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Where is the fuse for ABS Motor Relay?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by rjcress, Nov 29, 2019.

  1. rjcress

    rjcress Junior Member

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    Where is the fuse for ABS Motor Relay?
    In step 7B in the image I got 12.5v from the ABS motor relay 2.
    I got no voltage on the ABS Motor relay 1 (the upper one).

    I found the 25A fuse for the MTR relay 2, but can't figure out where the fuse is for MTR relay 1.
    The engine room fuse & relay box cover shows that the ABS-1 fuse is on the left side... but the space it shows the fuse should be located has a long white box with a clear cover. It looks like a buss bar. I can't find the fuse.
    upload_2019-11-29_20-43-15.png
     
    #1 rjcress, Nov 29, 2019
  2. rjcress

    rjcress Junior Member

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    Maybe these pictures will help...
    [​IMG]
    [​IMG]
     
    #2 rjcress, Nov 29, 2019
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  3. rjcress

    rjcress Junior Member

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    After reading a few other posts it looks like the long white thing that looks like a bus bar with a clear cover is called the fusible link. It appears to be a positive bar at the top with a little connector sticking down which is the fuse to the connector down below. Am I understanding this correctly, that I should be able to measure 12v at the top bar, then move the + voltmeter probe down to below the thin fuse section and get 12v if the fuse is intact? If so, then it appears that the fusible link is intact.
    I've read this post, which was really helpful: How to change Fusible link under hood | PriusChat

    I'm thinking my next step is to remove the fusible link so I can check continuity from the output of the ABS-2 fusible link to the relay connector.
    *And I just noticed that I got the ABS-1, ABS-2, MTR1, & MTR2 labels wrong on the fusebox image in the prior post. Sorry.
     
    #3 rjcress, Nov 30, 2019
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  4. rjcress

    rjcress Junior Member

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    Solved! (I think)
    The ABS fusible link is fried. I just didn't see it from the angle I had looked. Swapping the fusible link now.
     
    #4 rjcress, Nov 30, 2019
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  5. rjcress

    rjcress Junior Member

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    Yep. I swapped in a good fusible link and all is working again. :)
     
    #5 rjcress, Nov 30, 2019
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  6. Phil Schuyler

    Phil Schuyler Junior Member

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    I realize this is quite old but I'll ask anyway.
    @rjcress did this ultimately fix your issue? I'm dealing with the same thing and found my 30amp fuseable link blown. I replaced it and went for a drive where I intentionally slammed on the brakes in wet weather to activate the ABS. On the third aggressive stop the fuseable link blew and the dash lights came back on.
     
    #6 Phil Schuyler, Oct 23, 2023
  7. ChapmanF

    ChapmanF Senior Member

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    One way I have seen a brush-commutated motor go bad was where carbon dust worn off of the brushes got so well packed into the gaps between the commutator segments that eventually it could conduct right across from one brush to the other and blow fuses.

    You could have the pump motor worn out like that, or just some other intermittent short in the wiring. One thing it won't really depend on much is how aggressively you stop, or whether ABS is used. The electric pump there isn't just used for ABS; it runs every time the system needs its operating pressure replenished.

    The pump does have two speeds though. The ABS MTR 1 circuit includes a resistor and runs the pump at a lower speed (explaining why its fuse is just 25 amps). The ABS MTR 2 circuit runs it at full speed.

    If you apply the brakes a bunch of times in succession, you can use enough pressure that maybe the ECU kicks the pump up to full speed to catch up. Maybe you don't even have an intermittent fault at all; there could be a solid fault that will blow the ABS-2 fuse every time full pump speed is called for.
     
    #7 ChapmanF, Oct 23, 2023
  8. Phil Schuyler

    Phil Schuyler Junior Member

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    I verified that the ABS MTR 2 relay makes clicking noises on the bench but I think I'll investigate the wiring relating to the MTR 2 circut.
    Any other ideas?
     
    #8 Phil Schuyler, Oct 24, 2023
  9. Phil Schuyler

    Phil Schuyler Junior Member

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    I suppose the blown fuse could have happened on the first aggressive stop but the lights aren't triggered for some time.
     
    #9 Phil Schuyler, Oct 24, 2023
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