There is a misprint in the mr2 wiring manual I have here that mislabeled 2 of the wires , it is corrected later in the book but you have to be vigilante to pick it up, could that be the issue?

fredhoon
Has it failed in the same way this time - i.e. is the charge warning light no longer showing again?

In my haste I didnt look at the charge light, but I will be inspecting this over the weekend. the car was starting to stall and hard to start.
 

MCT_MR2
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.

L, BATT, ALT-S. The fourth pin on the plug is blanked from factory but this is generally for ECU control over the alternator
 

robk
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.

For the moment I have the sensor disconnected and the wiring has been cut back and taped up. its running super rich because of this but it got me home from sydney.
 

TomsMR2
There is a misprint in the mr2 wiring manual I have here that mislabeled 2 of the wires , it is corrected later in the book but you have to be vigilante to pick it up, could that be the issue?

Can you give me some more info on this Tom? Thankyou

Update: I found out the alternator that the wreckers sold me was a RAV4 one, which is ECU controlled. They told me at the time that "this will work with your engine"

I'm going to have both alternators inspected and test to find out what caused the issue and if it was due to ECU control being present on both alternators but not used.

Craig (Scope) has suggested some scenarios which could have caused the issued:
1. Resistance in wiring or not enough grounding wires.
2. Dirty signal coming into the alternator which is spiking and blowing the reg.
3. Some ECU controlled alternators have the ability to go into "shutdown" mode when there is an issue with the signal coming into the alternator. This can be disabled by removing all power to the alternator and leaving it to sit for a while.

Worst case scenario I will be retro fitting a much simpler alternator but I would rather retain the standard one
 

Craig came to have a look at the car today. With the oscilloscope we measured 22v spikes on the coils power wire which was filtering through to the 12v supply in the engine bay.

Craigs going to do some investigating on an aurion and see what he can turn up. It would deffinetly suggest why the regulator has blown

I'm curious.
 
Is it possible to run the MR2 Alternator off the 2GR engine and have the good ol' solenoid control still working, or does the 2GR computer insist on regulating the voltage itself?

MCT_MR2
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.

yea true. most alternators i've worked with and wired up have battery volts on one pin in combo with charge wire to battery), 12 volt ignition on 2nd and the exciter (dash light) on the 3rd. 
 
hope you sort it out Eric. Possible to just run a aftermarket bosch universal alt?  wired up correctly with it's own circuit will do it's thing.