code C1391 and water in the back

Hello, I have an 05 Prius with 220k miles. Got the hybrid battery replaced by Green Bean Battery and then I replaced the 12 volt from Auto Zone with the last 2 years and like 20k miles. This new year I did notice more ticking and like cycling sounds from the engine area they stop at least for now. When I first got the vsc abs brake and (!) lights it was just after I added some older but authentic toyota anti freeze/coolant a couple weeks ago. I watched some videos and took it to O reily's auto parts for a obd2 code scan but he didn't print it out for me and the videos showed how to reset the lights with a jumper cable/paper clip in the obd2 port and 8 taps on the breaks. it passed the scan and the lights were gone on the next start. I had the bad weather this past couple weeks even have an home insurance claim because of it, anyway the same lights came back on after about an hours drive home. I thought I had already fixed the leak problem by the 12 volt and the back generally but I had only used bondo to patch around the battery area not used silicone on the rain "gutters" which I've now see a million videos on how to fix. So I sealed and sealed, pulled the drain plugs by the battery and the spare tire and generally got it dry back there. The driver's side rear cargo side carpet was still damp though when I drove it Today for a while, it is 35 miles into Nashville, TN. Eventually the same lights came back on, this time I go to auto zone they print out the report for the obd2 reading which is the "C1391: abnormal leak of acc press" but they didn't have any solution just more diagnostic work required. I do the jumper cable self diagnosis and again the lights go away other than the maintenance required but I am due for an oil change and tire rotation.

So I don't know, I think I am going to have Walmart, as usual for me, do the oil change and tire rotation and then take it to the toyota dealer to see about the error code. I mean it sounds like a few things might need replaced probably by me if I really think about the price of a newer one; I've done a few things on the prius anyway;

how big a deal is it if I just make sure the warning lights and my single error code wasn't due mainly to all the water in the back? in the manual, they didn't really cover what might happen if/when the water gets inside the back.

 

Well got it all dry in the back, the oil changed and tires rotated but the same lights came back on after about an hour and a half of driving. I haven't gotten around to testing the brake actuator but it sure seems like that is it.

We used to also have an 04 prius that we sold to friend who didn't really know how to take care of it so it has been sitting at his place, dead since before the pandemic. That would seem to me like a good place to start in looking for used parts but, he and I aren't like best friends, and I'm still not sure I want to even bother with trying to fix my 05. I suppose if I do try to and fix it, I'll be back in these forums because the info here is incredible, thanks!

 

I've watched more videos, read more, and now I took some photos of my old champ. Pictures probably tell the story but let me try and explain as well.

I mean I'll keep this one short. Looks like I got a leak with the white residue and below min on the engine coolant spot (I did top off the inverter coolant one with the toyota brand).

So my main questions are: should I refill the radiator coolant to confirm the leak and if so do I need to bleed it for air bubbles? or should I just consider going straight for the brake actuator since that is tied back to my c1391 code? Water pump and inverter pump I guess could also be replaced too in the same effort as none of those have been changed at least in 100k miles. Thanks

 

Well I've further upgraded my prius chat search skills I guess. I purchased an Autel MaxiAP AP200 OBD2 Scanner and it arrived today. Didn't take long to set it up and get a quality scan which returned my c1391 and another one in the abs section, I just forget but it looked familiar like 1250ish that points to the brake actuator. My understanding is that this scanner, like after I replace the actuator, this Autel scanner can do the brake bleed process. I was a bit confused about the toyota techstream possibilities when I bought this scanner so maybe I should've just bought the $30 vci cable to use with an (old) laptop and techstream software but this is very smooth esp. if I go shopping for a used prius I can just easily plug this in and check my smartphone for any and all codes before I buy. It is on sale on amazon for $51 after tax usually 70 just for the item.

