P2601 troubleshooting

Friends,

I recently bought a 07 Prius with 84k miles. Previous owner disconnected the battery to hide check engine light. I bought it and it is a P2601.

First I checked the fuse and relay, which were good. I ordered the CHS pump. Then I suspected wiring issue.

Took the bumper and driver side headlight off to access the pump. Took the connector off to test it.

Now, I am a new DIYer and I have no idea what I'm doing so decided to do trial-and-error.

The pump connector has two wires, one black and one white. With 2V voltmeter setting on my multimeter, white wire port reads reads -0.275V, while black wire port reads 0V. Using the same multimeter setting, headlight connectors read around -0.275V.

Using 20k ohmmeter, white wire port on the connector reads 0.75 and keeps increasing, and black reads 0. Using the same setting, both wires on both headlight connectors read around 0.75 and keeps increasing.

Am I doing this right? And what is my next move?

Also, I tried operating the CHS pump using 10amp in the pump relay. Nothing.

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Or, given that this is a grounding issue since black wires are grounding wires, can I just cut the wire and manually ground it to nearby metal object?

I will probably try it before someone answers

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Just did some more troubleshooting on the pump. I grounded ground terminal and comnected power terminal directly to 12v battery terminal and the pump doesn't run. Now I am starting to think the pump seized.

But do I also have electrical issue? I tested the relay terminal and at 12v voltmeter setting, CHS W/P only read 9v+ but increasing. Other terminal read at 12v+.

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