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My mother’s Toyota RAV4 developed a terrible screeching noise out of nowhere starting up in the driveway. Right away, there was a strong electrical smell under the hood. Under load, with the engine running, the meter was showing 12 volts and bouncing around somewhat. With the car off, the battery was 12.5V. I removed the serpentine belt and rotated the alternator by hand, and there was a scraping noise. So then I reconnected the battery and started the engine without the belt and the awful noise was gone.
This is where I’m really pissed off at myself. I forgot to disconnect the battery again when removing the old alternator, and, you guessed it, blew the 140 amp fusible link block next to the battery. $55 part from Toyota and none in stock locally.
The good news is the car starts fine with the new alternator installed, and the screeching noise is gone. The bad news is the meter was again showing 12 volts with the engine running and under load. I’m hoping this is because of the blown fusible link and will correct itself when I replace the fuse link.
Do alternators fail electrically at the same time a mechanical fault develops? I’ve never had this happen, so I’m not sure. All of my past alternator failures were “silent” if you know what I mean.
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[quote=”desertdude” post=139464]The good news is the car starts fine with the new alternator installed, and the screeching noise is gone. The bad news is the meter was again showing 12 volts with the engine running and under load. I’m hoping this is because of the blown fusible link and will correct itself when I replace the fuse link.[/quote]
It is. Without that fuse the electricity generated by the alternator cannot make it to the battery. The drop in voltage you are seeing with the engine running is normal when the alternator is disconnected, which is essentially what you have while missing that fuse.Do alternators fail electrically at the same time a mechanical fault develops? I’ve never had this happen, so I’m not sure. All of my past alternator failures were “silent” if you know what I mean.
No, not really, but coincidences happen. I’ve replaced bad bearings on alternators where the unit still operated fine electrically. I’ve also replaced alternators that were not working electrically but still had good bearings.
Got everything back together. The replacement fusible link block saved the day. Alternator purs nicely at 14.1 volts.
The “hard” part was dealing with the low idle afterwards. Never seen an ECU struggle so much to re-learn everything, especially after several trips — it was nearly undriveable. But cleaning the MAF sensor, PCV valve, and throttle body cured it.
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