Jumping CHS Water Pump with multimeter

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Sean I., Jan 27, 2020.

  1. Sean I.

    Sean I. New Member

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    I'm trying to jump CHS water pump using my multimeter but it's not working. Here's a little background:

    This is my first Prius (2007 89K miles) and I've had it for 6 months.

    50 miles after purchase from private owner, I had P2601 code pop and replaced the CHS WP with a generic pump from Amazon. Code came back after 50 miles. I went to the dealer and they said pump seems to be running but there is not movement of coolant and recommended replacing the pump with genuine Toyota part.

    I ordered the part myself and replaced it myself. CEL didn't come back.

    2 weeks ago, a 1000 miles later, CEL comes and with P1116 code. According to the manual, there is either clog in the coolant system or CHS sensor is malfunctioning.

    I thought I might have introduced air bubbles into coolant system when I replaced the pump so I found youtube video on how to replace and bleed coolant. The guy in the video ran the pump manually using his multimeter in order to circulate the new coolant.

    I tried it on my car with my multimeter but nothing. I used the following setting and applied it to pin 3 and 5 of the relay socket, the horizontal pins:

    upload_2020-1-27_15-31-38.png

    What am I doing wrong? The pump does run when engine is running, however I feel like it's running rather weak, compared to the pump I saw in the guy's youtube video. So I'm also uploading my car running:



    I was going to check the sensor and replace and bleed the coolant at the same time, but I wanted to make sure I can run the pump with multimeter before I even start.

    Any help is appreciated.
     
  2. Mendel Leisk

    Mendel Leisk 'Orrible Oracle

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    CHS = Coolant Heat Storage I think?
     
  3. Sean I.

    Sean I. New Member

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  4. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Pins 3 and 5 are the relay switched terminals and are correct. Use a paper clip to jump the terminals and see if the pump activates. If it does, and if you can't get the pump to run using the multimeter, then maybe the multimeter fuse which protects against excessive current has blown.
     
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  5. Sean I.

    Sean I. New Member

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    Patrick

    thank you for your reply.

    So I just bought another multimeter (it was cheaper than replacing the fuses) and gave it another try to jump the pump. Nothing.

    Then I tested the relay terminal for 20V DC setting. Multimeter showed 5.8V but slowing increasing. Other terminals showed steady 12.81V. So I think this is a problem. What would you suggest?
     
  6. Priuslover09

    Priuslover09 Junior Member

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    I don’t think you can jump a water pipe. I could be incorrect about this.
     
  7. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Connect the multimeter negative test lead to body ground, and the positive test lead to pin 3 of the CHS W/P relay socket. You should measure ~12.8V (assuming the 12V battery is fully charged.)

    If you do not, check the 10A CHS W/P fuse. Remove the fuse and measure voltage at the fuse socket. One pin should show ~12.8V and the other pin will show 0V since the fuse is not installed.
     
  8. Sean I.

    Sean I. New Member

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    Patrick,

    I'm getting 0V on the relay socket... what's my next move? I'm thinking take the relay box off and fix the connection?

    Perhaps I can "hotwire" the pump and flush the coolant while doing it?
     
  9. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Your next move is to check the fuse and if it is good, see if you can measure 12V at one terminal of the fuse socket.
     
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