This is a 1999 Ford Mustang GT 4.6.

Electrical power completely shuts down and comes back on, the dashboard lights and gauges go crazy.

I put in a new battery, alternator and negative cable and haven't change the positive side yet. I also replaced the ignition switch, key, wiring harness that plugs into the alternator's voltage regulator. The battery gauge on the dashboard drops real low when it's doing this and then it comes back up to normal value again.

  • Is there a loose ground under the dash? Does the motor cut out?
    – Solar Mike
    Jun 16, 2019 at 20:13
  • don't no about loose ground under dash but yes motor cuts out, I push on the break pedal it will kill the car to. very low power. my guess is maybe bad Voltage Regulator
    – Jason E.
    Jun 17, 2019 at 2:21

1 Answer 1


Check the battery terminals. My old Mustang had a tendency for the terminals to get corroded. Cleaning (wire brushes) the terminals on the battery and clamps on the ends of the cables was usually enough to regain good electrical contact.

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