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The battery warning light on my 2000 Mazda Protege kept coming on after 35 miles per hour, so I took it to AutoZone to get it checked. The battery was bad (it did need a jumpstart in January) but the alternator tested fine. I got a new battery and the battery warning light came back on under the same condition.

Before I could get it checked, the car stopped working. Period. The battery connections seem fine. In half-second bursts, I can get some ignition but it quits quickly and the odometer blinks rapidly without key in ignition. I've checked the car to make sure its in park. It is.

What could be the problem? Electrical? Fuse?

  • @DavidLively, there's a good chance that this is the answer so you should answer the question.... ;-) – Bob Cross Apr 24 '18 at 18:30
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When you see multiple electrical failures at the same time, and you know the system has power, always start by checking your grounds.

Since you just replaced the battery, I'd make sure the terminals (and harness connectors) are clean and tight. If you see any signs of corrosion on the harness cable or the terminals, clean it with a wire brush. (There are a thousand ways to clean corrosion from these things - Google will help you out with shaky-yet-informative videos.)

On this engine, you probably have 3 or 4 grounds. I don't have the service manual, but I'd bet they are:

  • Near the battery, which typically branches off from the negative cable connects to the frame.
  • Definitely one for the starter. However, unless you've been fussing with the starter, I'd be surprised if that one has an issue.
  • Could be one on the cylinder head near the thermostat. All of my cars have at least one, and typically two, grounds connected to the head(s).

Also, check for continuity (with your multimeter) between the negative battery terminal and the frame and engine block. If that's bad, few if any electrical devices on the car will work.

Probably goes without saying, but when checking continuity against the frame, find an unpainted section. Most paint doesn't conduct that well.

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