Need help, reversed polarity installing new aux battery

I reserve judgement until the voltmeter has spoken.

 

Sounds plausible then.

If there's a repeat of the episode with a new battery, I'd be tempted to repeat the measurement right then (that is, while the car is in READY but showing warnings and showing low voltage symptoms). If it looks at that moment as if the converter has shut down, that might suggest it did take some damage, and isn't dead as doornails but maybe somewhat more prone to overheating or faulting out.

 

I won't say never, but it doesn't seem likely to me.

 

By "reinstall" the engine ECU do your mean to replace it with another unit or is there some procedure to reset it.

 

I meant that the OP should just physically reinstall the original engine ECU because it was likely nothing was wrong with it. It appears that after five pages of discussion, the OP concurred.

 

I'm glad that you were able to resolve the issue!

 

Hi. Hope somebody will be able to help.
Trying to fix my friend's Prius 2006 with smart key.
Old poblem: 12v battery was reversed polarity (before this the car was driving, just decided to replace it).
Fixes: Fixed polarity. Charged 12V battery. Installed new 100A white fuse at the front fuse box (it blow out). Checked all the fuses under the hood and in 2 places under the dash, and the ones at the 12V battery, all are fine.
Today's problem: When I put the key into the slot the key logo still flashes on the dash and the car doesn't start, start button doesn't light up with green or red. Smart key opens/closes the car, headlights and all other lights work.

Maybe somebody knows what should I check else?

 

The slot detects an RFID chip inside the FOB case. If it doesn't work when in the slot, did someone replace the FOB case without switching the RFID chip to the new case?

If it's a smart key system car, what does it do when you try to start the car with the FOB in your pocket? If it doesn't work, did someone disable the SKS by using the small button on the dash under the steering wheel (labelled as "key")?

 

Check ALL fuses - both in the underhood and underdash fuse boxes. Cross your fingers that the inverter wasn't hurt.

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The car is fixed and runs perfect.

The problems that have faced:
1. Replaced long white fuse 100A under the hood.
2. Replaced big square fuse (the one sitting on the 12V battery).
3. Keyfob was missing immo chip after case replacement (not fixed).
4. My luck the car has smart key, but the smart key button was in off position. So turned it on.
5. The dash lighted up, but the car didn't start.
6. Ran techstream and found some dc inverter code and P3000.
7. Replaced dc inverter. The car still wasn't starting. Showing only P3000. Ran data list and found 2 first blocks too low (5v and 6v).
8. Opened HV battery, charged two first blocks to match the neighbors and the car started.
!!! Before testing don't forget to put on and screw all metal covers on the HV battery. Otherwise the HV battery won't get ground and you'll get P0ADC, P0AE0, P0AE7 blocking the car from starting.

Finally took apart the inverter. And the only visual complaint was found is about the board installed on the bottom of inverter, where 3 wire A/C cable gets in.