Need help troubleshooting: P3004-131 + C1259 + C1310 + ( C1241 )

From everything I have read up on thus far, I seem to have some sort of HV system fault and feel fairly ok that it is not in fact related to any of my braking systems despite the skid ECU being inadvertently implicated as ChapmanF has pointed out in numerous threads around here.

FULL initial code list:




AFTER clearing all DTCs and rebooting:




FREEZE FRAME DATA from time of incident:

C1310 - HV System Malfunction




C0200 Front Speed Sensor RH Circuit




FREEZE FRAME DATA AFTER ALL DTC's CLEARED AND SYSTEM RESET:

P3004-131 High Voltage Power Resource



C1310 HV System Malfunction



All ECUs are online and communicating fine according to TS.
Here is a shot of the HV Battery Live data:



Using the P3004-131 workup, I am about to pop the top off the inverter assembly and probe some of the connections under the lid as the doc suggests.

As I mentioned in my initial thread that started this hunt, as I sit in the car with the driver's door open and put it as close to "ready" mode as I can to pull codes and poke around through the data, the 12V battery seems to not be able to keep up despite keeping all accessories and lighting in the car powered OFF AND also leaving my 12V 5A charger hooked up to the 12V battery while I am pulling codes... the dash and MFD just go completely dead after a little while.

Any ideas before I continue my dive?

 

installed brand new 12v today, still no dice. will continue down the list

 

checked frame wire continuity and for any obvious shorts to ground, none found. kind of waiting on a week's worth of rain to pass so I can get under the hood and pop the lid off inverter to finish probing...

disconnected and tested the circuit breaker no. 1 bolted to side of inverter and it tested out at 819K ohms... is that good or bad?



luckily all of this started before the rain so that much is mostly ruled out.

thinking I should pull the HV pack and freshen all its connections in my garage while I wait for the rain to pass.

 

I am mostly just trying to avoid wasting money on parts I don't need. It doesn't help I am having to carpool to the office daily now with a coworker who lives nearby and we work 530AM to 4PM most days at an office we live 45 minutes away from. So between commute, traffic, weather, and mosquitoes before dark that will carry you away, it is difficult to get anything done after work hours.

Luckily another coworker of mine lives nearby ABY Home - Prius hybrids sales and service Scottsburg Indiana FL location so I am planning on sourcing any required parts from either them or eBay.

When I attempt to power up I definitely get contactor / relay clicking from the rear HV junction area of the pack, I may record a slow motion video of it so I can attempt to listen to the number of clicks and in what order they occur, but I believe I get at least 3, maybe 4 clicks out of them. I am not afraid to test some HV live, just need to know what exactly to test / look for. I've got heavy duty rubber chemical gloves with cotton linings, welding gloves, etc. and a CAT III 600V rated multimeter.

I appreciate your attention and have been getting a bit of help on the side from another member here as well. Just want to test and verify as much as possible to narrow down replacement part(s).

In the meantime I am reading through inverter info where I can find it.


ADDITIONAL QUESTIONS / OBSERVATIONS:

In the P3004-131 faulted state, when I press the power button and attempt to ready the car and hear a couple relays / contactors engaging, should the 12V battery be getting charged by the DC-DC portion of the inverter or does the faulted P3004-131 state prevent that (assuming the inverter was functioning normally without any problems)?

 

12V system, dc-dc, understood. thank you.

I removed all bus bars and sense wire tabs, and cleaned them all with green scotch brite, wire brushes, and some vinegar/salt/baking soda, 99% isopropyl alcohol and re-torqued all stud connections to spec to eliminate any odd resistances, corrosion, etc. Tested all wires from tab to plug tip and all pass continuity / resistance tests. etc. I am confident my HV pack 's core is fine, but the junction box components are still a possible culprit.

you can listen to the relays attempting to power up and ready the car here:

https://youtube.com/shorts/rqCytwGIe1w



The HV pack measures 213VDC pack side. Min/maxed it on the output side of the contactors and only got 1.9VDC MAX on the output side, probed between output +/- frame wire connection studs on the output sides of the contactors.

