin 2 is a PWM input, 3 is a BSD communication line. The pumps internal controller translates PWM input into a few different modes, as well as a speed target. BSD is used for status and error reporting. I'm not entirely sure what the DME uses to control the pump primarily (bsd comm vs PWM), but the pump accepts either.

First ensure 12v, especially grounds. It should not be significantly different than what you can read across the B+ and GND terminals under the hood.

If you get 12v and the pump is mechanically okay but still refuses to run I'd begin looking at INPA pump diagnostics tab, and diagnosing wiring issues.

You can also manually control the pump without the DME by sending a 1 second 12v pulse to pin 2, it should wake up the controller and run full speed. After removing the 12v on pin 3 it'll drop down to medium speed (or shut off depending on revision) until pins 1 & 4 stop receiving 12v.