battery light on

[4runna08]

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

 

[lungfish]

Hello DrCoffee
I am experiencing a similar issue as your broken white wire at the ALT. How did you fix the broken wire.? Mine seems to be broken at the connector.
Lungfish

 

[Drcoffee]

Hello DrCoffee
I am experiencing a similar issue as your broken white wire at the ALT. How did you fix the broken wire.? Mine seems to be broken at the connector.
Lungfish

I pulled the wires out of the loom, found the problem and soldered in a new segment of wire a few inches back from the cut to make sure I had clean copper wire. If yours is broken at the connector, you may want to get a replacement connector either at Toyota or a junk yard.

 

[weekendclimber]

its a bigger better alternator with 100amps of juice at idle not the 60 or so the factory one has CS-144 alternator install - YotaTech Forums

I might start another thread as this is off-topic, but any opinions on these: High Output Alternator Fits Toyota 4Runner Tacoma Tundra 3 4L V6 1999 04 170A | eBay

 

[aawolf]

I pulled the wires out of the loom, found the problem and soldered in a new segment of wire a few inches back from the cut to make sure I had clean copper wire. If yours is broken at the connector, you may want to get a replacement connector either at Toyota or a junk yard.

Hey Dr. Coffee-

Are you talking about the positive alternator wire that connects under the gray plastic cover at the alternator?

I intentionally disconnected this wire from the alternator when I performed the big three upgrade. I wanted to make sure the current from the alternator only had one 120A fused path to the battery. Everything seemed fine at the time, but now I think I'm seeing my alternator not giving a full enough charge to my starter battery. Could this be the problem?

 

[Drcoffee]

Hey Dr. Coffee-

Are you talking about the positive alternator wire that connects under the gray plastic cover at the alternator?

I intentionally disconnected this wire from the alternator when I performed the big three upgrade. I wanted to make sure the current from the alternator only had one 120A fused path to the battery. Everything seemed fine at the time, but now I think I'm seeing my alternator not giving a full enough charge to my starter battery. Could this be the problem?

No. I am talking about the thin wires that plug into the alternator. Not the main power cable.

 

[aawolf]

No. I am talking about the thin wires that plug into the alternator. Not the main power cable.

Gotcha, thanks.

As it turns out I was taking an invalid measurement of my alternator's idle voltage. I just finished installing my auxiliary battery's wiring and the truck had been running for more than 5 minutes. The solenoid had clicked on. The 13.3V charging voltage I saw on the primary battery was while the alternator was charging both batteries, not just the primary. When charging just the primary my voltage reaches 13.9V during idle, which I find acceptable.

 

[Megatron222]

‘98 4runner 4x4 Limited Battery Light on and off randomly

Sorry to revive an old thread!!

Looking for some advice please!

My battery light came on about 2 months ago and stayed on. About 2-3 weeks later, I started having starting/cranking issues. Finally, it would not start. Then I replaced the battery and it cranked right up.

About 1-2 weeks later, the battery light was still on, but the engine was cranking fine. During this time, when I was having all of the battery light issues, I had the ECT button on constantly (not knowing this was to only be used in certain instances). In the 3rd week after replacing the battery, I started having cranking issues again.

Sometimes it would start up right away when I turned the key and other times, I would turn the key and nothing would happen. After turning a few more times, it would finally crank. Then I turned the ECT button off, and the battery light started to flicker on and off while the vehicle was moving until finally one day, the battery light just went off completely. I thought it was because I turned OFF the ECT button. Well, it appears that was not the issue. I am now having cranking/starting issues again.

I recently did a 3” coil spacer lift and did not put a diff drop in right away, so I had some grease flung out of the passenger side CV boot. I noticed that some of that grease got on the connections to the starter, so I cleaned that off really well. Haven’t driven it long enough to see if that helped the cranking issues, but today while driving, the battery light came back on!! I tested the output of the battery, alternator, and the starter without load and under load (multiple times) and everything was within normal volt and amp output each time. I have checked fuses and connections but can’t find anything wrong.