So by my estimation, that means either:

A.) one or more junction box components are faulty despite all basic tests suggesting otherwise

B.) the Prius computers are able to determine a fault and send the disconnect signal to release the contactors faster than my multimeter is able to sense the voltage changes

C.) something else I haven't thought of?

Tests that have come to mind to run since I forgot to as I was getting swarmed by about 50 mosquitoes as I was trying to disconnect my brand new 12V so it doesn't get damaged in between tests and I can keep it topped up:

A.) probe min/max voltage between each contactor and car body/ground during power up sequence to see if one or the other is able to successfully pass high DC voltage

B.) temporarily bypass the service grip plug by removing HV pack cover and directly bridging pack studs with a temporary bus bar and shorting the extra 2 sense wires that the service grip plug normally shorts

C.) manually feed 12V to close contactors after failed power up and ready sequence while car still on, standing by. (risky I know, could potentially fry additional expensive components, etc. not recommended and probably won't actually attempt this.)

D.) probe / verify 12V signal status to main output contactors, possibly using min/max during an attempted power up sequence to determine whether the computer is passing 12V to them and/or holding the 12V to them

E.) finish probing connections under inverter cover as noted by the p3004-131 workup to possibly verify a definitively failed inverter

F.) similar to A.), disconnect all computers, sensing, etc and disconnect HV pack from frame wires, manually feed 12V to both contactors with HV pack side connections intact and see if contactors will pass HV pack voltage to output lugs with no load

G.) any other suggestions?





OTHER THOUGHTS/QUESTIONS:

1.) When individually testing contactors outside of system with 12V, must hold 12V to maintain main output (HV) connection.

When they are working in their normal integrated setting, does the HV hold the connection once it takes place or must the computer maintain a consistent 12V to the contactors to keep the HV connection alive?

 

Alright, I am not sure what else to check out at this point... running out of options, about to start replacing more expensive components.

I have checked and verified all wiring connections / relays / resistors / etc. all test good.
Toyota TechStream has valid communication with ALL ECU's.

The main codes concerned are: P3004-131 and C1310-156

• Prius will NOT ready itself, not even briefly for a second or two, and resetting all codes / pulling 12V power completely does not give any temporary relief either.

• Fault occurred out of the blue after a 10 minute ride to the highway, just as I was getting up to highway speed as I was merging onto the highway. (approx 65mph)

• Fusible link and all minor (mATC style) fuses have been removed and visually inspected, then re-inserted -- none found to be bad.

• 12V battery has been replaced with brand new one, terminals and all connections wire brushed / sanded / cleaned / etc.

• Precharge resistor tests out at 20ohms (in spec).

• ALL bus bars and sense wires have been cleaned and freshened, tested for continuity from tab to plug tip, per pin and re-torqued to spec.

• ALL modules currently around 7.6 VDC, all within 0.10 V of one another (from memory, can pull more detailed figures from TechStream and/or probably have a screenshot already).

• Service grip plug has continuity, 125A fuse looks flawless and tests fine, cables have minimal resistance, 0.1 ohm give or take.
• Additional service grip plug has valid shorting block when in locked position, tested live with multimeter, as well as manually bypassed with a bit of wire on another ocasion.

• ALL 3 main relays have been independently tested and test out the same.
• ALL 3 main relays are capable of passing the current 215VDC pack voltage from battery side to inverter side (with inverter leads and all other things removed / bypassed and manually switching the relays in question using 12VDC injected)
• ALL 3 main relays have been swapped with used, working units from ebay -- no change.

• NO signs of corrosion on current HV battery ECU. ( I even removed the board from its case to inspect it closer and it looks flawless and pristine -- no burn marks or anomalies, etc. )

• I even temporarily bypassed the service grip plug while doing some other manual testing by attaching a temporary bus bar and shorting the 2 pin "lock" sense connector that goes to the ECU -- no change in behavior.

