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08 Prius. New Battery -- still dead car

Prius, 08, smart key.
Dead on Sunday am — nothing works. Not even with key in slot. Put trickle charge on the underhood postive and neg to body bolt. Got enough juice to open rear hatch (and dome light comes on )

Replaced with toyota battery. Neg cable taken off first, then pushed up out of the way behind carpet.

Still dead. Still nothing. Checked both batteries at Autozone. 94 and 100% — wasn’t battery in the first place. Checked clear window fusible link on top of pos post — still good. Can get locks and lights to work with trickle charge, but NOTHING if disconnected.

Now what?

sounds like a bad connection somewhere (or corroded). Or it could be a Hot wire grounded out. Good luck this is a hard one.

Lets look at it this way, no power with old or new battery…You said you connected a trickle charger from the positive battery post and negative to the body, now the dome light works etc…so the trickle charger is supplying some voltage now.

Take a jumper cable and connect it to the negative terminal on the battery first, then to the engine block and see if you get power back…if not remove from engine block and clamp the jumper to the body…

If either of these work it means you have a negative ground problem in the negative battery cable
going to the block / body. I bet if you removed the negative of the trickle charger and put it across the battery negative post you will have nothing…just my 2 cents

Missing voltage problems are usually a bad ground connection somewhere. Usually tricky to isolate, but battery strap and cables are the first place to look.

Have the battery posts and corresponding battery connectors on the wiring harness been thorougly cleaned and the oxidation completely removed using a battery post cleaning tool?

If there’s been any work done on this car recently, or it has been in an accident, it may be a wire or connecter has come loose somewhere. If so, any mechanic – preferably one trained in Prius electrics – could find that straight away I expect. It’s just a matter of tracing out the wiring with DVM meter.

I would bet that most real mechanics (not the kid at the quick oil change place) can find the problem with a test meter.

The 12v battery does NOT start the engine on the Prius, it’s the big battery that does it. I’d get it towed to a Toyota dealer and have it checked. It’s still under warranty so don’t do anything to mess it up.