battery light on
- Thread starter Spish
- Start date
Toyotayoda
New member
Ive run into this issue as well. ABS and Battery light would come on and off but everything was working fine so I thought nothing of it. Then my lows stopped working followed by the high beams. So I went to autozone to check my alternator and the battery was too low on juice to test the alt so through warranty I got a new battery. Alternator checked out at 13.8 according to the guy and my headlights still don't work.Ive checked all the fuses and nothing is burnt.
What else could I check?
Thanks
WOW the cashier at AZ gotcha good, and I said cashier on purpose because they shouldn't be allowed to give auto diagnostic or repair advise to anyone...EVER. you should check your head light bulbs, don't look burned? I bet a couple bulbs are cheaper than an alternator, and easier to replace.
Toyotayoda
New member
I would say you have a bad battery and thats why your charging volts, while within spec, are on the high side. t's just a diode in the alternators internal regulator that decides if the light should be on, I have seen on many occasion where that section of the regulator goes bad, and nothing else, alternator still charges fine. And cars can function like this for years, my personal I would let it be on the the alternator still works ok, use a bs alt indicator that plugs into the cig lighter, and spend money on updates and mods.
Update
Problem solved! Terminal 3 on the alternator plug (which is the sense wire) had no power. I checked and had no continuity between there and Plug EA1, terminal 4 (EA1 is the plug connecting alternator and starter to the Engine Fuse Box). After looking into it, I found a break in the wire (white) right where it branches from the main engine harness to alternator. There was a piece of electrical tape semi-covering it. Not sure if this was factory or a previous owners fix. The tape and the wire was broken due to rubbing on the wire loom protecting the main harness. Opened up the main harness, made the repair and retaped and wireloomed everything.
Without the sense wire, the alternator sees a dead battery (or no battery) and ramps up the voltage to compensate. By the time i figured this out, she was charging @ 15.4V. Apparently, this is why alternators and battery's fail prematurely. The only electrical issues I've developed in this time is I've lost the piezo "chirper" for my alarm and my OBD2 port wont connect with the ECU. Still runs, drives, and charges great. I'll have to look into the other 2 issues. May or may not have been related to overcharging.
Problem solved! Terminal 3 on the alternator plug (which is the sense wire) had no power. I checked and had no continuity between there and Plug EA1, terminal 4 (EA1 is the plug connecting alternator and starter to the Engine Fuse Box). After looking into it, I found a break in the wire (white) right where it branches from the main engine harness to alternator. There was a piece of electrical tape semi-covering it. Not sure if this was factory or a previous owners fix. The tape and the wire was broken due to rubbing on the wire loom protecting the main harness. Opened up the main harness, made the repair and retaped and wireloomed everything.
Without the sense wire, the alternator sees a dead battery (or no battery) and ramps up the voltage to compensate. By the time i figured this out, she was charging @ 15.4V. Apparently, this is why alternators and battery's fail prematurely. The only electrical issues I've developed in this time is I've lost the piezo "chirper" for my alarm and my OBD2 port wont connect with the ECU. Still runs, drives, and charges great. I'll have to look into the other 2 issues. May or may not have been related to overcharging.
Attachments
19963.4lsr5
New member
For your OBD port not working, look for a blown fuse for the sig lighter. Some manufactures use that as the 12v source for the port. I'll verify where the power source for the port comes from when I go to the garage this afternoon (if I remember anyway)
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TheDurk
Elite Member
OBD has its own 7.5 A OBD fuse in Engine Bay Main fuse box.
19963.4lsr5
New member
Ok was heading out to garage soon, my satty, grand Cherokee use power from the cig lighter.
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19963.4lsr5
New member
The cover of the under hood junction has it marked.
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Superman999
New member
Hi, I found broken white wire where three wires from alternator plug meet large loom from beside battery. I was following advice from other post here with picture of problem area.
I cannot find it but it was super advice.
Fixed Wire Problem Gone!
I had confirmed Alternator was charging prior to this.
96 Forerunner SR5 3.4 l Petrol American Issue!
PS Confirm Break by Continuity Test from Fuse No 3 in Fuse Box behind Battery to White Wire at Alternator Plug!
I cannot find it but it was super advice.
Fixed Wire Problem Gone!
I had confirmed Alternator was charging prior to this.
96 Forerunner SR5 3.4 l Petrol American Issue!
PS Confirm Break by Continuity Test from Fuse No 3 in Fuse Box behind Battery to White Wire at Alternator Plug!
RAD4Runner
Senior Member
Good catch.
Toyota components are almost bullet-proof. problems are caused by poor connection, assembly or maintenance.
That's probably the "S" wire. Sends battery voltage back for regulator to sense it. IF that were broken, regulator would think battery is completely discharged and will keep on sending higher voltage to battery, thereby over-charging it.
I’m having issues now. I’m running the Cadillac alternator by ACDelco. Battery light keeps coming on and of. So I was looking at it the other day. And the stud that positive wire mounts to was lose. Ended up taking the alternator apart to tighten the nut that holds the stud in place. Today I was driving and the battery light came back. Now I’m lost. The alternator is 2 months old remanufactured. The battery is yellow top optima about 3 months. What confused me was when I got home. I was moving the wires around. Thinking maybe it had a bad wire. The battery light went away but the volts stayed at 11.8v. So I’m not sure what that is about. It should of jumped back to 14v
19963.4lsr5
New member
How are you adapting the Toyota plug to the GM plug?
Do you have a bulb or LED in the battery light.
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I’m using a harness adapter to plug into the GM alternator. And the dummy light is a bulb. I just checked the volts at battery and it was reading 14.xx volts. So it was charging. It seems to be doing its own thing. I’m aimong towards the alternator !
19963.4lsr5
New member
When you wiggled the wires and the light went out and it was not charging to me it is a issue with the connections between the two harness and the GM alternator.
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Now it’s steady 14v. Lmfao I’m getting the alternator warrantied and new harness adapter.
