JKBHEAT

iTrader: (5)

So long story short, I think my Power steering wrecked my alternator (battery indicator flashing, bad stuff, etc. etc.). I replaced my alternator today with a re-manufactured unit (100% working) and everything seems to be fine (~14V with the car on).

I also just bought a voltmeter that can be used in the cigarette lighter to monitor battery/alternator functionality. As I observed it everything matched my prior test (12.6V w/ car off and ~14V w/ the car on). I then noticed that while stopped at a red light my battery voltage began to quickly drop from 14 to the low 12 range (like the alternator stopped working), as soon as I put my foot on the gas it went back up to around 14V.

I knew this was odd so I did more testing; here is some more info. The voltage only drops when the car is in drive or reverse and the brakes are depressed. I turned on the A/C and saw that it does not drain at all with the A/C on. This made me believe it was an idle rpm problem. I messed with the TPS sensor and with a higher idle (1k in park and 750k in drive) there was no drain. My regular idle is around 500-750k in park and drive. The only problem is that I cannot find a middle ground with the TPS sensor, it is either 1k (idles too high) with no drain or 600-700k (normal idle) with a drain at a full stop.

Does anybody else's SC do this? Any explanations/solutions? Is it a serious issue to have the battery/alternator drop to the low 12 or even high 11V at red lights (as in can it cause damage to the charging system)?

Thanks a ton!

Oh and lmk if anyone need some pointers on removing the alternator. I've done it twice in 1 month. And the second time I did it without jacking the car up or removing any other items from the car.

tl;dr: Just installed a reman'd (100% working) alternator; charging system is around 14V when rpms are over ~750 but when the rpms are around ~550 (completely warmed up and stopped) the voltage begins to quickly drop from 14V down to the around 12.00.

JKBHEAT

iTrader: (5)

Added a quick summary at the bottom. Hopefully that helps.

iwannadie

iTrader: (1)

Could be a long shot, hows the belt and tension? Could be the belt is slipping and at low RPM your not turning the alternator enough.

94LEXUS400

Seems like bad alternator...its reman so its possible get it replaced.

JKBHEAT

iTrader: (5)

I was thinking this as well. How would I know if the tension is off? The belt visually looks normal during operation but when off I can kind of push the belt down an inch or two (like it has little slack). But I'm pretty sure that the SC400 has an automatic tensioner and the gauge thats behind my tensioner is right in the middle.

I highly doubt that it's bad. I bought it from reputable local shop (w/ a 6 month warranty) that "only" deals with alternators and starters. I had them test my old one and the new one (which worked perfectly). I even had the new one tested at an autozone on the way home and it tested as new.

iwannadie

iTrader: (1)

I'm not familiar with the sc400 at all. I am sure you could search or check the FSM and get all the details on the belt tension. Again it's a long shot but at least it is something free and easy to check.