• NO obvious shorts to ground anywhere nor codes that would directly suggest it

• Frame wires have continuity and low resistance from HV battery connection to inverter connection.

• NO obvious signs of corrosion / burning / melting / etc. anywhere else (main HV battery connection terminals, etc.)

• Traced, checked, and tested the wiring that runs from HV battery ECU to HV battery fan / fan controller / fan relay -- all pass 12VDC and continuity where they should AND I am also able to manually control the HV battery fan from TechStream

I am about to start with purchasing a used HV Battery ECU off Ebay unless anyone here has some additional wisdom for me. Really hoping it's not the inverter but those are currently my top 2 suspects.

Please help, I need to get back to work before I get into more hot water with the boss.

 

yes, 100%

negative, tested while bypassed, same result

negative, tested while bypassed, same result

negative, correct resistance value, passes voltage and continuity consistently, no issues detected

negative, manually bypassed by shorting pins with a piece of wire inserted into connector.
the only possible issue that could still exist is if there is a fault in the circuit board itself that takes the input from all the pins on the connector, since the plug pins, wires, etc all seem to be in excellent condition and intact

yes, I am aware... I really don't want to have to replace the HV Control ECU if I don't have to, since that could easily turn into a headache / can of worms and I'd rather not have to deal with reprogramming multiple units in the car if I don't have to.

I don't think it will do much for me either tbh... I am mostly just going off of all the anecdotal evidence I have read up on around the internet and hoping it could potentially be the "easier" fix.

yes I am aware

yes I am aware

The unfortunate reality for me is there aren't many posts online with my specific combination of codes, and even fewer posts online that confirm the solution. I know the 3rd Gen Prius has a known inverter flaw / failure mode and have seen similar combinations of codes posted elsewhere that always seem to implicate the inverter primarily, but also sometimes the Battery ECU / frame wire connections / HV Control ECU as well.

The other day when testing my System Main Relays (contactors) that connect the battery to the inverter, I was getting the full 213+ VDC out the inverter side of the contactors while the frame wires were disconnected, but as soon as I reconnected the frame wires to the inverter side of the contactors and attempting to start up, immediately went back to faulting out.

I think today after work, if the weather permits, I will disconnect the frame wires from the back side of the inverter and disconnect the battery ECU and inject 12VDC to activate the contactors and test the output voltage at the plug tips of the frame wires where they normally plug into the inverter to see if:
A.) I get the full 213+ VDC to the inverter plug tips
B.) there are any egregious frame wire shorts or similar I have not found yet

If that tests out okay, my next course of action will be to pop the lid off the inverter and examine some of the internal connections within, but my gut feeling tells me I am headed for an inverter replacement.

 

I'm trying my hardest to hold off a tiny bit longer in hopes of more tests or wisdom or an "ah hah" moment but I need a little help from the community.

( here is my resistor test btw: battery ECU and contactor plugs are all disconnected while I am shorting pins and injecting 12VDC to activate the smaller main relay that activates the 2 main contactors while the frame wires remain disconnected from the inverter in the engine bay)


when I disconnect the main plugs from the rear of the inverter and probe the inverter terminals themselves, they appear shorted (0.1 or 0.2 ohms I believe).


is that normal?
can anyone with a known good Gen 2 inverter in the car perform the same test for me and let me know?



If I can definitively say which component inside my inverter converter assembly failed, I am not opposed to doing a component level repair. I just want to be able to verify first. I see components of the inverter/converter assembly for sale on eBay for cheap and most of the 2G assemblies probably should have their thermal grease replaced anyways to help prevent overheating.



