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2005 Prius wiring diagram discrepancy

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by ScottFrmGeorgia, May 20, 2009.

  1. ScottFrmGeorgia

    ScottFrmGeorgia Scott the Taxi Driver

    Joined:
    Mar 9, 2008
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    Location:
    Atlanta, GA
    Vehicle:
    2005 Prius
    I have two wiring diagrams for my 2005 Prius, but they don't match on the section with which I am having a problem.

    The first is from adhol.com (Automotive Hobbyists), which I believe is now wiring-diagram.com. The second I believe is a snippet from Toyota that I downloaded from toyota.justanswer.com.

    First, let me describe my problem....

    And when I insert a new AM2 15 A fuse (second down on the right (as you're bending over the hood) in the big L shaped main fuse box under the hood on the driver's side), the car powers up, but the triangle light comes on, the MPD says "problem" and then in the upper right I get a picture of an orange car with an exclamation point in it. A few seconds later, the ICE fires up and then smoke comes from under the hood by the driver's side fender (possibly from under the driver's side headlight). Then the AM2 fuse blows, and the instrument display starts flashing on and off with no flash pattern. I have to replace the fuse in order to be able to shut the car down completely.

    Another member described something similar with the AM2 fuse (just not as extreme), and it turned out to be the INV W/P (inverter water pump / coolant pump) motor was bad.

    Now here's the diagnostic challenge...

    Both diagrams show that the AM2 fuse lead goes to exactly two places. The white wire goes (through a connector or two) to the AM2 power input on the Power Control ECU. Both diagrams agree on that part. The other side of the fork (the black wire) goes to the contact on an SPST relay, normally open. Both diagrams also agree on that.

    However... the adhol.com diagram shows that this relay is the INV W/P relay, with the other side of the SPST relay contact going to the Inverter coolant pump, located underneath the left (driver's side) headlight. The Toyota diagram shows that this lead goes first to the contact of the IG2 relay, and from there it goes to all four fuel injectors.

    Two things make me think that the Toyota diagram is wrong. First, the smoke is coming from the driver's side, not the passenger side where the fuel injectors are located. Second, someone else here had a similar problem with the AM2 fuse blowing and it was the INV W/P coolant pump motor that appeared to be the culprit, including by the computer code. Those two things would have to be sheer coincidence if the Toyota diagram is correct.

    So the reason I'm posting here is... does anyone know from DIRECT experience which diagram is correct, or possibly know from the horse's mouth of someone who has direct experience? Please do not respond if you are merely speculating or repeating what you have read from one book or another, since I have conflicting accounts in published books, and such a response will do me no good.

    Thanks in advance for anyone who can help with this.

    Scott
     
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

    Joined:
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    Location:
    Green Valley, AZ
    Vehicle:
    2015 Prius
    Model:
    Two
    Hi Scott,

    The 15A AM2 fuse powers several circuits, including:

    Engine Control
    Ignition
    Interior Light
    Push Button Start System and Hybrid Vehicle Immobilizer System
    Shift Control System​
    TOYOTA Hybrid System

    (Source: p. 372, 2004 Toyota Prius Wiring Manual. That page also shows the six pages that you would look at to see the circuits powered by that fuse.) See techinfo.toyota.com if you wish to access this.

    The circuit diagrams you are referring to apparently show only partial circuits. Good luck finding the short.
     
  3. 3prongpaul

    3prongpaul Hybrid Shop Owner, worked on 100's of Prius's

    Joined:
    Jul 18, 2010
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    Location:
    Boulder Hybids, Boulder, CO
    Vehicle:
    2006 Prius
    Model:
    N/A
    I've seen this before. Inverter pump uses AM2. The smoke was coming from a shorted inverter coolant pump drivers side behind headlight. Unhook the electric cord connector from the pump and fuse should not blow. (You can run the car for a few minutes with it unhooked). Get a new coolant pump, check that the wiring harness is ok.
     
    SFO likes this.