Tow Truck Driver Reverse Polarity Jumpstart

I appreciate learning more of people’s thoughts on this matter. I’m still trying to do some fact-finding to help me figure out what to do. (I’m also making other arrangements. I did call two hybrid shops, but they wouldn’t provide me an estimate for replacing the 100 amp fuse. Another shop sounds promising, however.)

From what other people have written on PriusChat, when a Prius has accidentally been charged with reverse polarity, it’s common for the smaller fuses to be blown as well as the 100 amp fuse, and sometimes other things have turned on. I don’t recall hearing about anything being melted, burn marks, or the 120/125 amp fuse on the 12v battery getting blown as well.

What I find concerning now is statements being made by AAA (shown below) that don’t seem consistent with what I’ve read elsewhere, and which might be wrong.

(By the way, I hadn’t actually filled out a formal complaint to AAA and still haven’t. After more than a week had passed since the tow, I had called the membership services about the tow truck driver, that the alarm system had sounded continuously while his portable battery was connected to the 12v battery, that the 100 amp fuse and three fuses had been blown, and that perhaps he had unknowingly used reverse polarity that might have caused some damage. Later, I had provided more information to an AAA investigator about what the Toyota service department had texted me.)

Take a look at the AAA response here:

“Even if the AUX battery was good before the service it would not be armed by a reverse polarity jump start. Before that happens the jump start pack cables and the main power cable to and from the AUX battery would melt and you would have signs of burned cable insulation, that is if the battery did not have a protection fuse, which it does since it states in the text that they found the 125amp fusible for the AUX battery in good condition, see below highlighted text. A reverse polarity jump start would have damaged the fuse, it wasn't. Therefore, a reverse polarity jump start did not occur and the Aux battery was not armed…”

I don’t recall other people whose Prius had experienced a reverse polarity jump talking about so much damage from a reverse polarity jump, including blowing the 125 amp fuse as well. And if the 12v battery is completely dead, perhaps that would be another reason why there wouldn’t be the additional damage specified above.

I also don’t know why he’s talking about the 12v battery being armed. The car hadn’t restarted. What does it mean for a severely depleted or dead 12v battery to be armed? (The objective of the tow truck driver might have been just to try to restart the car so he could put it into neutral and move it to his truck, not to charge the battery.)

 

Lol! I’d be sorely tempted to pay your way! If only there wasn’t a pandemic going on that could jeopardize your health along the way!

Thanks for confirming you didn’t have any burned or melted wires, and that the fuse in your trunk hadn’t blown.

I would normally be really interested in trying to replace the amp myself but after breaking my right arm and my left thumb at different times a few years ago, I lost lots of grip strength and my current ability to unscrew things is pathetic!

 

Thanks for describing your reasoning above, although my impression is that other people who accidentally jumpstarted with reverse polarity did not always fry their computers. Some were able to get the car to work after replacing the 100 amp fuse. Still, getting the codes might be really helpful.

Would the Toyota service department have been able to get the car connected to techstream? (I’m not familiar with techstream.)

According to some notes, there had been three fuses blown:

THRO 15 AMP (what’s that?)
AM2 15 AMP
15 AMP Dome

Also written in the notes:

Inspect for parasitic draw 35 MA

(The blown 100 amp fuse was found afterwards. Would that cause a parasitic draw?)

“DC/DC Converter needs removal to access relay block for disassambly”

There wasn’t anything written about what else was done to locate the parasitic draw.

 

rjparker, “Inspect for parasitic draw 35 MA” had come from notes that had been texted to me.

You’ve explained this is very low and “is a continuous drain on the 12v battery to keep certain computers operational.”

From what you’ve written, it sounds like the 35 mA drain is normal. Maybe I hadn’t understood correctly what was being conveyed by the very brief notes. I thought he had meant:

What’s causing the parasitic drain of 35 mA?

But another way of interpreting what was written is:

Inspected for parasitic drain. The measurement is only 35 mA. No need to investigate further.

I’ve been trying to make sense of what happened. I think that the service department had been under a lot of pressure and that at least one important team member had had to leave suddenly, perhaps due to Omicron. The majority of mechanics there would not be certified Prius technicians, so they could be at a loss about how to handle some Prius eccentricities and possibly making some incorrect interpretations.

I appreciate learning so much more here than I would have otherwise. The difference of opinions also shows how difficult it can be to figure out what’s going on, too.

 

Chapman, thanks for posting that picture again. Is there a picture of the inverter there? If so, what number is it?

I’m wondering how I can help a non-hybrid mechanic figure out how best to replace the fuse, even if that means removing or moving the inverter. (I think someone had written it might be possible to move the inverter to one side, but I don’t know if that was actually done.)

 

ammdb, you’ve helped me realize a bit more that maybe the folks at the service department aren’t fully knowledgeable about how to deal with this matter. Maybe they never wanted to work on my car at all, ergo the unreasonably high estimate.

 

Thanks for sharing that picture!

Is the fuse itself screwed in? The reason for pulling out the fuse box is to be able to unscrew the fuse from the side?

I imagine the Toyota mechanics, if they’re not certified, don’t feel authorized to pull the fuse box up because they don’t know they can do that safely.

It probably also takes a lot of arm and back strength to try to lift out the fuse box when it’s pretty far back from the front.

But it looks doable in less than an hour, right?

Do all the 1st generation Priuses look alike under the hood? The picture of a 2001 Prius would look like the 2002 Prius?

 

This is very, very helpful.

Although it might not be necessary to follow all the instructions, they’re a great backup to have on hand, just in case.