Rear Defroster

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by PriusNewbie32, Nov 15, 2016.

  1. PriusNewbie32

    PriusNewbie32 Junior Member

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    My rear defroster will not come on. Just purchased a week ago. Fuse is not blown. Any idea what it might be or cost to get checked and fixed?
     
  2. DonDNH

    DonDNH Senior Member

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    Could it be a wire disconnected or loose on the rear hatch? Other possibility is there's a break in the heating element on the glass. You might be able to use a multi-meter to troubleshoot the element as well as ensure power is getting to the rear defroster.
     
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  3. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Yeah if completely not working, maybe some main connector wire is loose? If it was just a line or two, then more likely the problem would be a break in the line. There's kits for repairing that case, use conductive paint.
     
  4. PriusNewbie32

    PriusNewbie32 Junior Member

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    The heating element doesn't look broken. Do you know where the connection wires are in the hatch? The LED light does not come on when the button is depressed. Thank you all for your help!

    Posted via the PriusChat mobile app.
     
  5. DonDNH

    DonDNH Senior Member

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    I believe there is a connection point on both the left and right sides near the plastic trim around the real glass that are visible when the hatch is open.
     
  6. PriusNewbie32

    PriusNewbie32 Junior Member

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  7. PriusNewbie32

    PriusNewbie32 Junior Member

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    I'm having a hard time finding these connections. Do I have to remove the piece of plastic between the two glasses?

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  8. DonDNH

    DonDNH Senior Member

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    I didn't have to with my old Prius. Can another owner of a 2010 check to see if they see wires connecting to the defroster filament on the rear glass? If so, post picture of the connections?
     
  9. PriusNewbie32

    PriusNewbie32 Junior Member

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  10. Mendel Leisk

    Mendel Leisk Sand Pounder

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    I don't see any visible connectors on mine either. You're gonna have to pull plastic pieces off to find them. That said: if they're so well protected, makes me wonder if they're the problem. Could be. Or could be something in the rear defog switch?
     
  11. PriusNewbie32

    PriusNewbie32 Junior Member

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    I'm starting to wonder if it's the switch because like you said if they are that protected how they would come undone

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  12. ChapmanF

    ChapmanF Senior Member

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    Right. With your earlier post saying the LED light doesn't come on, I'd be looking at the switch, switch wiring, body ECU, relay ... if it were a bad connection back at the glass, the light would come on but the glass wouldn't heat.

    -Chap
     
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  13. PriusNewbie32

    PriusNewbie32 Junior Member

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  14. ChapmanF

    ChapmanF Senior Member

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    Someone with certain knowledge may chime in, but I wouldn't be surprised if it's in the instrument-panel junction box, under control of the body ECU, maybe in response to a multiplexed signal sent over from the A/C ECU. The wiring diagram will say for sure, and the repair manual will have good procedures for tracing your problem (since, as you might expect given multiple ECUs, maybe multiplex communication, etc., you might want a systematic approach to tracking it down).

    I'm pretty sure Techstream (with a Mini VCI / VxDiag, etc.) will let you interrogate the A/C ECU, command the defroster on and off, and see what happens, to narrow down whether your trouble has more to do with the switch, or relay, or something further downstream.

    -Chap
     
  15. PriusNewbie32

    PriusNewbie32 Junior Member

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    I had a family friend that's a mechanic check it. He is pretty sure it is the switch. I called Toyota and they said the switch is in the instrument cluster. About $530
     
  16. ChapmanF

    ChapmanF Senior Member

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    Yup, this assembly, $530 list, $380-ish new at discount, $55-ish salvaged.

    The nice thing about knowing the price to replace the whole assembly is it puts an upper bound on what you might have to spend if you try to just disassemble it and clean up the switch, and end up bricking it. Then you can feel more free to just give it a try, and probably succeed.

    -Chap
     
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