ECU issues when replacing battery - Jazz

Discussion in 'Jazz' started by Trespasser, Nov 24, 2009.

  1. Trespasser

    Trespasser Guest


    I'm the happy new owner of a 2006 VTI-S Jazz that needs a new battery, as it
    only cranks over slowly. There's still some charge in the battery and the
    central locking still works.

    When I bought a new battery from a Honda dealer, they said I would have to
    have the ECU attended to at a cost of AUD60.00 after changing the battery.
    Apparently if I didn't, then my mileage would be ruined, the Earth would
    come to an end, etc, etc.

    I've seen some posts about resetting the Jazz ECU by simply unplugging the
    unit for 4-5 minutes, and then plugging it back in. Is this what my Honda
    dealer is offering for AUD60.00, or will I truly be in need of more
    substantial ECU attention after the battery swap?

    Trespasser, Nov 24, 2009
  2. Trespasser

    Tegger Guest

    Disconnecting the battery resets the ECM. And that's where the alleged
    problems come in.

    I don't know what kind of emissions system Australian cars have, but if
    it's anything like North America's, you don't have a lot to worry about

    1) Disconnecting the old battery will erase all the "learned" presets that
    are stored in the computer. This includes idle, transmission "grade logic",
    fuel trim, and all the OBD-II "readiness monitors".
    These things will all take the computer a few days to re-learn, so the car
    may feel "funny" for a while until the ECM trains itself. If you drive a
    long enough distance, you may (or may not) notice a small drop in mileage
    until the learning is complete.

    2) American-market cars have security codes programmed into their radios.
    If the battery is disconnected, the security code needs to be re-entered
    before the radio will work again. I don't know if Australia has that too,
    but your Owner's Manual will tell you.

    But the ECM re-learning WILL happen, and will happen on its own, without
    any fancy hocus-pocus or equipment.
    Tegger, Nov 24, 2009
  3. Trespasser

    Dddudley Guest

    To avoid the hassle, will not one of those devices with the lighter plug
    and a 9 volt battery (or whatever) save all the setting for the short
    time that the vehicle's battery will be off line?

    With all the resetting that will be done on a battery change on a car
    with an entertainment system, GPS, etc. the $10 - $15 charged for those
    little doohickeys would probably be money well spent.

    OTOH, for the AUD$60 his dealer was going to charge him for this
    "service" he should get a kiss first. Service, that's what they do to
    cattle using a bull, isn't it?<g>
    Dddudley, Nov 25, 2009
  4. Trespasser

    Trespasser Guest

    Thanks Tegger and Dddudley.

    Thats 2 really good posts that have both helped me to understand and manage
    the situation.

    Very happy!

    Trespasser, Nov 25, 2009
  5. Trespasser

    Jim Yanik Guest

    depends if your car's outlet stays energized when the car is OFF,many cars
    shut off the lighter outlet when the ignition switch is off.

    Jim Yanik
    dot com
    Jim Yanik, Nov 25, 2009
  6. Trespasser

    DDDudley Guest

    Jim Yanik, wrote the following at or about 11/25/2009 7:49 AM:
    Whoa! Good catch, Jim. I completely forgot about that. That would be
    the case on my Accord and I don't recall if the outlet buried in the
    center armrest is also switched through the ignition.

    I know one thing and that's that I would NOT risk swapping out the
    battery with the ignition switch in the run or accessory position. I'm
    not sure but I suspect that could wind up costing me more than the
    AUD$60 Trespasser was about to be relieved of.

    That said, if the principle of floating a charge of 9v, etc. during the
    swap is valid in this regard, I suspect that there is a kit made with
    alligator clips to jump between the positive cable and ground and
    accomplish exactly the same thing without using the accessory power
    socket (formerly known as a lighter socket<g>)

    Hope it's not too late for Trespasser!
    DDDudley, Nov 25, 2009
  7. I have avoided the ECM problem on various vehicles I have owned by
    connecting an external 12 volt power supply to the battery cables. When
    the battery is removed, the cables are still receiving 12 volts so the
    ECM retains its memory. Has always worked for me.
    Kenneth J. Harris, Nov 26, 2009

  8. It's amazing that auto manufacturers have not implemented such a device,
    (short term capacitor), in their designs.

    This is just another reason that I drive old cars...

    Grumpy AuContraire, Nov 26, 2009
  9. Trespasser

    Tegger Guest

    Dealers have those tools expressly for the purpose of retaining radio
    security/presets and ECM-learning.

    But there ought not to be any sort of $60 charge (what the OP was told) for
    its use any more than there's an additional charge for putting the drain
    plug back during an oil change.
    Tegger, Nov 26, 2009
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