Heya everyone -- great resources here, thank you all for sharing 2003 Prius, ~130k miles Shudders badly sometimes with foot-off-brake creep, and throws a red triangle code that can be reset repeatedly, but obviously the problem recurrs. If driven with a heavy foot (ie, no creep --- put in D and hit the pedal hard) the shudder is minimized/eliminated. Everything i have read/youtube indicates that this could be common MG2 problem. I have a parts car (bad HV battery) and of course the MG2 is available as Dorman 587-990 Points of confusion: -- Which HV connector, the flat one under ww wipers, or the round one at the front of the inverter is MG2? -- Should there be continuity between the phases at all? I've removed the round plug at the front (HV and 12v batteries disconnect ofc) and using a cheap megger it seems to have near infinite resistance to ground on all three phases. However, there is open continuity between all three phases using a regular meter and continuity tone/beep. This seems to be pretty wrong.
brief update --- because the HV plug has been out for a few weeks, wanted to make sure HV battery not discharged, so put the HV cabling and safety disconnect back and started it. Shudder a bit on startup, set the RPM higher twice and eventually settling at 1400. The cooling fans running as well, even though it's freezing. A red triangle and a new code: P3125 Inverter Malfunction previously, it already had these codes: C1259 HV System Regen Malfunction C1521 Motor C1522 Motor The screen display did show the battery bar as low -- like 20%? it's not precise. Nothing has been done except disconnect the HV cables from the interver to test with meters, and everything is/was reassembled. haven't tried resetting the codes yet, figure to run it a bit. It's warm (blue light off) and still running the fans pretty fast. I assume this is related to the errors/codes?
Didn't didn't these first gen's have the MG1 or MG2 problem seemingly a bit more than the generation too and others and was kind of like a known thing happened to quite a few people? I could be wrong I just remember seeing something about this quite a bit with the little 4 door sedan
You haven't shown us all the trouble codes yet. The new P3125 might only mean you goofed a little putting things back together. At least, I would go back and recheck that work before assuming it's something more. The codes you had before were two from the power steering (C1521 and C1522) indicating abnormal current in the steering motor circuit. The steering motor is built into the steering rack in gen 1 and the wiring runs back to the steering ECU behind the glove box. The C1259 is a code from the brake ECU, but it doesn't mean a problem with the brake system. It means the brake ECU was notified of a problem with the hybrid system. The presence of the C1259 code, plus your report that the red triangle lights up, both mean there were hybrid system trouble codes too, which you haven't reported here. Often people use scan tools that aren't able to communicate with all the ECUs in the car, and so they end up seeing only some of the trouble codes. You haven't listed any code here that would indicate any issue with MG1 or MG2. From here I can't say whether that means you have no MG1 or MG2 problems, or you do and there were codes about them but your scan tool didn't retrieve them. Or did you assume "motor" in the power steering codes meant the traction motors? As for testing MG1 and MG2, of course you want the megger to show insulation between all phases and ground. Phase to phase might very well give you a continuity beep. Consider the gen 1 uses a 274-volt battery and no boost converter, and can push 120 amps into a motor phase that way. So even scribbling on the back of an envelope there should be no surprise in seeing the winding resistance come out two ohms or less, down in the ballpark where you wonder how much of the resistance you're seeing is the winding and how much is your meter leads. Scribbling further into the corners of the envelope, I would bet the winding DC resistance is even lower than that, and in operation it's the AC reactance that matters more. So I wouldn't say anything about your test results so far would cause me any worry about MG1 or MG2. Edit: by the way, gen 1's P3125 code was a giant dumping ground for many many possible issues with the inverter or converter. Later generations have a bunch of different trouble codes. In gen 1 there's the one P3125 code with at least eighty (I'm not making this up) different INF codes. If you are not using a scan tool that shows you the INF code, there's really no knowing what this code is telling you about.
