Gen I 2003 P3125 best course for diagnosis

Hi. I will try and skip the background and get to the point. I bought a 1st gen prius 2003 a couple months ago and it is throwing a P3125 code, triangle dash, etc. and dropping the transmission into what i gather is "safe" mode, such that it will not drive but enough to limp off the road. I know that to be the inverter code, and that sub codes help, which I do not have, and the P3125 could mean problems elsewhere and not specifically with the inverter. There are no other codes, other than a P0300 general misfire which I take as unrelated.

I had thought it may be the transaxle. It has the shudder when starting from a stop, and I know the winding short is a common problem. I've read up on the fix, luscious garage and all, called around, but when I have run the meg test on the wiring it does not give the results that would indicate a wire meltdown.

The other common problem with the coolant for the inverter looks to be alright also. There is coolant flow. The pump appears to be working according to my understanding of how to check that.

A bit of history, the car is in great shape in and out, 124k, garage kept, maintained regularly at Toyota. From looking at the records, apparently the previous owner took it into Toyota one day with the P3125 problem, Toyota suggested replacing inverter, and the owner traded it in instead. The prius was put to auction, a used car dealer had it for sale and I picked it up.

I put about 80 miles on it test driving with no issues. Then put 300 miles on it in one day driving it to my place. Next day tried to drive and had the parking brake on. It threw the triangle and went into transaxle safe mode. I took the brake off, turned the car off, let it sit a couple minutes, turned back on and was able to drive it without issue, but only drove it a short distance. The next morning I believe the triangle and dash were clear, and I drove it another short distance. I brought a trailer to tow it home and when moving it to put on the trailer, it had the same issues. Once I got it home I was checking the parking brake. It appeared the parking brake was getting caught on it way up after being released, so I thought maybe the car was reading the brake as being "on" and was throwing it into safe mode. I fixed the pieces that appeared to be blocking the brake from "releasing" and was able to drive it for about three weeks without issue. It started having the same problem, so I have since let it sit while I have tried to figure out what is wrong.

So after all that, I guess my question is what would be the best course to take to diagnose the problem? And if there is a chance the system could be reading the brake as being "on" and throwing it into that safe mode? Each time this happens, the brake light on the dash will also come on along with the triangle, and engine light. I have a code reader (not prius aware), and it only reports the p3125. I know I can pick up a used inverter to swap, which is not too difficult, but didn't want to just start throwing parts at it. It would be great, though, if it were just that and not the transaxle. And I did not want to have a mechanic throwing parts at it either.

I have searched this forum and other forums to come up with ideas, but thought I would try asking outright. Specifically if anyone has heard of that potential "brake" issue I mentioned. Any help is appreciated.

Thanks,
jjv

 

Thanks Patrick. So basically, the sub codes would be worth the look? Will the scan gauge do the job for me? Is it one of the better ones to get? I figured I would need to get one anyway. I will take a look at my notes on the readers. I think SG is supposed to do the job and is less expensive. Don't mind having Toyota read it, but based on what I remember, it seems that cost would be better served putting towards my own prius aware scanner. I had just bought a nice one prior to the Prius, the Innova ScanTool 3160, and was annoyed at having to shell out for another. So yes, the P3125 is confirmed, if I am understanding you correctly. I will check into the scan gauge and pick it up unless I hear otherwise. Thanks.

 

Thanks for the replies, everyone. I do like the help. Chap, I'll take a look at what you mention. And Bob, I read through one of your posts in the past talking about the scanners and remember mention of the miniVCI. I will go back and read up. If I don't figure it out, I'll just have Toyota pull 'em.

And I am not opposed to experimenting with fixes, if that is what it comes to. If it comes to changing out the stator, inverter, and such, I'll do it. Just wanted to confirm whether I'd be able to determine with some level of certainty about the problem before doing so.

Thanks again. I will post what I come up with.

jjv

 

Thanks for the ideas. And I apologize for being offline for so long. Been messing around with a house buy, was pressed for time, and had to sideline this for the time being. SageBrush, the coolant and pump had appeared to be working properly, unless you were referring to an additional valve issue beyond the problems some have had with the pump. I will take a look for that valve.

Yotatoter, I don't think I've actually had the lid off that inverter, which I probably should have done long ago. Will poke around.

Thanks for the suggestions.

 

Oh, and any suggestions on a reliable place to pick up a used inverter? I came across a reference in a blog a while back, but will have to check and see if I made note of it.

