Battery light on 07 Tacoma, not the alternator, not the battery. Solved!

OK so I am new to this form and I would just like to first say hi I’ve heard a lot about this place and lots of positive things........now the problem that I’m having with my 07 Toyota Tacoma is the battery light came on awhile ago, but it came on in a weird way.......I was spraying off the truck with my hose at my house, and I got around to the driver side front fender, and randomly the headlights came on.......so I went inside to look to see if the key were in the ignition, nope..... and the Compass was lit up and reading.....also the controls for the a/c fan speed were on and you could turn the fan speed up and down............ so I tried to turn on the ignition, then turn it off and open the door....(.the headlights go off automatically when you open the door)- Nope. They stayed on........ but here’s where it gets weird........the compass started flickering....along with the headlights, and finally went off. I was like well...... maybe just some water got into something..... and it seemed back to normal...... started the truck up and the battery light was on!!!!!....... BUT the battery and alternator checked out fine, (did load tests on alternator) but replaced the alternator anyway, and the battery light was still on.......changed the battery......still on..... now. When I pull the alternator plug......(green plug) the light goes out. But it’s not charging (obviously). Ive checked every fuse, grounds to chassis/motor/etc......... Oh. One more thing. When I pull the “batt chg” relay, it doesn’t seem to make a difference in voltage or anything. Still right at 14v. So I’ve been driving around with this battery light on for like 3 weeks now. Even made a 350 mile trip with it on. Kinda scary. Any help will be MUCH APPRECIATED!!!!! Sorry it’s so long.

 

I’m leaning toward the under hood fuse box......... any help is appreciated. Thank you guys!

 

How long has this been going on?

 

Battery light has been on solid for about 3 weeks or so. No problems at all before, and no problems now........just a pesky red battery light on my dash.

 

That is insane. I've had something similar happen to my LEDs after going through a mud puddle but the problem went away after pulling the fuse and letting it dry over night. I can't imagine anything could stay wet for that long

 

Funny thing is, I do have Led headlights I put in about 6 months ago.....but I pulled the fuse for the headlights, and fog lights, and started it up and made no difference

 

If you can check the voltage the alternator is putting out when its idling. My corollas alt had the bat light on because it was charging at almost 15 volts. It caused some odd electrical gremlins. you might of messed up the regulator somehow.

 

Ok Empty lord. I will do that tomorrow for sure. Thanks!. Any other thoughts guys?

 

Sounds like an over voltage issue. The alternator can shit the bed in funny ways. Kind of like that girl from Razzoo's. It does great things until it doesn't!

 

if its charging at the right volts its possible the signal wire broke and that why the battery light on. also just amp output if that too low it will kick the light on

 

I'm betting charging system related. The internal voltage regulator in the alternator has crapped the bed. You can get this fixed easily at an auto electric shop in your area and would be far cheaper to fix the alt than replace.

 

He replaced the alternator.

OP did you replace it with OEM toyota?

 

Dang, I missed that! Sorry!

 

How’s the 07 holding up in general? Do you have corrosion under the hood?

All sorts of funky things can happen but my first impression (with the spontaneous lights, compass coming on then flickering.) was ignition switch related or associated wires. Just a guess.

Do you have a scan tool? Throwing any codes??

 

No problems with corrosion at all. It’s been garage kept and I took the cab and bed off and undercoated the frame- And yes. I did replace the alternator, with a remanufactured one from advance And I have a snap on solus and it didn’t see any codes at all. I would try another alternator, but just the weird flickering of the compass, and headlights randomly coming on is what gets me- I’ll make sure keep everyone updated

 

Any schematics on what wire it is? Maybe I could check continuity on it?

 

Ok. So it’s putting out 30-35 amps at idle, then when I turn on the headlights, and heat, it goes to almost 50 amps- Any ideas? And I’m seeing the same 14.0 volts at the post on the alternator. I’m going crazy here

 

Gremlins thats my guess.

 

Can someone see if they unplug the green harness from the alternator on your taco, if the battery light comes on? Because mine goes off. Just seems like the opposite. It would be MUCH appreciated if someone could help me on that. It’s really easy to get to and it’s not gonna hurt anything