Alternator Warning light

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Alternator Warning light

Postby Icedmunkie » Wed Sep 01, 2021 5:57 pm

I've got an MX5 1.8 NB engine in my Vauxhall Firenza, I have swapped the original ECU controlled alternator for an NA non ecu controlled version, however I can't get it work correctly with the Firenza clocks.

There are 3 wires on the alternator:
1) this is easy its the feed to the battery
2) Grey/white, if I earth this to the alternator the revs drop and the vehicle starts charging at a steady 14.6 volts
3) Grey wire, this appears to do nothing but I think is voltage sensing wire as it always has a nominal voltage between 0.27-.0.51 volts when running or not running

The Firenza ignition warning light, works if this is earthed and goes out once voltage is seen, however this won't work as both wires on the alternator have voltage regardless if the vehicle is running or not.

I've looked online and think I have worked out how to wire up the alternator to work but not with the ignition light. Has anybody else come across this with another vehicle and how was it solved.

I can provide various readings as required.

Thanks
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Re: Alternator Warning light

Postby brading » Sat Sep 04, 2021 10:30 pm

Can you post a picture of the alternator showing the terminals. Also the make and model of the alternator.
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Re: Alternator Warning light

Postby Icedmunkie » Wed Sep 08, 2021 1:03 pm

Hi,

I have taken this to my local alternator place who has changed the rectifier for me, I personally don't think it was needed as it would charge if i put a wire to earth but it still doesn't work.
I know the dash side is correct as if I earth it, it lights up but with the new system it still doesn't light up.

The make (i think is WAI) Model 13559N.
I have attached a list of alternative numbers in case that is easier.
Attachments
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Re: Alternator Warning light

Postby brading » Fri Sep 10, 2021 7:54 pm

I cannot find a diagram of which of terminals are for the sensor and which one is for the warning light. With alternator fitted on the car and the large terminal connected. With a multimeter check if you have 12v between just one one of the small terminals and the positive terminal of the battery.
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Re: Alternator Warning light

Postby jpsmit » Sat Sep 11, 2021 2:36 am

not sure if this is any use at all but, last fall I let the smoke out of the wiring on my MG - specifically I got a socket extension stuck against the live terminal on the alternator. I still wonder if the old alternator was OK but, I got another one anyway (GM Delco) - I wasn't getting anywhere until I discovered I had to excite the alternator. So I took it for drinks ... Ok not really but, it did need to be done, I can't remember all of what I did so, googled it. Here is a link but there are many youtube videos

https://www.delcoremy.com/the-latest/20 ... -the-field
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