 

Thanks guys. That is my opinion too. The Toyota dealership service history of the car shows that the dealer recommended replacing the inverter in the past, but the person just traded it in instead. I've heard stories of shops just replacing one thing after another, but I'm sure it's the bad that will be posted and that most servicers were competent. I'll be able to take a better look at it this weekend, but this may take me awhile to resolve as I find the time, and have to order and wait for parts. Thanks for the help and suggestions.

 

Lueung,

Thanks for posting. Assuming you get this reply! Sorry to be offline for so long. I had to wait for the miniVCI reader/software to mail from across the ocean. Then when I went to fire the Prius up to run the miniVCI, all the display lights went haywire and everything shut down. So my problems are compounding. I had had enough and set it aside for awhile. Turned out to be the 12v battery. It was new as of 3/13, but it will no longer hold a charge. The new 12v gets the displays working again, but now it will not go into "Ready" mode. It won't crank. I realize the 12v simply powers the computers and the main battery powers the car/startup. Ran the miniVCI and it is giving me the main battery codes p3000/sub389 and p3030. Been trying to find and read about the fix for those.

So now my problem is to get the main battery functional, if possible, just to be able to see about driving the car to run the miniVCIto get the other codes that were my original problem, which have now cleared b/c of the 12v issue. Or maybe the p3125 was a generic code thrown for the battery problem codes I now show on the miniVCI, b/c the reader I had been using before was not prius aware. I don't know. And the readings i am getting for my main battery block voltages don't look good. They are very low.

Once i get past this current issue, i can rely on your post and see what i get. It would be great if i had the same (assuming I don't have a battery problem also). Your docs are very useful. Thanks for letting me know. I may have found a mechanic who can check it out.

Also, I don't know about "calibration" codes, but the miniVCI readout does currently list the following:

Engine and ECT
14705401
14705402

Hybrid Control
899834706101
899814702007
899814702008
899814702009
899814702005

Same as yours, except for the two. But again, i am not able to currently run the miniVCI while running or driving the car to recreate the previous problem, so i am unsure how these are related or their purpose.

The miniVCI also currently lists C1259 and C1551, but i don't put much emphasis on those. Presume are by-products and probably not relevant, or they were related to the 12v.

I am assuming you replaced the inverter. Did you do it yourself? Used or new, where, and cost?

I'll let you know what i find out. As you can see, it might take some time, although I am concerned about letting this linger and just making it worse.

Thanks,
jon

 

Hi. I used XP. Didn't try anything else, so not sure about alternatives. I thought I also read about needing XP. Sorry i can't be of more help.

 

If anyone gets this, your insight and advice is welcome. I know I am sporadic on this thread, but I finally took the Prius to the shop. I never did so before b/c I didn't know of a good knowledgeable Prius shop to take it to. Still don't. Not sure about these guys. They just recommended the whole new battery setup; harness, ecu and such. Over $4k. I don't think they did anything I hadn't done, which was hook up the techstream. They didn't even open the trunk to check out the battery or drill down a diagnosis. Maybe it just needs a new ecu, or busbar and harness. They wouldn't know b/c I don't believe they checked.

In any case, I have attached the techstream reports I had already run myself. One is the original from 9/22. They car had been running, but just when I got the techstream hooked up, the car decided to die (12v was bad) and would never go back into "ready" mode, even with a new 12v. So I do not have a report from when the car was running, and I subsequently had the 12v disconnected, so I am not sure what codes I may have erased that I wouldn't know about without the car being able to run and drive. And I was new to the software, so I am not sure if the 9/22 had all of the possible diagnostic options run. The 11/5 report should be complete.

9/22 had P3000/389
11/5 had P3000/389 & 123 and P3030

Voltages in the blocks were low 9/22 and even lower 11/5, but i've heard those can be misleading.

Is it indicative of just needing to replace the entire set; battery, harness, ecu? Or is this where the manual needs to be used to drill down and attempt to replace specific components? The shop doesn't seem to have attempted this.

I'm going through the trouble of asking b/c I'm not so sure the car is worth me putting more money into. Again, I just got it this past spring and was only able to drive it for a month. Cut my losses now. It is in great shape otherwise. Like new interior/exterior. Drives smooth. Was getting 54mpg. 63 my first highway trip.

And do I need the car driving to be able to determine if there are any trouble codes for the inverter and such? My fear is to fix the battery to get it driving only to find out the inverter is also bad, and such.

Has anyone had their battery recharged at the dealer? Frankenstein machine? Maybe do that to get it running to test out anything else that may need the car driving to be tested?

Thanks for any help.
JJ

oh, and i didn't mention the other codes b/c i didn't figure them to be relevant