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Correct voltage to fuel pump relay Gen 1

Discussion in 'Generation 1 Prius Discussion' started by WadeLovell, Nov 9, 2017.

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  1. WadeLovell

    WadeLovell Junior Member

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    1) I’m getting 1.1V to the activation circuit of the fuel pump relay. Would someone with the electrical manual let me know if that is correct? The fuel pump relay isn’t activating. I’ve jumped across the relay to start the car (successfully) and I’m picking up a New relay this afternoon. I already replaced the ECU this month with the newest generation since I was putting in a new I.C.E. from a donor car with 56,000 miles on it.

    2) Will it damage anything if I drive to the auto parts store with the relay jumped (~5 miles through construction)?
     
    #1 WadeLovell, Nov 9, 2017
  2. ChapmanF

    ChapmanF Senior Member

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    Are you talking about the "EFI RELAY" or the "CIRCUIT OPENING RELAY"? Both must close for the pump to run.

    The EFI RELAY coil has a permanent ground, and is controlled by switched +B from the ECM (circuit MREL). 9 to 14 volts is the spec on page 75, any time the key is IG ON.

    The circuit opening relay coil gets its +B from the EFI relay (whenever that is closed), and is controlled by the ECM pulling the other side (circuit FC) to ground. So FC should also be around 9 to 14 when the engine is stopped, but 0 to 3 when the engine is running.

    How are you measuring?

    Just to keep you on your toes, the wire color is the same (green with red stripe) for both the MREL and FC circuits. Thanks, Toyota!

    -Chap
     
    #2 ChapmanF, Nov 9, 2017
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  3. WadeLovell

    WadeLovell Junior Member

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    Thank you Chap!
    I appreciate your timely and informed reply. Since I had alerts set up, I saw your response immediately but had difficulty replying on my mobile phone. The circuit opening relay coil was getting 1.1V with the engine running. I could not get the relay to activate with an external power supply dialed in at 1, 2, or 3 volts so I replaced it. Miraculously, that turned my driveway ornament back into a fully functioning Prius. Now I have to move the new ECU from its temporary position sitting on the glove box.
    Great heads up on wire color!
    Cheers,
    Wade
     
    #3 WadeLovell, Nov 12, 2017
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