Hi everyone,

I had my car off the road for some time doing maintenance, updating, tidying up which included installing a new alternator (old one died).

Anyone who knows 100A alternators for MR2s knows how difficult they are to find and as my old one appeared to be an aftermarket unit, rebuilding it was problematic.

After finding and buying one from the USA (there's another story in that), I installed it.

Anyway, after waiting a long time to turn the key for the first time I knew immediately something wasn't right when I had the battery/cooling fan/cat converter warning lights illuminating when the car was running.

Here are the tests I did:

1) brand new battery with good terminals/connectors

2) tested battery with multimeter and getting no charge (~11.9v running)

3) Alternator belt is good and proper tension

4) checked relevant fuses (ECU-IG, ALT sencing etc and all good)

5) unplugge the round 3 pin plug from back of alternator and battery/cooling fan warning lights go out on dash

6) Unplug the 3 pin plug from alternator and with car ignition in ON position get voltage ~10.5-12v at the 3 pins

7) As per service manual, remove cable from B terminal and attach positive of ammeter to B post and negative to cable = get a reading of 0.21A (manual stipulates under 10A is correct).

8) Put voltmeter to B terminal and ground negative terminal getting a reading of 0.54V (this is bad, should be charging volts so 12v+)

9) As per service manual, conduct a full field test (grounding terminal F) at the rear of the alternator and test voltage output. It drops slightly from aforementioned 054v (indicative that regulator is not at fault I believe)

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Now I feel I/most others may reach the obvious/most likely conclusion but I'm after any advice from knowledgeable minds on other tests or strong opinions on what's at fault.

I look forward to some comments and a few less grey hairs at some point.

Thanks

When i saw this post it reminded me of when i bought my car previous owner told me that he had changed the alternator recently and the shop had trouble finding one so they ended up putting a toyota land cruiser alternator in it as it was close enough match apparently.
I haven't checked part number tho.

TonyMR2: thanks for the reply, don't quite appreciate the sentiment and while I could expand on some of the things you said, I won't.

Xmr2: very interesting you say that, I was actually really hopeful of finding information like that but from all my research I never found a conclusive "an alternator from XXXXX will fit and work in an MR2" and I simply didn't have the time/ability to play around with combinations. Looking at some photos the LC unit actually doesn't look that dissimilar other than possibly changing pulleys

MG MR2 - you don’t appreciate the info, then I will remove to ensure I don’t assist. Expand all you will, of your credentials and knowledge, continue on your path.

After trying like 50 times in the dark under the car i managed to take some shots of the serial numbers of my supposedly LC altenator.. Hope this can be helpful to someone

It''s a forum to assist each other, your original post came across quite angry and condescending from the onset

Legend Xmr2, I wasn't going to ask you to try because I know it's a pain, thanks very much for doing that

All good mate... Let us know if it is a LC altenator as i did quick google search and didn't find anything.

Could you purchase a used known working alternator from one of the MR2 wreckers in the country? Then either fit it as is or have it serviced/refreshed by auto sparky.

Yeah that's an option, the ones I have are oem cores I believe so I'm planning on having them bench tested and rebuilt if need be.

Xmr2 - does appear it's LC mate. Punch 'ATG312 alternator' in Google. That A-14 number which is then covered by 'void if removed' sticker (funnily enough) would confirm it. I think it's pretty interesting because in all my research/googling, I haven't seen anyone write about using different alternator which I found strange because that's pretty common in older cars with hard to replace items