Blown Fusible Link

[Patrick0525]

Recently, my colleagues 2012 Toyota Matrix 2.4L lost electric power steering and would not re-start upon arriving at home. He replaced the alternator and still it remain non-startable until diagnosed and by restoring the fusible link near the fuse box.
The alternator shorted-out. He also noticed that the alternator output current post was slightly loose.
What are the possible causes of the short? Are the stator, rotor, copper slip rings damaged?
He returned the damaged alternator to Autozone as core.

 

[Trav]

If it blew a fusible link it was making power but shorted, I am thinking probably at the rectifier with that loose post shorted to case ground.

 

[Patrick0525]

Originally Posted by Trav
If it blew a fusible link it was making power but shorted, I am thinking probably at the rectifier with that loose post shorted to case ground.


Yes, the Matrix was working fine the day before. Sounds plausible a rectifier (diode ??) shorted to case ground.

 

[Trav]

There are diodes in the rectifier assembly as well as a diode trio mounted away from it. This will explain it better.

https://www.carparts.com/classroom/charging.htm

 

[eljefino]

I had a y2k camry with blown fusible link-- came that way from previous owner.

I think they had a bad alternator, changed it, but left the battery connected, and battery power backfed through the fuse and blew when the output lug shorted against a ground.

A toyota with a main fusible link blown will typically run, but give you zero creature comforts. I couldn't move the driver's seat, roll down any windows, few gauges, etc.

IIRC you aren't supposed to gun down alt studs with too much torque or they'll break free internally and then not work or barely work. There's sometimes a flat on the stud for you to put a back-up wrench when tightening.

 

[andyd]

Veeeerrrrryy interesting. A potentially useful factoid of Toyota lore.. I had a Grand Wag pop a fusible link. I had to hot wire the coil and jump the contacts on the starter to start the engine. Then nothing worked but the engine . At home I swapped in a link from my parts jeep. I may have taped up a bare wire between relay and starter too. I learned to be careful about threaded electrical connections in my usual fashion, the hard way.

 

[GZRider]

Is disconnecting the battery and allowing the car to discharge before working on the electrical system/putting in an alternator no longer a thing?

 

[Trav]

You should whenever you disconnect or connect live power wires.

 

[mk378]

It's really important when R&R alternator, since the big output wire is always live and shorting it to ground would burn out something significant.