As for the previous pictures, I did more research and at least with the main water pump, there aren't any signs of a leak from it, at least compared to what I've seen, plus no codes on it for me so for now I'm just focused on the actuator. I did chat up my old friend whom I sold the 04 prius and I looked into local junk yards. I'm thinking I will buy the actuator off eBay from this one seller who has multiple thumbs up selling this exact part going back years. It is a little pricier than some, $509, but has hassle free returns for 30 days including free return shipping, plus a 1 year warranty on the part. maybe my old champ isn't done after all...

 

Stuck with a stuck bolt.
Finally got the part after a weird shipping mistake and I am moving along fine until I get to basically the last bolt on one of the inverter orange power cable. The bolt I can't budge for the life of me is like the closest one to the windshield, attached to the orange power cable that has 3 bolts inside the inverter case and then 2 on the outside of the inverter again this is the one closest to the windshield. I got 4 of the 5 bolts out for that cable and have tried a little wd40, pliers and of course all my 10mm sockets. I could post a photo if it helps. it looks fine I don't get why it is stuck. I've also tried a flat a head on the side I got the bolt out of to wedge something just a little loose but no luck.
Is there a trick maybe or am I out of luck?

 

happy to report back lots of success and again thanks in part to prius chat posts. this probably will be a bit of another roundabout post but still likely would have be helpful for me on the c1391 brake actuator issue.

As of now I've replaced my original brake actuator with a new replacement part from toyota and driven it around the block. my autel bluetooth scanner told me i failed in the brake bleed but it did walk me through it. yesterday I learned that "front right tire" means passenger front tire but when I was doing the brake bleed with the autel scanner I thought right meant driver side. whoops. so i kinda ended up doing the bleed without a scanner except for the 3rd stage when after the front two tires, like the air bubbles eventually stopped with just the bleeder valve on the tire opened and a foot on the brake, but the 3rd stage is pump the brake 30 times in 30 seconds. I also messed up the final stage when the autel wanted me to open the drive front tire valve and I did passenger. after that I got the fail message from the autel but like constant beep sound had gone away and all four tires had been basically bleed, so I did drive it, first around my property for first braking tests and then around the block. I used up my bottle and a half of brake fluid so I need to get more to do it again but confident that autel scanner worked out for this project.

During the brake actuator install I wish I had just completely removed the inverter as it was in the way all day and it was a lot of reaching to begin with and I got a little sore in my lower back by the end. I eventually removed the inverter anyway to get in back in place easily so I also used up the last of my coolant that I had on hand. There are a couple nice videos showing the repair that both take place in real mechanic shops with real customers; Auto Scholar with Mr B and CarTechGA are the two youtube channel names.

Before I did the repair and after I got stuck on a bolt, I took it to an independent shop in Nashville called Import Specialists, they were very professional and know these cars very well. It was $250 for basically 2 checks, one for $150 for the dash light investigation and then like 100 for a normal check up. so including the 250 for diagnostics the total estimate of all the parts and repairs and tax came back at just under $4200. The main issue with that shop was they wouldn't buy the toyota part from the dealer in clarksville only their dealer in cool springs thus the brake actuator part was over $1800 and not the $1160 that I tried to get them to purchase and install.

So shopping right? The dealer in Clarksville, TN is called Wyatt Johnson Toyota and they have incredible prices but you have to buy them online even if you pick them up in person as I did. I took the list of parts I got from the diagnostic and in addition to the 650+ I saved on the actuator, the serpentine drive belt, front brake pads and rotors so much savings. the blet was 13, the pads are 42 the rotors in the 50s even the coolant is 18/bottle which is cheaper than the 3rd party coolant for toyota cars that walmart sells. like about 1400 for all the parts which is a different end cost than 4100. a 15 dollar "sockets that bite" socket set from kolbalt I got at lowes did the trick on that stuck 10mm bolt. all that cost and work compares well to me with buying a different like gen 3 prius with 140k miles for $9000 that I saw for saw but of course those would still have the og parts about fail. I was able to return for a full refund the used part I bought on eBay that didn't look. I guess I regret not buying a new traction battery when I bought a refurbished one a year or so ago but I did get the "lifetime warranty" from green bean so with just under 220k miles I am feeling good about another 30k+

 

Well I had a setback that I could use some help with perhaps.

