P3004 - High Voltage Power Resource Code

Normally when you power up the car, the hybrid control ecu controls the three HV contactors (relays). One is for the pack (-), one is pack (+). A third is smaller and that one switches (+) in through a resistor which limits current.

So the (-) and (+ resistor) are turned on first. That gently supplies power to the inverter - if there's a problem then the low current through the resistor reduces any hazard. If voltages check ok, then the normal (+) is turned on and you're good to go.

The P3004 write up suggests that the HC ecu doesn't see the expected voltage at the inverter when it turns on the contactors.

I would go over all of the high current connections that were disturbed when you did the pack replacement. Every heavy orange cable connection at the battery modules and all the contactor studs. Maybe something wasn't fully tightened.

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There's another reason for the resistor besides just "if there's a problem". There are some big capacitors inside the inverter. To make sure they don't hold a dangerous charge for a long time with the car off, things are arranged so they discharge within several minutes of turning off the car.

That means they are normally completely discharged by the next time you start the car, and if the car just turned on the normal (+) and (−) contactors together, there would be a giant slosh of current into the empty capacitors, which wouldn't be good for anything, including the contactors. So the resistor is used first, and it allows enough current so the capacitors still charge pretty fast (within a fraction of a second), and then the other contactor closes and everything is fully online, but without a giant slosh.

 

You'll probably get more quickly to a solution by sticking close to the troubleshooting instructions for the code that you have.

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