Electrical problem with my 2001 Tundra

My 2001 Tundra with 175K has been working well but last week after the truck had not been used for 3 or 4 days I discovered that the battery was dead; the interior light didn’t come on when I opened the door and the starter did not even click when I tried to start it.

The battery voltage was down to about 3.5 volts, so I cleaned up the terminals and checked the “water” level in the battery. While I had the terminals off I checked the battery voltage again and it had gone up to about 6 volts. So I experimented with the three connections on the positive terminal and discovered that the battery would not discharge when only the towing terminal and the starter terminal were connected to the positive terminal. In other words, when the fuse box terminal was also connected to the positive terminal, the battery would discharge.

With the fuse box terminal disconnected the battery actually recovers to 10.85 volts so the battery “recovers” as long as the fuse box terminal is not connected to the battery.

Any ideas?

 

Sounds like a dead battery. When you put a load on it it takes away what little bit it has left. It has voltage, but its drained.

 

Semper Fi. Now get you a new battery and report back.

 

Thanks for the feedback! I hadn’t replaced a battery in this vehicle since 2014. Back then battery failure was a gradual event so you had some warning that the battery was about to fail.

This battery was working fine when I came home from a shopping trip. Four days later it wouldn’t even turn on the interior light when I opened the door. So I assumed it had to be some kind of wiring problem.

Anyway I took the battery in to Wal-Mart where I bought it and had it tested and found out it was bad, really bad. Turns out that most newer battery failures are like heart attacks—they don’t give you much warning.

Thanks for steering me in the right direction!