No power to coolant pump?

2014 BMW 528
91,000 MILES • 4 CYL • TURBO • 2WD • AUTOMATIC
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BHAMDOC1973
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I bought this car with 90,000 on it. Keeps giving a message when run for a while that its overheating. No leaks, full coolant, fan comes on. Only code is cd9010, not much info online other than it could be the pump or wiring. I removed the coolant pump connector, whether car on or off thick brown has ground. Thick red has nothing. 2 small wires have some readings, one i think was 14.3 and the other 10.2 i think those are data and signal. Where does this power wire go to? I pinched it from up where it runs and still no power.

I am almost sure the alternator wire is shared but since there are no battery or charging issues not sure.
I followed the red wire and it goes to a distribution box on rear of engine compartment on passenger side, even though its sealed I opened it and connected it back, checked the fuses all good, but the 50 amp weird looking fuse only has power on one side, not the other, not sure if this is how it is. Some people said online that the 40-amp fuse is for coolant pump, but it has power.
May 16, 2024 at 9:35 AM
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BHAMDOC1973
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Here are pics and video.
May 16, 2024 at 11:40 AM
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STRAILER
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I don't see the pics or video?
May 16, 2024 at 12:34 PM
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BHAMDOC1973
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Sorry, it uploaded and i submitted it but for some reason didn't show up before.
May 16, 2024 at 12:41 PM
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STRAILER
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Thank you, yep, that 50-amp fuse should have power all the time, I would test the red wire at the coolant pump here is a guide to help, and if it has power check the ground at the brown wire. If you have both I suggest replacing the coolant pump with a new unit.

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

Here are the wiring diagrams for the pump so you can see how the system works. Check out the images (below). Please let us know what happens.
May 17, 2024 at 9:27 AM
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BHAMDOC1973
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Hi, I indicated in my first post that the red wire at pump has no power. I am sure it is not the pump. And the brown has ground. That is why I am tracing the red one back to the fuse.
May 17, 2024 at 10:10 AM
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BHAMDOC1973
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Does the power come from the back of the 50-amp fuse or its front?
May 17, 2024 at 12:18 PM
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JACOBANDNICKOLAS
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Hi,

When you check the 50a fuse, it should have power at both sides. If it doesn't, the fuse is likely the problem. I couldn't tell in the video what you were pointing at.

Let us know.

Joe
May 19, 2024 at 6:59 PM
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BHAMDOC1973
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A new power fuse box solved it. Thanks
May 21, 2024 at 5:02 PM
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JACOBANDNICKOLAS
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Hi,

Thanks for the update. I'm glad you were able to resolve the issue.

Take care and feel free to come back in the future.

Joe
May 21, 2024 at 6:51 PM