Can't fix this electrical issue.

So I finally said "f it" today and put the entire battery back together. One module was at 3100 MAh, but not reversed polarity. I snuck it in a block so the car isn't seeing it.

Dr. Prius life expectancy test showed 89.2%, higher than it ever has been (63% when I got the car).

I forgot to originally mention, part of what made me redo the hybrid battery is due to some electrical issues I thought were the fault of it, and turns out it isn't.

This electrical issue could of even been making the battery appear weaker than it is.

The car does the following:
1. Displays "problem" and beeps.
2. Red triangle appears, as well as a red car with exclamation point on the MFD.
3. VSC, brake control system (yellow one), and check engine lights come up on the dash.
4. Hybrid power is lost, and have to step harder on the gas to go anywhere.

The main issue is finding codes is impossible. There is no communication with the hybrid system when this occurs. The hybrid fan comes on full speed, but this might be a fail safe. All I can do is pullover, clear the codes on my handheld scanner, and drive again.

I've had the regular 12V battery checked and it's fine. Checked all kinds of grounds, connectors, etc.

I've tried to replicate the problem but can't. Stomping on the gas or brake pedals, turning the AC on, going up or down a hill, hitting a bump, changing gears, etc doesn't cause it. In fact it seems to happen in the most perfect of conditions (flat ground, city or highway speeds). It can happen once a minute or once an hour.

A couple other weird observations:

When at a stop light, the battery drains quickly with the AC on. When I ran the Dr. Prius test, it took 14 minutes to complete (the entire countdown plus 30 or so seconds) and the AC was on the entire time. The ICE is disabled during this test, and at a stop light in normal conditions, the battery can go into purple in 60 seconds. So why is having the engine kick on WITH the AC so much more draining than not running the engine AT ALL? I must wonder if something that runs when the AC normally does is draining the battery, and not the electric compressor itself.

 

The Dr Prius app can't connect to my car when this occurs, my handheld scanner can connect, but says no codes, even when the CEL is one.

Only scanner that could see any codes was the one at Autozone, and it said:

C1259 HV system regen malfunction
C1310 Malfunction in HV system
C1378 Capacitor communication circuit malfunction (there's a capacitor in the HV system? news to me).
U0123 Lost communication with Yaw Rate sensor.
U0124 LC with lateral acceleration sensor module.
U0126 LC with steering angle sensor module.
U0293 LC with Hybrid Control system.

Their scanners suggestion was 12v battery replacement, but it's fine.

 

I'll give that a try.

I think it's evident by the randomness that it's a power issue. I checked the voltage at the fuse box under the hood and it seems fine.

I also (this stuff has been happening before this) broke off one of the bolts holding the 12v battery done, which is gonna be fun to fix.

I do remember having to move some wire harnesses out of the way when working on my spark plugs, so it's possible something got messed up there, but I doubt underhood wiring would affect computers in the rear of the car.

 

No app shows any active codes. So my handheld scanner (CReader brand) seems to completely blank them out when I reset them using it.


Here are some screenshots from DR Prius. Not sure why the app shows the bar graphs moving up and down like a graphic EQ.


Weirdly..the IR of each module was at a flat 22.0 when I first ran the app after installing the battery.
The IR of block 10 seems high, but not enough to be of concern (at least to the app). 24 indicates a "minor concern" but the one crappy module out of the other 27 seems to not weight down the whole pack as much. The crappy module during bench testing was located in block 5. My life expectancy per the Dr. Prius app was around 13% before rebuilding the pack. So I'll take 89%, especially on a 14 year old pack.

 

It's strange how smart and how dumb this car's computer systems can be at the same time. All it says on the MFD is "problem" which is rather freaking useless.

I forgot to mention..before I refurbed the battery, when it was going this...all the gears (P, D, etc) would flash as well. It's not doing that now, though.

 

I might have to just bite the bullet and take it Toyota and pay the diagnostic fee. There's 14 or so computer modules not to mention hundreds of wires and dozens of grounds. I'd rather pay $80 than spend an entire day going through everything.
Hell..I accidentally knocked my rear cup holder off and there's a module behind IT.

 

Wouldn't be as large of an issue if it wasn't putting the car into a limp mode.

If those capacitors fail on the brake control module, could that be causing it? A bad ground would make sense if it was doing this when hitting a bump or something.

 

Oh boy, I'm now even more confused.

Waited until the car did it again, and this time it's worse. There was a couple times the engine cut out as well, complete loss of power for a split second. Not to mention..every time it does this...when I shut the car off, the engine continues to run for 3-5 seconds (like its not connected to anything and is freewheeling).

1st time it did this with my Bluetooth ELM connected, the car scanner app showed P0320 (fault in block 10), as well as P3000 (HV malfunction).

2nd time, it showed P3021 (fault in block 11), as well as P0A80 (replace hybrid battery).

Dr. Prius showed block 10 was at 17.33V when the other blocks were around 16.80V, and 34 mΩ resistance on block 10.

Funny thing is..neither apps showed the U and C series codes the autozone scanner was showing.

Also block 10 would be modules 19 and 20, which showed some of the best capacity and no issues.

The battery that had a crappy capacity would be module 10, on block 5.

So will the brake and VSC lights appear on the dash if the hybrid battery is acting up?

I'm to the point where I might just replace the entire battery, but I don't want to throw good money after bad if something else is doing this.

Is it possible that communication failures can "invent" problems with the hybrid battery?

Why can't my two code scanner apps as well as my Creader handheld scanner see these U and C series codes?

Also to clarify..it was doing this non sense BEFORE I touched the HV and 12V batteries. So it's not something simple like a nut being loose on a bus bar or anything.

 

Well I took the cover off the battery (with the orange plug removed ofc) and found that the orange main wires on the battery side of the contactors (relays) were very loose, almost falling off. I must of hand tightened these absentmindedly and didn't use a ratchet.

So a loose connection can definitely cause high resistance. It's possible the codes autozone found might not even be part of the red triangle.

I'm checking all the bus bar nuts too.

 

Great..just great..when tightening up the bus bar, somehow an arc was struck despite not being between two points of voltage.
Two bus bars went poof, and one module melted, and the other..the bolt broke off when taking the bus bar off.

 

Well I think the arc occurred between two modules and the seat frame. The hybrid battery assembly is supposed to be isolated from the car's ground/sheet metal so this exact thing doesn't happen, so I'm kind of stumped on how it even happened.

Here is some carnage. One module looks somewhat usable, but am afraid the pressure sealing integrity has been compromised since the plastic is warped around the terminal area. Surprisingly there was no voltage reading lost compared to other modules despite a high amperage arc event. In completely melted the inside of my ratchet, burnt my finger (it's not that bad, but hurt), and melted the crap out of the bus bar, you can see where a bead of it melted through the side of one module and rested on a small area like a bead of solder.

So now I need 3 new modules plus the entire wire frame, which is $86 from Toyota.