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Thread: Replaced alternator and crap happened

  1. #1

    Replaced alternator and crap happened


    My son has a 2001 Protege. Battery light came on so he went to parts store to get battery checked out and turns out it was a bad alternator.

    I did a bit of research and called mechanic friend of mine, picked up an alternator from O'Reilly and swapped it out. Things went relatively smooth replacing it as far as getting the old one out and the new one in (jacked car up and did it from underneath).

    Here come the problems:

    1) Battery light still comes on and off. At first I thought the belt was too loose since it seemed to come on as approaching 2000 RPM's, so I tightened the belt some more. Didn't solve the problem so I replaced the belt just to be on the safe side. Still have the same issue. Both before and after I would always get 14+ volts measuring from different ground points in the engine compartment.

    I did also clean the battery cables, only the ground cable itself had a bit of corrosion on it, but cleaned it none the less.

    My son does have a souped my amp/radio installed, so I disconnected those to make sure they weren't causing any issues.

    2) Since replacing the alternator the car now has a very lack-luster acceleration. The best I can describe it is it seems like it is in 1st gear up to 5 MPH and then shifts into 2nd. There is that slight hesitancy as if it is shifting gears. I tried putting the gear shift in 1st and then trying to accelerate with the same problem, it still seems like it is trying to shift into 2nd.

    Checked transmission fluid and all that looks good.

    I'm not getting any DTC codes from the scanner.

    I'm only guessing here but I feel as if we some how loosened an electrical cable that is related to the transmission and that is causing the battery light to come on and the transmission to act screwy.

    Any suggestions welcome.


  2. #2
    Check all your ground wires, also make sure all your power wires are clean and tight. I have had alternator's with faulty regulator's that were intermittent and it drove me crazy trying to figure out the problem.

  3. #3
    Update: Grabbed my multimeter rather than use my quick tester. All my circuits were testing good, about 12.5v with the engine off.

    Started the engine and my voltage shot up to 17.5v! Turn the engine off and it was still 16+v, although it was declining.

    Drove back to O'Reilly and it passed their tester twice. Even though I showed the guy it was at 17+v on the multimeter they wouldn't swap it out. Said I would have to wait until tomorrow when the store manager was there.

    Needless to say I am highly upset, to put it in mild terms. We shall see what happens tomorrow.

  4. #4
    It was a bad alternator, although it "checked out good".

    Bad news, it damaged the battery enough that the battery had to be replaced. Good news, the battery was still under warranty.

    What bothers me more than anything is that for someone with no Mazda experience, this still should not have taken more than two hours. Instead it took three days. No warranty on time.

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