'02 Prius, Not starting, P3125 Code

Jerry - my e-mail is [email protected] for manuals

 

Engine revving up as fault code comes up sounds like inverter problem. If inverter can’t send power from MG1 to anywhere then there isn’t anything to hold engine rpm down.

 

The flash makes it very difficult to read all the values. I think Windows has a screen capture technique that would have eliminated the camera shot of the screen. At work, I use "print screen" and then paste the buffer into 'paint.' No camera and a good capture. To read the screen photo, I have to load it into a photo editor and take sections for image analysis.

Still, this is what I found significant in the first screen:

• SOC ~21% :: Holy crap! The traction battery is severely discharged. The normal low limit is 40%
• IW -2 A :: The car electronics are being powered by the traction battery
• 12V battery is OK
• The shift sensor says it is "P" but it acts as if it were in "N" or something really bad is going on.

If you ever get the engine to run again, try shifting into any other gear except "N" while watching for a charge going on the traction battery. If you see evidence of charge, hold it for at least 10 minutes to get the traction battery back up.

The second photo shows SOC 24% which is consistent with battery rest recovery.

Ok, I'll go out to my car and use the safety interlock to induce a code and subcode. Then I'll make some screen shots that will show what we're looking for.

LATE: Subcode 345 from the freeze frame -> "Abnormal current value of generator"

"If the information code 344 or 345 is output, check if other DTC or information codes are recorded. If they are recorded, check and repair those codes first.
If the information code 344 or 345 alone is record, replace the converter & inverter assembly."

Bob Wilson

 

Your battery shows a state of charge of 20%

When I have had a state of charge that low I have used my charger to bring the state of charge up to 60% before I ask the car to take over charging. The inverter may still be the problem but it also may be the voltage to the inverter is so low from the battery it is causing the inverter code to appear. The inverter code 3125 has many sub codes that may shed more light on the problem. Maybe Bob knows where the sub codes appear in techstream windows. Swapping hv batteries may be the answer lf his other car is a 2001 to 2003 prius. That way his other car could bring the low battery up to charge, if it would not start or charge the low battery then he would know it is the battery and not the inverter. It would take a few hours to do that and leave him temporarilly without a car to drive.

 

No problem but you can see how the reflection makes it . . . difficult. As for the screen shot, perhaps a PC wizard might have a suggestion. I run Virtual PC on a Mac and my screen shots are a lot easier.

Without power, the car would not run but in this case: (1) some charge to spin up the engine, and (2) DC-to-DC converter applying charge to the 12V circuit. The 12V circuit looks good!

Cycling through the shifter positions is just a wild-nice person guess that maybe you can trick it into charging the battery. If it works, GOOD. If not, nothing but one more engine start event for a traction battery going only one way, weaker.

Only you can value your time.

Now over in the Yahoogroup Prius Technical Stuff, some have described using light bulb as a current limiting resistor and a rectifier (aka., Radio Shack) as a 'Hill Billy' traction battery charger. But I would recommend talking with Eric as his solution is probably a lot less risky.

Bob Wilson

 

The subcode is in the freeze frame, 345.

We know three failed starts sets an inhibit code but disconnecting the 12V clears it. You didn't know and that is just part of the Prius lore.

I do not know how low the traction battery can go before it won't try to start the car. But at this point what do you have to risk?

Disconnect the 12V one last time; reconnect, and; try to start. If the engine runs, try cycling through the shifter positions. If you see it charge, stop and recharge the traction battery. If not, you'll have a decision to make. Leave the wife's car alone.

Bob Wilson

 

The toyota manual says with subcode 345 replace the inverter assembly, since you have a spare inverter change it out and see if this corrects the problem. Be interesting to find out how this all ends --- like a mystery theatre with everyone making a guess who committed the crime. We are all amateurs (I think) who trying to help and giving our best guess as to the cause and correction of your problem and will learn from your experience once you get the car going. Please don't give up.

Roy from Canada

 

It only takes about 20 mins to remove the hv battery out of the car. There's YouTube videos on the process. You'll at least be able to test your hv battery first hand and eliminate it as the problem. However, I've had over 20 priuses with dead hv batteries and not one ever through a 3125 code. Every 3125 code I've had was a burnt transaxle.

 

So what happens when you hear this winding sound because I have that in my Prius when I decelerate?......I don't have any codes or a check engine light?

 

When the stator develops a short, it becomes a permanent, unregulated, heat source that proceeds to burn and short more windings. But other noises such as bearings and CVT joints can also make speed coupled sounds. For MG2, there are other diagnostic techniques:

1. ICE temp > MG1 temp > MG2 temp :: if MG2 temp is greater than MG1 or ICE temperature, it is failing.
2. Sample transaxle oil :: if black and smells burnt.

This was the last one I saw being removed.

Bob Wilson

 

@bwilson4web I get the same sound noted in the Youtube video above only when braking and it stops when the car stops.....Wouldn't that be considered as simple as a regenerative braking system sound ?

 

The speed and pitch relationship will be simular. However, a shorted stator can never be turned off and over time, it has substantially larger, unlimited current. Regenerative braking is managed by the power electronics and limited to avoid hurting the traction battery. It is often described as a 'humm' suggesting a substantial mechanical stress.

Bob Wilson

 

@bwilson4web .........Thank you Bob.....You are our Prius Icon....

 

The real icons were the first adopters in 2000-2005 who taught me. I just share what they pioneered. Folks like Doug, Hobbit, Davies, Patrick, and others who 'cracked the code.' I'm just glad to pass on what little I've learned from them.

Bob Wilson