I'm now getting the c1202 error code.

So I bought more coolant and brake fluid to finish my repair. I filled the inverter coolant over flow tank and did the bleeding process which seemed to go ok. When I switched to the radiator coolant, I used a paper clip to run the pump. did maybe that short something? I did see small sparks when connecting both ends.

Anyway after I did the coolant fills and bleeds, I went back with my Autel scanner to bleed the brakes/actuator again and despite now doing the correct tire in sync with the scanner it tells me it failed. I got the discharge of fluid at the end out of the front driver tire unlike the first time but now I have the error code. It maybe got a little low as I ran out again of brake fluid on hand but the brake fluid tank was down to the min level but it was still just above the min at the end, I was adding to full line and then watching closely after I ran out with one tire and the final discharge to go.

I bought more brake fluid and filled the tank, erased the code, did a new scan, said no codes, then I turn off the ig, take the btooth thing out, turn car all the way on, and still get that code with the lights on the dash of abs vsc brake (!). Should I try to bleed the brakes/actuator again or is there something more wrong? I should probably just get techstream vci cable from amazon.

 

More good news for me to report. I got the dash lights all cleared. I read around on priuschat here and of course didn't really understand the more detailed steps but I did see easier instructions to try first so what did it for me was unplugging/replugging the connector on the side of the brake fluid tank and then doing my Fonzi from Happy Days getting a free song played on the jukebox; just kinda bumped it a few times with my hand/fist. checked my scanner for codes, then turned it on all the way and no dash lights warnings.

So i still have a slight issue in that all 3 times I've bleed the brakes with my Autel scanner it says the process failed but it drives totally normal, I can easily come to a full stop going down on all the steep hills around here. I've done all 4 tires 3 times, 30 brake pumps in 30 seconds 3 times and twice have gotten the final discharge out of the FL tire at the end. One thing I noticed in my research was that it appears techstream has an additional first step of depressurizing the actuator before you remove it and I guess pressurizing it at the start of the bleed but my Autel didn't have that or I couldn't find it. But man I shopped techstream options from amazon and seems like luck of the draw with which seller to buy from.

The new actuator is so much more quiet than my old one. I still have the front brake pads and rotors, (and serptine belt, & license plate bulb) to change so perhaps after that I will take the car back to my new favorite mechanic, Import Specialists in Nashville, and let them get the 10000% perfect brake bleed. happy day!

 

Well my prius threw another error code at me after taking it out for some uber eats deliveries, error code P0A63 sub code 302. I've uploaded the freeze data from my Autel scanner.

It happened again today after I had gone back over my work installing the new brake actuator. I went back, unplugged everything involving the inverter that I touched as well as disconnecting 3 of 4 connectors in the hv ecu. Then I checked the torque on the mg1/2 bolts esp. they are at 71 inches /ft pound which they were not the first time it threw the code. The other thing big thing I kinda fixed was one of the electrical connectors, not the orange ones but the bottom one of the 3 on the inverter side closest to the windshield sorry about the lack of technical terms but anyway I read on here somebody like me as getting this code and other inverter codes after a diy brake actuator job and he just used electrical connector cleaner. See that one connector didn't snap the first time when I put it back together so I was worried about it but I couldn't pull it off so i left it but it did wiggle a bit so this time with that cleaner I think I heard it click and there's no wiggle at all with it. The only other thing about the inverter from my repair that jumps out is that I had to replace the two bolts that go on the outside of inverter case to connect the mg 1 (closest to windshield) orange cable bracket to the case, not the 3 on the inside that connect the power cable itself. I didn't buy the 2 toyota bolts, I could it is just quite the drive for me, so my new ones are just ever so slightly shorter but they are properly torqued.

