Help with fault code and noise p0a78

[Lwerewolf]

p0a78 was what I got a day prior to the inverter's IPM (igbt power module) blowing up - granted, I decided that "it's time to stress test it", and I did 😛

Given that RHD inverter assemblies are (or at least very much used to be) rather cheap and plentiful - I'd get one from a crown hybrid (gws204, RHD-only).

The IPM isn't available separately, and it's of the classic type (not sintered, not dual-side cooled/sandwiched/etc - basically solder layer degrades, heat transfer degrades, etc). It's not the thermal grease, I've tried.

edit:

my EV noises became a lot more apparent when I swapped my rear diff for a US/JDM 3.769 one (due to the higher mg2 rpm at low speeds when you can really hear it - ESPECIALLY when it's warmed up and AC & vented seats & music are all off), but absolutely nothing like this - I don't think my phone will be able to pick them up.

You might want to check/log inverter temps (amongst other things) with hybridassistant.

[Sean84]

2 hours ago, Lwerewolf said:

p0a78 was what I got a day prior to the inverter's IPM (igbt power module) blowing up - granted, I decided that "it's time to stress test it", and I did 😛

Given that RHD inverter assemblies are (or at least very much used to be) rather cheap and plentiful - I'd get one from a crown hybrid (gws204, RHD-only).

The IPM isn't available separately, and it's of the classic type (not sintered, not dual-side cooled/sandwiched/etc - basically solder layer degrades, heat transfer degrades, etc). It's not the thermal grease, I've tried.

edit:

my EV noises became a lot more apparent when I swapped my rear diff for a US/JDM 3.769 one (due to the higher mg2 rpm at low speeds when you can really hear it - ESPECIALLY when it's warmed up and AC & vented seats & music are all off), but absolutely nothing like this - I don't think my phone will be able to pick them up.

You might want to check/log inverter temps (amongst other things) with hybridassistant.

Hey man thanks for input. Yes this sounds loud when it's bad. I also got code P0A90 - 251. 

What really strikes me most odd is this. Today for instance I've drove about 3 hours and lots of miles, urban and rural. Not a single issue, drive like a dream. Then out of no where with no obvious pattern of causing fault it starts with the whining noise from the transmission. It's so intermittent. How can a mechanical break down be faultless most of the time? Electronic faults are more prone to being intermittent. However with the physical problems and the codes, all professionals suggested the transmission over the inverter. But then when I get the worst physical fault I wonder how it can be like that and then be fine. Let me explain, often when I get the fault I will pull up, put in park, wait ten seconds, then turn off the the car. When the engine shuts down, the transmission shakes down to no more revolutions and shakes the car like a badly balanced washing machine. It's extraordinary to feel such a problem then it be fine. It looks like the previous owner may have swapped inverter already as there's proof of tampering up there. I guess I'm gonna have to bite the bullet? Just answer tech gave me lots of info to follow. But judging by fact it's mostly ok i don't think the tests will show me much. All detail testing, testing pins for voltage, resistance etc 

[Mr Vlad]

Ahhhhh evidence of tampering up there eh? So something has made you recall that. You should investigate that and probably replace the invertor. 

You should know just because an electrical item has been replaced, doesn't mean it was replaced with a true new tested one does it? More like a used invertor from a scrapper fitted. 

I've used many many parts from scrappers in my time. Have to say that 40% of them weren't up to scratch. 

[Sean84]

29 minutes ago, Mr Vlad said:

Ahhhhh evidence of tampering up there eh? So something has made you recall that. You should investigate that and probably replace the invertor. 

You should know just because an electrical item has been replaced, doesn't mean it was replaced with a true new tested one does it? More like a used invertor from a scrapper fitted. 

I've used many many parts from scrappers in my time. Have to say that 40% of them weren't up to scratch. 

Well yes I would on most occasions absolutely agree with what you say. But am draw away from that usuall thought because of advice from several different professionals based on the codes and some of the symptoms i explained, and also how sever the 'off balance motor' feels, on the odd rare occasion as described above. But you've just said exactly what I was thinking, so now, being the cheapest option, I'll see what I can pick up tomorrow and try get fitted over the weekend if I'm lucky. I'll certainly keep you posted. Thanks Mr Vlad your opinion 

[Mr Vlad]

Hey Sean. I'm no professional But I'm a true engineer tho not qualified. I seek solutions for everyday problems. That's what a true engineer is. No qualifications needed, just an effing good common sence head.

I have a respect for you because you are getting your hands dirty trying to get to the bottom of your cars issues. Bravo to you m8 👏👍 and you're welcome 

[Sean84]

20 minutes ago, Mr Vlad said:

Hey Sean. I'm no professional But I'm a true engineer tho not qualified. I seek solutions for everyday problems. That's what a true engineer is. No qualifications needed, just an effing good common sence head.

I have a respect for you because you are getting your hands dirty trying to get to the bottom of your cars issues. Bravo to you m8 👏👍 and you're welcome 

Thanks very much buddy. Sounds like we aren't too different. Sometimes fixing something isn't good enough without knowing exactly what's going on 🤣 it's as much a hobby as anything else. Always keeping occupied learning things. Especially things that scare most people off lol. 

I self taught micro electronics, diagnosing and repairing microscopic surface mount components on phone pcb and laptops from all sorts of damage and problems. I'd spent hours and sleepless nights researching and learning. It all paid off. Once I learnt and found myself most capable i tend to move on to the next challenge, here I find myself with the hybrid learning 😁

[Lwerewolf]

Well...

DTC No.	Code INF	DTC Detection Condition	Faulty area
P0A90	251	Reduced magnetic field strength of the electric motor or phase short circuit	Hybrid transmission assembly

That said:

DTC No.	Relevant diagnostics
P0A1A (all INF codes), P0A1B (all INF codes)	Malfunction in the MG ECU circuit
P0A1D (all INF codes)	Malfunction in the hybrid system ECU circuit
P0A3F-243, P0A40-500, P0A41-245	Motor resolver circuit
P0A4B-253, P0A4C-513, P0A4D-255	Generator resolver circuit
P0A51-174	Malfunction in the MG ECU circuit
P0A60 (all INF codes), P0A63 (all INF codes)	Motor Current Sensor Circuit
P0A72 (all INF codes), P0A75 (all INF codes)	Generator current sensor circuit
P0A78-306, 510, 586, 266, 267, 523	Motor inverter malfunction (n.b. me - motor means MG2)
P0A7A-344, 522	Generator inverter fault
P0A90-509	Motor system malfunction
P0A92-521	Generator system malfunction
P0A94-585, 587, 589, 590	Boost Converter Circuit
P0AA6 (all INF codes), P3004-132	High voltage system
P3233-750	Hybrid system valve lock wiring faulty

NOTE:

P0A90-251 may be set due to a malfunction that also causes the DTCs listed in the table above to be output. In this case, first troubleshoot the issued DTCs listed in the table above. Then perform a test to try to reproduce the faults and ensure that no DTCs are output.

First things first - log the inverter temps. Hybridassistant can log to a csv file, the "inverter temp" is the highest of either the MG1 or MG2 inverter temps. If it spikes wildly - there's a very high likelihood that the inverter has deteriorated to the point of being very noticeable like that - so I'd start with swapping said inverter. I'd too wager on it being at fault given how sudden and intermittent the issue seems to be. It's very likely that you're just a smooth/sensible/mature/whateveryouwannacallit driver - most cases of blown inverters aren't preceded by a p0a78, but then again - it's a sin not to use these cars' acceleration once in awhile... and some people tend to be holier than thou 😄 😄 😄

If you want to go down the rabbit hole - have fun