kumiko44

iTrader: (1)

So I searched through the threads and none of them seem to have the exact same problem as me.

Friday afternoon my alt suddenly stopped charging. I only had about 10 minutes of warning before the car stopped running completely. Bought a new battery, threw on a new belt. Managed to get home. Car wouldn't go above 12v on the gauge. Yesterday, I took my brother to a dealer to pick up his new truck, car remained at 12v while in the city, but jumped up to 13~ on the highway (doing 100km, rpm was about 2500 I think? If that matters). Brother tested the alt, it was giving out 1-3v on idle.

Today, we put a new alt belt on (I noticed cracks in the one I'd put on friday afternoon, plus I had to put the waterpump belt back on) and fired him up. He sat at 13.5v while in high idle warm up, but after about 3-4 minutes of running it dropped back down to 12v.

I'm at a complete loss. Luckily I work for an auto parts place, so I've got a new alt coming in. But I'm wondering if anyone else has had this issue before? My current alt is only about 5 months old (replaced the bosch one I was using before with AC Delco --lifetime warranty on this bisch--) but the previous two alts both had overcharging issues (bosch sucks) so I'm not 100% sure that it's JUST the alt that's the issue.

Anyone have any insight to share with me? Currently pulling my hair out as this is my only means of transport (please don't make me take public transit T-T). Oh, car is not modified in any way, it's bone stock (it's auto, why would someone mod an auto amirite?). I do have a relay to keep my markers on (switch fried a couple years ago) but I really don't think that's the issue.

TIA!

kumiko44

iTrader: (1)

I got the new alt in, it didn't change anything. It's still jumping around like it's mimicing a jumping spider. I pulled off the relay just to see if that was indeed the issue, didn't help. My battery is fine, my alt runs the car if I take the posi terminal off... I'm lost. Is my only solution to take it to a mechanic?

AZOG

did you figure it out ?

mazdaverx713b

iTrader: (91)

She hasn't been online here on the forum in over a year so I'm not sure you'll get a response any time soon. But it would be good to know if the issue was resolved and what the cause was.

iosis

You should never take the power cable off the alternator while it's running on a car with an ecu. That's an old hot rod thing to do. You can send voltage spikes that can fry your computer.

I rebuild starters and alternators as my day job, it sounds like there is an issue somewhere in line with the power system. If anyone has issues like this with the alt cutting in and out, and it's not very old you have to be thorough and check every wire, relay, fuse, ground etc in line from the battery to the starter and alternator.

Oh and fyi AC Delco remans are mostly garbage that are assembled in Mexico, some of the offshore aftermarket units are better. I can't speak for every rebuild shop out there, but the work we do in mine is top notch, you're better off going to a rebuilding shop than a parts store.

Rotary Alkymist

Intermittent issues are "usually" wire related. A bad terminal or a half broken wire that connects because of vibration. Perhaps corrosion building up around the crimped part of the terminal.

FührerTüner

iTrader: (5)

This or maybe the diode in line with the exciter wire took a ****.