The other thing I didn't do in-between the first time this error code showed up and the 2nd time was clear the code with my scanner. When I looked today it had the same code in both current and in its history. It took over 3 hours of uber to get a code unlike the first time which was much less than that. Also this time the dash lights went away after I turned it on a 2nd time; see it sends the code, my prius falls out of gear, can barely move but when I turn it off and back on I can drive it just still has the red triangle and check engine lights, so then this time today, i get the code, thankfully right at my drop off, so I turn the car off, drop my delivery, turn car back on, drive to nearest parking lot, I had my scanner with me this time, took the freeze frame data, turned the car back on and all the dash lights were off even without clearing the codes with the scanner or disconnecting the 12 volt. When I got home I went and cleared the codes.

So i've read about how toyota says to troubleshoot the error code, but I don't quite understand it. I bought my first multimeter from harbor freight the other day for about 10 bucks. Is that what I use? I couldn't really find a video about troubleshooting this code. I could use a multimeter for dummies type thing or just like basic english version of walkthrough that I attached as well.

 

Well I guess I made some progress but today it threw the same error code again P0A63 sub 302. I did get do 6 hours of uber eats in the last two days with the error code showing up just once at the end of the 2nd day. As soon as I scan it and restart, the dash lights all go away even without clearing the codes.

I'm really looking for specific guidance on these tests that the repair manual says to do. I've uploaded the 3 screenshots of the walkthrough. I did watch a multi-meter for dummies video by science buddies on youtube and by the end I was able to test my rechargeable AAs. The first screenshot I guess is the wiring overview, not sure what I'm really suppose to learn from that one other than the inverter is connected to the hv ecu. The hv ecu is located behind the glove box, if I understand correctly. I'm looking for the hv15 connector, again don't really know what that means exactly but the main issue is it is vertical in the car and the diagram there is horizontal so I 'm locking in on the slight differences in the shape of H15 connector, there's just the one indention at the bottom of hv15 the other one of the two middle connectors has two indentions at the bottom. So I think I can do that first test which is just the H15 connector, just set the multimeter to the right reading function, put the red wire into specified pin/spot and the black wire to a something grounded and then check that the reading is below 1 volt.

The 2nd test is where I get lost. This one involves the inverter. This is the "standard resistance(check for open)" test. Maybe posting has helped me figure it out now but am I suppose to like connect the red wire to the hv ecu connector by the glove box and the black to I10 in the inverter? because I would need longer cables to reach. But maybe looking at it now, is the H15 connector what the I10 connects to in the inverter? That would make more sense as normal cables can easily test those two. The first part of this 2nd test is MIVA (H15-30) - MIVA (I10-7). I'm not sure where the red wire goes, like the black wire in my multimeter should go to the specified pin/slot in the I10 connector which is what disconnects from the inverter; does the red wire go into what it disconnected from on the inverter or do I really need to go back to the glove box area for the H15 connector from the first test? The third and final test seems a little more straightforward, I think I can just have the red wire into the I10, black to ground.

So then what exactly would I replace if one or all of those 3 tests fail? I'm not sure how I would even replace the wires or connectors if that's the problem. if all 3 tests pass, it is the inverter that needs replaced according to the repair manual which seems easier at this point but I don't want to get ahead of myself.

Help is greatly appreciated especially on that clarification for the 2nd test needing the H15 tested as well as the I10, I just can't figure out which or where the H15 part of that test is.

 

the replacement bolts seem to have been the culprit for my P0a63 sub 302 error code. the fix is a junk yard story in part but I have completed many uber eats quests with no dash light errors since I made sure to have the exact toyota parts esp. for those two bolts that were stripped on mine on the outside of the inverter for the mg2 connector; those two bolts need to be the right size to fit into the limited space but not even short a few threads like mine where.