Battery Draining at idle in Drive and Reverse
#1
Battery Draining at idle in Drive and Reverse
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.
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.
Last edited by JKBHEAT; 04-14-11 at 04:23 PM.
#5
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.
#6
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.
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topgun129
ES - 1st to 4th Gen (1990-2006)
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08-03-13 10:02 AM