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fob is potentially defective

Discussion in 'Gen II Prius Care, Maintenance and Troubleshooting' started by dickkessler, Jul 21, 2010.

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  1. dickkessler

    dickkessler New Member

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    hi my girlfriend has a 2006 prius with two fobs, one fob works just fine opens/closes doors and red led illuminates, the other fob does not; I have replaced the cr 2032 battery, and verified that the battery works with a voltmeter. no battery energizes this fob as determined by depressing the membrane switches and NOT seeing any red led illumination. I could possibly fix the circuit if I could separate the two plastic housings. has anyone done this? if so I would appreciate the disassembly help. does anyone have any other suggestions of how to fix this fob, again the other fob works just fine so no issues with the car itself.
    thanks
    dick
  2. RobH

    RobH Senior Member

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    Disassemble the fob down to taking the battery out. Then spread the case by inserting needle nose pliers into the mechanical key slot. Use the pliers just enough to slide a dull blade into the opening, and work it the rest of the way around the case. The glue is weaker than the case (well, mine was...) so the case should not be damaged. You'll have to remove the old glue as it is no longer sticky. I used ordinary white glue to reseal the case. Don't use a strong glue or you'll never get it apart again.

    There are two active parts inside the keyfob. In addition to the circuit board, there is also a small leadless chip that is the transponder. Both are just jam fit into the case.

    Just for fun, scotch tape the transponder to the tip of your finger. Then insert that finger into the keyslot in the dash and press Power with the other hand. Be sure to not have any good keyfobs within range of the SKS system. The "finger in the keyslot" key works fine. When you turn the car off, the keyslot remains latched open until you press it again.
  3. Patrick Wong

    Patrick Wong DIY Enthusiast

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    I'm just wondering whether you confirmed that the fob battery is correctly installed: the + side should be facing you as you are looking at the installed battery.

    If that is good, then you'll probably need to purchase a new fob. Good luck.
  4. dickkessler

    dickkessler New Member

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    hi patrick many thanks, yes I have verified the position of the battery.
    best dick
  5. dickkessler

    dickkessler New Member

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    hi and many thanks for the how to.when I get a break today I will try that. I can also supply 3+ vdc to the leads with a separate power supply.

    best dick
  6. windstrings

    windstrings Certified Prius Breeder

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    OK, so whats the trick for changing the battery.. do you have to pry the whole thing apart as described or is there a secret slot I'm missing here?
  7. Patrick Wong

    Patrick Wong DIY Enthusiast

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    After removing the mechanical key, the major trick is that you have to hold the little slide lever with one finger while trying to slide off the cover with the thumb on your other hand. The cover may be difficult to budge, you need to be persistent.

    Another "trick" is that you need to have a very small Phillips screwdriver to remove the four screws that secure the CR2032 battery cover; I bought a set of those screwdrivers at Radio Shack and IIRC the 2 mm size works well.
  8. windstrings

    windstrings Certified Prius Breeder

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    Patrick, your stinkin awesome dude!... especially since I was right in the middle of trying to do it and you responded so fast... thanks a million..

    Your instructions were perfect... thanks!
  9. windstrings

    windstrings Certified Prius Breeder

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    Battery replaced... now works like a charm..... thanks...
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