Prius wouldn't start

The connector in your photo doesn't seem related to the current sensor, at least as far as I can tell from the 2006 wiring diagram I'm looking at. As for what that connector is, your fingers in the photo are in the way of seeing what wire colors go into it.

 

So where is that, if I may ask? And what were the wire colors, if you can say without too much trouble?

 

If you look very closely, there is corrosion on some of the pins of the orange connector. I would replace the battery ECU with a used one.

 

Interesting ... the 2006 wiring diagram doesn't call out a connector there ... just looks as if the B13 connector that plugs into the battery ECU just has three wires from pins 14, 15, 16 directly to the current sensor. Also doesn't show their colors. I guess those were considered battery-internal construction details.

 

Like Brian1954 I notice that the pins on the right side (in your photo) of the orange socket look a bit crusty, particularly on the bottom row.

I don't know why people always assume the ECU must be bad. Likely your ECU is okay, it is just the pins in the orange socket that look funky. Maybe you can clean them up and make them nice and shiny or maybe you can just replace the ECU.

 

A picture is worth a thousand words:

 

Deoxit

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Did you verify wire harness continuity from each nickel voltage sense tab to orange plug tip that connects to the battery ECU?

 

In lieu of just starting to throw parts at it, if you want to get to the bottom of it, you need to start your troubleshooting by verifying the hardware (ie. wire harness) you have connecting the hybrid battery to the ECU is intact by checking each individual sense wire's continuity from its sense tab on the hybrid battery/bus bar attachment point to the tip of the orange plug using a multimeter (in continuity / resistance / diode mode, depending on your specific meter's settings).

That will confirm whether or not there are any broken wires within the hardness bundle and whether or not it is even possible for the signal (ie. voltage) to make it from the hybrid battery bus bar stud terminal interface to the battery ECU in the first place.

 

Each of the wires you see at that orange connector has a far end too, at a terminal that sits under the nut at one of the module studs. And each one of those wires has to conduct all the way from that terminal to the corresponding ECU pin.

P0AFA is a code that is only set when at least one of those voltage readings is totally bogus, say two volts or less. There's no way two volts is a realistic voltage reading for a 6-cell NiMH module, even a really tired one at deep discharge, so this is not a code about any battery module being tired or undercharged; it's really saying specifically that the reading from at least one is plainly bogus, as you might see when one of those terminals or wires gets broken or left unconnected, or an ECU pin is kaput.

 

I would look at battery block voltage data from the battery ecu. Whichever one looks "wrong" will point you toward the problem circuit.

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