Strange electrical issues

[ARS_Lurker]

1999 Saturn SL2
250,000 miles
Original Engine/trans

Driving home yesterday from work and some funny things started happening...
Speed was about 25mph and the tach suddenly started dropping and the brake light in the instrument panel came on. The engine never slowed down to coincide with the drop in RPMS the tach was showing. I certainly still had brakes as well. It did this three times and then behaved normally for the rest of my hour commute on the interstate at 70mph.
This morning, it did the same thing again but only once. Speed at the time was about the same 20-25mph. Engine again was unaffected. Now the doors wont lock or unlock with the remote or switch in the doors.

The only recent change was a new Die-Hard Gold battery a month ago. I got 7 years out of the last one before it quit on me.

Any thoughts?
Mike

[ARS_Lurker]

Well, since the battery is clear dead now, I am guessing I either have a bad one or an alternator that is not charging. Sound right?

[ARS_Lurker]

More details...

No lights, door locks or anything electrical after I shut down the car in the parking garage yesterday. I pulled the battery and had it tested. It was fully charged and passes a 700CA load test.

Given that test, I would think the alternator is good as well. This sounds to me like a problem between the battery and the underhood fuse box or the box and the harness. The 30A fuses look ok but I will need to test them to be sure.

There is a heavy gauge red positive wire from the battery to the box and a similar black wire that I assume goes from the box to the starter. Since I have no power to anything, about the only thing that I can think of is that red line from the battery has something wrong with it or I lost the ground?

What should I focus on?

[OldNuc]

You have a battery cable problem. Check both the positive and negative cable at the battery. Verify that the terminal is actually tight at the battery when the bolt is tight. Do not get carried away with tightening that bolt either as it will strip out. Look for a whitish deposit on the connector pads and corrosion under the plastic cover at the point the cable is crimped to the contact pad. It is usually a defective positive cable.