Multiple Codes: Is it the HV Battery or something else?

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Once you have reliable 12 volt power, you can begin to diagnose other issues.

 

I don't have all those codes memorized. The Uxxxx codes generally indicate problems in communication networks between ECUs ... could result from wiring damage, connector corrosion, or (often) aftermarket gadgets plugged into the car spamming the networks with unexpected signals, if you might have any of those in the picture. C1259 is just a code from the brake computer reporting that the hybrid-control computer has told it there is an issue there. C1310 reminds me of a brake system code, but don't quote me on it.

You say you have Techstream screenshots. That information would be helpful (not that you have to post the images ... you can just transcribe the specifics ... Techstream will show you which ECU each of those codes came from, and that helps you find the right section of the manual to read more about them. Techstream generally also gives you a little one-liner summary of what each code means, though it's rarely detailed enough to conclude what's going on without looking it up in the manual (and sometimes it's just plain inscrutable).

Sometimes people see a collection of codes and conclude the car must be crazy and reporting things randomly. If you avoid that trap, you can find it even helps you because by the time you've checked the manual for the actual conditions that trigger each code, and started to reason out a picture that accounts for all of them, an explanation starts to fall into place.

If you look up the information and it doesn't explain itself to you right away, you can always add it here and get more heads working on it.

-Chap

 

Note, this is the original 12v battery

In a 2006? Yikes. I wouldn't immediately invest in a new battery, but I'd disconnect the neg cable on that battery and hook a known good battery up at the jump connection, put it through a few start cycles and see if that cures the faults.

 

That was likely the problem all along. It blew for the same reason any fuse blows: somewhere in the wiring downstream of it, or in one of the electrical parts connected to that wiring, there's a fault. If it's intermittent, it might not happen again for a while.

Troubleshooting it is just the usual drill; make sure you have a multimeter, and know where to look up the wiring diagrams to see just what is downstream of that fuse and where in the car, and strategically pick what to test in what order to best divide and conquer the possibilities.

There's a tool called Fuse Buddy that you can plug in place of the fuse (the fuse then plugs into it, so you still have protection) and measure the current flowing in the circuit. I find its shoulders are a little too wide to get into all the fuse slots in the underdash panel, anyway, but I think I'll be able to successfully trim mine down; the metal inside doesn't take up the whole space.

A fuse can blow either because of an overload (somewhat above the fuse rating over a period of time) or a short (some usually intermittent issue where some bared wire can touch a ground and conduct very high current, blowing the fuse very quickly). Sometimes you can tell by looking at the fuse whether it melted peacefully, or splattered its insides with molten metal.

With a meter connected to a Fuse Buddy, you can go through and grab sections of the wire harness and shake them, etc., to see if you detect an excess current. For more money than the fuse buddy, there are even gizmos that will self-limit the fault current when you shake the right spot, and just sound a honk so you know it.

If there are things with motors on that circuit, I've seen motors that use brushes go bad in a way that intermittently blows fuses. Carbon dust worn off the brushes can pack into the gaps in the commutator, until eventually it makes a conductive path right from one brush to the other, and when the motor stopped in that position, poof goes the fuse the next time it wants to start.

Again, first a look at the wiring diagram would give a good overview of what all kinds of things are served by that circuit.

-Chap