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Toyota Yaris battery light after alternator replaced


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White Trash CVP
User

Dec 1, 2020, 6:27 AM

Post #1 of 5 (121 views)
Toyota Yaris battery light after alternator replaced Sign In

2007 Yaris, 1.5L 5 speed - ~200K.

Just replaced the alternator with a reman unit, all connections checked, battery good - alt is putting out 14.1 V steady, does not fluctuate with load (rad fan, blower, etc.), belt good and correct tension.

Since driven 100 miles and all good.

I noticed however that the battery icon is still very dimly lit. Dim enough that I initially thought it was just a bit of back light leakage from the tach needle, but the better half noticed it immediately and says it's definitely "on".

I'm kind of surprised as I would assume the lamp is controlled by the ECU digitally, possibly even CANBUS to the cluster as opposed to the ancient "GEN" series incandescent lamps which would flicker .. say at too low idle.

I'm kind of leaning toward a shrug and let it be, but any idea why it would still be lit?


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Dec 1, 2020, 6:48 AM

Post #2 of 5 (116 views)
Re: Toyota Yaris battery light after alternator replaced Sign In

I'm curious about whether the brilliance changes when the throttle is raised.

If it remains at a constant, dim state, then I would tend to blame either the cluster itself or a body ground somewhere.

I assume you are measuring the charging voltage at the battery.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



White Trash CVP
User

Dec 1, 2020, 8:20 AM

Post #3 of 5 (106 views)
Re: Toyota Yaris battery light after alternator replaced Sign In

No the light is steady regardless of RPM or load. As I said though, it's so dim that I wasn't even certain that it was actually on. It's her daily, and she noticed that it wasn't fully out after the alternator replacement.

I'n not even sure if it's LED or a bulb.

Yes, measured at battery terminal.

I didn't bother to dissect the original alternator, just assumed brushes and age. I don't think it suddenly died because she made it home 40 Km in the dark with lights, when I measured I didn't "think" it had any output .. about 12 and change at idle, down to 9-1/2 when the rad fan kicked in, BATT light brilliantly lit, but it might have been still doing a bit to get that far - I recall my old V-70 Volvo wouldn't even make the next ramp running on battery alone.

There's four wires going to this unit (plus main terminal) .. may have to do the Google and see what each is.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Dec 1, 2020, 8:28 AM

Post #4 of 5 (104 views)
Re: Toyota Yaris battery light after alternator replaced Sign In

If not the cluster all FUBARed it's probably seeing low voltage there?
As HT said, body grounds plus more to dash in general.


Testing voltage is info does matter how and where you checked battery. At posts and again outside of posts at the excuse for a U-bolt in post type batteries.


Clues might be weak power to the rest of car high use items include blower to heat/A/C if equipped, rear window defrosters all on then add headlights at idle it shouldn't show 14.1V normally. If it does your reading is wrong.


Power ports should be battery volts about exactly test one FYI the center down inside is pos the outer metal is ground on those. Yup - touch probes to side you'll blow that fuse.


The ultimate test is when engine is cranking to start not always much time so voltmeter or DVOM must be fast watch it drop. Not below 9V for that time if so back to connections, cable quality and those cheap junk U-bolts if not kept greased they fail,


T



Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Dec 1, 2020, 8:50 AM

Post #5 of 5 (101 views)
Re: Toyota Yaris battery light after alternator replaced Sign In

Here is your diagram






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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.







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