pulsing lights - alternator

My car became a disco, every light was pulsing. Looks like I need another new alternator.

Output voltage seems way too high at about 15v at the alternator output terminal.



There's about a volt of AC ripple, which is visible in the lights and no need for an oscilloscope to see. There seems to be quite a bit of noise on the output as well.



So much for ACDelco professional. That alternator is only about 4 years old, maybe has 3k miles on it at best. I've got a Remy unit inbound I got a clearance deal on, we'll see how that works out.

Just get a parts store lifetime warranty alt. Never pay for one again.

Wish I had an o-scope. That's my next purchase.

I don't usually have much faith in the parts-chain electrical stuff, but you're right- I suppose their warranty says something about their own faith in what they're doing!

And even if it does die - it's 15 minutes to swap and free.

Worth its weight in gold for starters and alternators.

So to kind of wrap this up and share a story, which is what I seem to be around here for...

"warehouse deal" alternator arrives today. It's shot. Looks like it took a hard hit and the fan/pulley assembly got pushed into the case. Video below, it's cringeworthy.

screechy!

The Remy and ACDelco units are clearly identical. Realizing that I could swap the back cases and merge the new Remy electronics into the older ACDelco mechanicals in literally a few minutes, I did exactly that.

14.5V out the back terminal now, 50mv AC ripple instead of 500mv, and headlight disco has ended.

I complained about the problem and they gave me a partial refund making the now bad Remy unit a $40 investment. Not bad for a DIY "rebuild", right? I'll keep on the shelf for when I need it as a $40 core on a store-bought unit 4 years from now.