Please help! 2002 prius P3125 inf 304&307

Hi everyone! Here is my story...

I bought a 2002 prius knowing it wasn't running. The seller told me it should just need a new HV battery, but he wasn't sure. I successfully rebuilt the battery using modules from gen2 batteries.

I was able to start the car after I fixed the battery (MG1 turned the engine and the engine started). It yielded the codes p3100 and p3125... which is the HV ECU and Inverter. The vehicle would only crawl about 2-4 mph on a flat surface and the 12v battery wouldn't charge. I replaced the HV ECU and the p3100 code dissapeared. I then replaced the inverter. The inverter did fix my battery charge problem... but not the 'crawling' car problem. I thoroughly tested the wire harness between the HV ECU and inverter as the p3125 diagnostic charts suggested.

Still with no luck, I towed the car to toyota so they could pull the INF codes with their nifty $12k scanner. The codes were p3125: inf 304 and 307... which both point to motor gates and current values.

304: "Motor gate shut-down signal line malfunction"
307: "Motor current value malfunction"

I'm not a 100% sure what these mean or what the problem is pointing to.

Its also interesting to note that a p3000 code came up while at toyota. INF 388, which says the battery drained while the car is in neutral.

This all sounds to me like a problem with MG2 since the vehicle only crawls and the 'motor current' issue... but there isn't any DTCs pointing to the transaxle.

Any thoughts or suggestions would be appreciated!

The dealer's diagnostic was to replace the battery... but I think that is BS. I should also note that I'm a complete novice... I have never worked with a hybrid prior to this prius, nor have I done any diagnostics on a vehicle before this one.

Thanks Everyone!
I appreciate your help!

 

I used modules from two wrecked 05's. I used all the modules from one that had 38k miles and the other 10 modules can from one of unknown mileage... but was estimated under 100k.

Thanks!

 

Thanks for the suggestion! I did do a little fooling with the harness before I took it to toyota. None of the harness between the inverter and HV ECU had and ground shorts and none of the wires had continuity between them. I guess a next good step would be to check the resistance in the wire. All of the connections seem snug.. I guess I'll try checking continuity on both sides of the connecter for the mentioned pin.

Thanks!

 

The screen does show the battery charging. The code that accompanied p3000 just said that the battery was draining while in neutral. The battery does not drain while the car is off.

I have a little OBDII scanner and was able to clear the code, but It comes back as soon as I try to move the car.

 

Thanks again everyone for your help! Sorry I havn't been responding with any progress or ideas of my own... I've been in some very involved training the last four weeks far from home and havn't had access to a place to work on the prius outside of a hotel parking lot. I am now in Atlanta... no longer in florida for a new job... I will hopefully have some updates in another week or so.

 

Thanks for the suggestions. I checked the referenced wire. It is not grounding out. It reads between 6-7v while in the "ON" position and about 7-8v while the engine is running. I can give more exact voltages if needed (didn't write them down). I checked these voltages at both ends. I checked the resistance between both sides of the connector and didn't see any resistance so the connectors on the inverter side are good.

I'm guessing the diagnostics are pointing to the inverter/converter assembly if the wire harness checks. I'm guessing "motor gate" is referencing an assembly inside the converter. Is the "motor current inverter sensor" located inside the inverter or somewhere in the transaxle?

Its strange that I would have two inverter assemblies with the same part# have exactly the same problem. (I didn't get any inf. codes for the first inverter, but the symptoms are the same): Tops out at about 9mph in a level parking lot after about minute. (almost non-existant acceleration)

 

I did check the connector for any missing/bent pins and looked specifically at position 13. I replaced the HV ECU a while ago because the car was generating a dtc related to it. I did jump the OBDII connector to put it in diagnostic mode to get the ECUs to talk to each other.

 

Thanks for all the great info. I'm still pretty novice when it comes to this and I'll still a little confused. What would be my next logical step? I wouldn't know how to interperet the readings on the scope if I did get one. Does anyone know of any independant Prius shops in Atlanta?

 

I did try this already... none of the wires have continuity to any other wire.

 

I checked against every wire within the harness going to the inverter.

 

My intuition suggests that the inverter is bad. I'm thinking the common symptoms between the two inverters is probably just the failsafe. Toyota told me the problem was the battery, but I rebuilt it two weeks previous with gen2 modules... I honestly think the dealership was just trying to sell me things because it was modified. I didn't get any error codes related to the battery other than the one that states the battery drained while in neutral... but thats because the dealership was running the car in neutral for an hour with headlights on and A/C full blast (doesn't charge traction battery in neutral, but dc-dc converter still charges 12v= drain.)

I'm seeking professional help through some certified techs on justanswers.com but they seem stumped with-out hands on. Toyota wont touch it until I replace the battery... so I'm trying to find independant shops in Atlanta.

I think my next step will be a third inverter.