Hi All, 

Hoping someone can help here. 

I've recently finished my 2GR swap. On the way down to Sydney the alternator died. I got a replacement and drove back to Brisbane
When I went to leave work yesterday, my alternator had once again died.

This is two in 3000kms~. Whilst they are both used, they worked with no problems until I started the car up on both occasions and suddenly was not charging. Another thing I noticed was that the battery gauge indicated less charge at idle but higher when on the motorway. It's not an accurate indication of voltage but it was enough to make a movement on the dash.

I am not necessarily looking for 2GR specific advice, any sort of input relating to what could cause this would be appreciated.

We have tested the three wires that go to the plug on the alternator. they all receive battery voltage. The light on the dash was working when we replaced the alternator. 

I'm at a loss to what it could be. I doubt it would be heat as other mr2 owners with this swap have had no problems so far. 

Any feedback is welcomed. 

Cheers,

-Eric

Battery OK?

Reddtarga
Battery OK?

Yes battery is ok and only 2 weeks old.

What are the 3 letters for the plug going into the alternator?

Only reason i ask is some arent necessarily meant to have 12v on them.

Has it failed in the same way this time - i.e. is the charge warning light no longer showing again?
 
Also what else has been spliced spliced into the 3x wires going to the alternator (what else is being supplied from the Alt sensing and Volt Gauage / Warning light fuses)?

What happened with the oxygen sensor wiring which melted over the exhaust and shorted out? I can't remember you mentioning whether that ever got fixed.

What was actually wrong with the alternators? The two that stopped working. Maybe get them inspected to see what the actual failure was? Could be an integrated regulator, internal diode, brushes, bearings etc
Do you have good grounding from the engine to frame and battery to the frame?

Diodes were fried from memory Nick.
 
There is obviously a issue here with as MCT mentioned wiring.
 
If you cannot figure it out easily id be buying a normal old school type alternator that bolts on roughly the same and being done with it.

Have a read of this webpage from about 1/2 way down where it talks about diode failure and also tests to perform.
http://www.aa1car.com/library/charging_checks.htm
 
Might help you locate the issue.
 

Wiring was checked and re-checked by a dozen different people at Wakefield and found to be OK. Inputs are all 12V from both the SW20 & Aurion wiring diagram. Only possible difference being PIN3 used for the 2AZ engine ECU alternator control, N/C for the 2GR and not present on the loom plug. It is possible the the loom plu and alternator plug were arse about, however the pin order was correct according to the 2GR diagram.

The regulator appeared to be toast as the charge lamp circuit was always open (normally closed to ground 'charge faulty' lamp, held open when alternator is operating correctly).

At least a universal alternator will be serviceable and easier to troubleshoot thanks the 2GR alternator.