I tested the resistance of my frame wires and both show 0.05 - 0.10 ohms from inverter plug tip to battery terminal tip, so that's good.




when attempting to power on I get 3 or 4 relay / contactor clicks as shown here: https://youtube.com/shorts/rqCytwGIe1w
followed by an immediate "beep" with the MFD indicating "problem" and the red car with ! symbol.

another question I had, was wondering if anyone can help me confirm or trace the wiring / diagrams, is the service grip plug closed sense wires that must be shorted for computer to know it's in place and locked in correctly...

where do those 2 wires go into the Battery ECU's front main white plug that connects the hybrid battery with the rear wiring harness of the car?

I would like to short them directly at the Battery ECU's plug to make sure the signal is not being lost after the small white 2 pin service grip plug connector (which tests open/shorted as expected when lifting and closing the service grip lock handle in/out of its final locked position)

 

yes, in that picture, the frame wires ARE CONNECTED into the inverter up front as they would normally be during standard operation

the only test I have not explicitly carried out so far is the megger test but I really don't think I am dealing with a significant short to ground situation based on all evidence presented so far

good to know. if nothing else, I can boot the car once with the interlock disconnected and see if the system at least throws the expected code(s).

yes, curiously nearly all other isntances of P3004-131 seem to be accompanied by various other codes, including some " P " codes, none of which my system seems to be throwing.

I am waiting for another rainy day to pass so I can tear into the inverter and perform the last few tests from the P3004-131 workup. Based on those results, it will likely either recommend I replace the HC Control ECU or the Inverter/Converter assembly from what I can tell.

If possible, I would prefer to test and replace sub-components within my existing inverter assembly since the essentials can be found on ebay reasonably cheap and they probably all could use to be re-greased with fresh thermal grease.

Film Capacitor bank:
2004 - 2009 Toyota Prius Panasonic Inverter Film Capacitor G9023-47010-C-S2 | eBay
not sure I could validly test such a large bank

IPM ( Inductor Suppressor AKA: " Reactor " --

)
2004-2009 TOYOTA PRIUS HYBRID INVERTER INTERNAL IPM CIRCUIT | eBay
according to the linked video, this is just a coil of wire, so should be able to verify whether open or shorted

Internal IPM Circuit ( Converter Module AKA: " Boost Control Module ")
2004 - 2009 TOYOTA PRIUS HYBRID INVERTER INTERNAL IPM CIRCUIT PM400DJA120 OEM | eBay
looking for how this specific module works and whether or not it can be independently tested?


Additionally, I am getting 12V to the fuse box jump stud under the hood when the 12V in the rear of the car is hooked up, and none of my small fuses are burned up, nor the fusible link main fuse up front under the hood.

I am not getting any 12V charging when attempting to ready the car, so I am also curious if the DC-DC 12V battery charging circuit inside the inverter converter assembly could have failed and be causing what I am currently experiencing.

I was considering trying to disconnect the 12V output from the DC-DC 12V charging circuit coming from the inverter converter assembly but I am pretty sure that would throw its own code(s) and am not sure if that would or would not still prevent the entire car from readying itself assuming the DC-DC module was in fact the problem component inside the inverter converter assembly.

 

Just finished the last couple P3004-131 workup steps and from diagnostic tree step #11 I only received 0.50VDC rather than the 1.60V to 3.80V I was supposed to get.


Looks like Toyota wants me to replace the inverter/converter assembly. I would still like to get to the bottom of what exactly happened to my original converter so I will likely tear it apart later once my car is back up and running.

 

replaced entire inverter assembly with a used one from local auto salvage for $150.

problem is officially solved... finally.

thanks for the input all.

 

forgot to mention, fwiw, I clamped the coolant hoses and siphoned the tank empty before removing the old inverter to keep spillage to a minimum.

after installing the replacement inverter I filled it from the lower aluminum outlet elbow until the tank was at its full level.

I used two pieces of scrap coolant hose and some wine corks while performing the fluid refill. after some quick handwork, the loop should have very minimal, if any, air stuck in it.

I can see turbulence in the reservoir as it should appear. all seems well so far without any explicit coolant bleeding.

will likely monitor with TechStream the next couple of trips to keep an eye on temps.