My VSC light wont turn off

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by mywhitenoise, Mar 29, 2009.

  1. mywhitenoise

    mywhitenoise New Member

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    I had to change the battery on my 2005 Prius, and after I installed the new battery (bought from Toyota) the VSC light stays on permanently. Anyone know what's wrong?
     
  2. jayman

    jayman Senior Member

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    Did you fully charge the battery before installing? Is everything else working ok? Any codes?
     
  3. mywhitenoise

    mywhitenoise New Member

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    Yeah the battery should have been fully charged, after I installed it the MFD said it was at 12.5 Volts. The car is working okay, but everything was reset (he parking beep, the radio stations...i'm not sure about my navigation spots, hopefully those aren't reset). And yeah, thats the only code that's showing. Not sure why its staying on.
     
  4. JimN

    JimN Let the games begin!

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    The battery should have been fully charged but 12.5v is not fully charged. The VSC icon is a light, not a Diagnostic Trouble Code. If you don't have a ScanGuage go to an auto parts store that will do a free scan for codes and charge the battery.
     
  5. Mike Dimmick

    Mike Dimmick Active Member

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    Make sure that you've connected the brake control power supply properly. This is a box of capacitors next to the 12V battery. It's used to support the 12V supply for long enough, should the 12V system fail, to open the valves connecting the master brake cylinder to the front brake pistons.

    The 2G Prius is a dual-circuit brake system design, where normally the pedal force moves a 'stroke simulator' piston. The force is measured with a pair of pressure sensors. The car then decides how much total retardation force it needs, finds out how much regen can achieve, and applies the friction brakes to balance the car and make up the difference. In sharp braking, regen is ignored because it can't react quickly enough and all braking is done with the friction brakes.
     
  6. jayman

    jayman Senior Member

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    X2 for above

    12.5 volts is NOT fully charged. Did you FULLY charge the battery *before* you put it in the car?

    You have to use caution when removing the battery, as the capacitor box can cause issues.

    Remove the battery, fully charge it, and reinstall it. Don't forget the vent tube. Ensure all connectors - including for the capacitor box - are properly secured
     
  7. mywhitenoise

    mywhitenoise New Member

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    I just called Toyota, and they said they have to reset the system for $150...which is the price of a ScanGuage. It's ridiculous how much they charge just for that.
    JimN mentioned above that some auto parts store will do a free scan for codes, anyone which stores do that for free?
     
  8. jayman

    jayman Senior Member

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    That sucks. Swing by an auto parts store and see if their scantool can delete the VSC warning
     
  9. JimN

    JimN Let the games begin!

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    Around here AAMCO and Auto Zone have advertised the free check. Call around. Something that takes 2 minutes can create a lot of goodwill.
     
  10. johntpr

    johntpr Junior Member

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    You can't just clear the code by disconnecting the battery. There is a procedure, I'll get to that in a minute.

    Generally if the ABS/VSC light is on, your ECU is trying to tell you it thinks you have a problem. You should check it out. Otherwise, it will just come on again. The good news is, you can start the process the same way you'll eventually clear the code.

    First, connect terminal 4 and 13 of the OBD-II socket (under the dash in front of your left knee) with a jumper wire. (Those are the 4th from the left on the top and the fifth from the left on the bottom.)

    Turn the ignition to on. You'll notice lots of flashing lights, but just pay attention to the ABS light. Normally, it should be rapidly and steadily flashing, twice per second. If it has stored a trouble code, it will instead be flashing a pattern that will coding a two-digit number. There may be more than one code being flashed out. It will just repeat the code over and over, so you have plenty of time to figure it out and write it (them) down.

    NOW you can clear the codes. Just tap the brakes rapidly 8 or more times, about two taps per second. You don't have to jam on the brakes, just tap them enough to blink the brake lights. If you're successful, the ABS light should return to its normal fast blinking. Now remove the jumper wire, and finally turn off the key.

    Now when you turn on the key, the ABS light should just do its normal light for three seconds and go off. If it comes back on, you still have a problem
     
  11. jayman

    jayman Senior Member

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    I've gone through the service manual. Where exactly is that jumper wire procedure documented? All mention of retrieving diagnostic codes involve the Toyota DLC handheld tester, or the newer Panasonic ToughBook version
     
  12. johntpr

    johntpr Junior Member

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    It's not documented there, but it works. I did on my Prius this week after a brake repair. Just remember..your not pushing start button all the way to where the car is running..just to the point where the dash lights come on. With the jumper wire in place the touch screen will also bring up a diagnostic screen, but I didn't have to pay attention to that. Toyota wants you to use a scan tool that works with ABS systems...and that is the right way. But for do it yourselfers, the method I describe can save you from paying someone to do.
     
  13. jayman

    jayman Senior Member

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    Thanks. Just curious, what sort of brake repair did you have to do?
     
  14. jayman

    jayman Senior Member

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    Just curious about one thing. Considering that the Prius has a lot of manufacturer specific ABS and brake codes, how can you access them with a blinking light sequence when they are communicated over CANBus
     
  15. jayman

    jayman Senior Member

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    Ok this is the Prius DLC/OBD connector

    [​IMG]

    This is the pinout detail for the DLC/OBD connector

    [​IMG]

    Am I missing something?
     
  16. jayman

    jayman Senior Member

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    So, according to the service manual, Pin 13 *does* have a use

    [​IMG]

    Ok then ... poof
     
  17. johntpr

    johntpr Junior Member

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    This is where I found info....I had a leaky wheel cylinder that required bleeding that wheel cylinder....afterwards my brake,abs and vsc lights were on. I guess computer sensed loss of pressure. It isn't a Prius forum (the attached link) ..but I figured it was worth a try to turn off light and it does....as far a blinking codes...I didn't try to deciper or notice if they were flashing in a pattern


    How to reset ABS light? - Toyota Forums :: Toyota Nation
     
  18. jayman

    jayman Senior Member

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    If you have a 2004 Prius, it is IMPOSSIBLE to "bleed" the brakes without using the Toyota specific tool: either the older handheld, or the new Panasonic ToughBook version at dealerships

    Any attempt to "bleed" the brakes just by stepping on the pedal while opening a bleed screw, especially at the rear brakes, will result in the system entering a failure mode.

    As far as "blink codes" the factory schematics speak for themselves
     
  19. jayman

    jayman Senior Member

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    Just out of curiosity, I checked the electrical schematics for my 2007 FJ Cruiser

    [​IMG]

    A similar situation exists for pin 13
     
  20. efusco

    efusco Moderator Emeritus
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    Pin 13 is POWER

    You short together pins 4 and 13, you could wipe out a lot of circuits!
     
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