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Thread: Transmission won't change gears in "Drive", but changes gears fine in manual mode

  1. #1
    Registered Member

    2002 Mazda Protege5

    Join Date
    Jan 2019
    Tilbury, Ontario Canada

    Transmission won't change gears in "Drive", but changes gears fine in manual mode

    Hey everyone, been trying to research what could be wrong and have found very little. I was having some engine and transmission issues in my 2002 Protege5, so I replaced them with the engine and transmission from a 2003 Protege5. The only difference was my 2002 had the automatic transmission with overdrive, and the 2003 had the automatic sport mode. I did swap over the shifter, cluster, and wiring harness. The car starts and drives fine, but the transmission won't change gears when it's in drive. It does change gears perfectly fine when it's in manual mode. It did not do this when it was in the 2003.

    Am at a loss of what could be wrong, any help is greatly appreciated!

  2. #2
    The Diagram Dude pcb's Avatar

    2002 mazda protege 5

    Join Date
    Jun 2011
    ontario, canada
    I don't have an automatic and know little about it but looking at the wiring diagrams, the sport AT has some extra inputs to the ECU that aren't used on the 2002 AT.

    There may not even be a wire in the connector on the ECU to feed to your harness.

    It's possible that the ECU is different as well but it could just be the wiring.

    I'm guessing if you swap your ECU and the harness going to it all the wires and connections should all be there.
    Assuming you still have access to the donor car.
    The Diagram Dude

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