2015 4Runner Battery Light On

[Proffesor_X]

2015 4Runner Battery Light On - I have been researching this for weeks and still cant find a fix. Someone (I cant say who, wasnt me) connected the battery leads incorrectly and ended up putting the positive on the negative and the negative on the positive. So I ended up replacing the 140amp fuse along with all the other fuses I could find that blew. Battery light was still on. So I went and had my alternator tested at Autozone and it checked out. But I still felt uneasy and managed to borrow an OEM alternator directly off the same model of car. Hooked it up and the battery is still on. I have tried everything I know of and the battery light is still on. When the car is on the alternator charges and battery(I tested with a voltmeter) and I dont know where to go from here. Any help would be appreciated. Thank you.

 

[Jivewalker]

I would go through all the connections at the alternator, may be a loose harness. Also, check the ground connections. What voltage do you get at the battery terminals with engine idling? Why was the battery disconnected to begin with, were you doing some work? That may help narrow it down.

 

[catrains]

why is it that you do not know who connected the battery wrong ?

the problem when a battery is connected reverse then the PCM and other diodes will get damaged and perhaps more fuses.

many idiots have put jumper cables on in reverse and this also creates these type problems.

on all my vehicles I use red paint on the battery plus so this is a very clear indication of where the positive is .

 

[Auntie Soshul]

why is it that you do not know who connected the battery wrong ?

I got the impression that he knows who did it but prefers not to say. Could have been his dad, wife, or maybe another member of this forum.

 

[Proffesor_X]

I got the impression that he knows who did it but prefers not to say. Could have been his dad, wife, or maybe another member of this forum.

Yes. I cannot not say who. Its not that I do not know, I would just not prefer to say.

 

[Proffesor_X]

I would go through all the connections at the alternator, may be a loose harness. Also, check the ground connections. What voltage do you get at the battery terminals with engine idling? Why was the battery disconnected to begin with, were you doing some work? That may help narrow it down.

I went through the connections on the alternator and they seemed to be good. At idle the charge is 13.95 volts. The battery was disconnected to get a better view of the fuse box and clean up some dirt around that area. Another note. I read the voltage drop on the positive side is suppose to be 200 millivolts. However I tested the voltage drop between the positive lead of the battery and the alternator output and the voltage drop was 300 millivolts.

 

[nglayton]

Did you check the 7.5 amp ALT-S fuse?

 

[Proffesor_X]

Did you check the 7.5 amp ALT-S fuse?

Yes. The fuse didnt burn. However I read somewhere on this forum that someone replaced that fuse even when it was intact and the light when away. I did the same, however the light is still there.

 

[Deep_palancar]

Where are you with this? Do you have the wiring diagrams?
I have diagrams and a theory but did not want to transmit if you've got this fixed.