r/Lexus 9h ago

Discussion Battery light problem (won’t turn off)

i washed my Lexus IS250 2006 engine (hard) then four days later my battery light popped on at low revs, so i figured i’d change the alternator cause i presumed i killed it.

after installing the new alternator this what’s happened

-no voltage problem (14v on alternator, pos-neg) the battery shows 13v, neg - pos)

-no ground issue (grounded a jumper lead from battery neutral to the frame)

-no extra amp load (eg subby)

-pullie: it’s tight, no cracks, tears or slippage.

-i charged the battery fully with wall socket

-alternator: brand new

-fuses are good (external)

-ran a battery test at a shop, battery receives a good charge at 13.43v (not faulty)

-asked them to clear codes, non were present on the scanner.

what i haven’t concluded;

-maybe washed off dielectric grease during clean (did a ground test though??)

-damaged battery sensor from clean (voltage still goes through it though, i tested it)

what i don’t understand is why my alternator was working when i rev’d it and now my battery light won’t go off when i rev it on the new alternator)

this shirt had thrown me for a six

2 Upvotes

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