The previous owner did note that he never used the factory alarm (red button style beside the steering wheel. You know...the one that goes off like an SOB every time you disconnect the battery) as it could cause battery drain. But I have never had a problem with drain. Just that damn light on.

Please help!!

 

[IsaiahC]

Sorry to revive an old thread!!

Looking for some advice please!

My battery light came on about 2 months ago and stayed on. About 2-3 weeks later, I started having starting/cranking issues. Finally, it would not start. Then I replaced the battery and it cranked right up.

About 1-2 weeks later, the battery light was still on, but the engine was cranking fine. During this time, when I was having all of the battery light issues, I had the ECT button on constantly (not knowing this was to only be used in certain instances). In the 3rd week after replacing the battery, I started having cranking issues again.

Sometimes it would start up right away when I turned the key and other times, I would turn the key and nothing would happen. After turning a few more times, it would finally crank. Then I turned the ECT button off, and the battery light started to flicker on and off while the vehicle was moving until finally one day, the battery light just went off completely. I thought it was because I turned OFF the ECT button. Well, it appears that was not the issue. I am now having cranking/starting issues again.

I recently did a 3” coil spacer lift and did not put a diff drop in right away, so I had some grease flung out of the passenger side CV boot. I noticed that some of that grease got on the connections to the starter, so I cleaned that off really well. Haven’t driven it long enough to see if that helped the cranking issues, but today while driving, the battery light came back on!! I tested the output of the battery, alternator, and the starter without load and under load (multiple times) and everything was within normal volt and amp output each time. I have checked fuses and connections but can’t find anything wrong.

The previous owner did note that he never used the factory alarm (red button style beside the steering wheel. You know...the one that goes off like an SOB every time you disconnect the battery) as it could cause battery drain. But I have never had a problem with drain. Just that damn light on.

Please help!!

Sounds like an alternator that is slowly going out. The new battery didn't have cranking issues at first because it was full charged when you bought it. If the battery light is consistently on, then you can see what kind of outputs your seeing while running. Autozone can do this for free if you don't have a multimeter. Personally, I'd replace the alternator and see if your problems persist. If there is a problem with your alternator, you're not doing your new battery any favors by driving around with the battery light on.

 

[TheDurk]

Sorry to revive an old thread!!

Looking for some advice please!

My battery light came on about 2 months ago and stayed on. About 2-3 weeks later, I started having starting/cranking issues. Finally, it would not start. Then I replaced the battery and it cranked right up.

About 1-2 weeks later, the battery light was still on, but the engine was cranking fine. During this time, when I was having all of the battery light issues, I had the ECT button on constantly (not knowing this was to only be used in certain instances). In the 3rd week after replacing the battery, I started having cranking issues again.

Sometimes it would start up right away when I turned the key and other times, I would turn the key and nothing would happen. After turning a few more times, it would finally crank. Then I turned the ECT button off, and the battery light started to flicker on and off while the vehicle was moving until finally one day, the battery light just went off completely. I thought it was because I turned OFF the ECT button. Well, it appears that was not the issue. I am now having cranking/starting issues again.

I recently did a 3” coil spacer lift and did not put a diff drop in right away, so I had some grease flung out of the passenger side CV boot. I noticed that some of that grease got on the connections to the starter, so I cleaned that off really well. Haven’t driven it long enough to see if that helped the cranking issues, but today while driving, the battery light came back on!! I tested the output of the battery, alternator, and the starter without load and under load (multiple times) and everything was within normal volt and amp output each time. I have checked fuses and connections but can’t find anything wrong.

The previous owner did note that he never used the factory alarm (red button style beside the steering wheel. You know...the one that goes off like an SOB every time you disconnect the battery) as it could cause battery drain. But I have never had a problem with drain. Just that damn light on.

Please help!!

Yeah, I don't believe you. If your alt light is on with engine running you are not getting 'normal' readings. Full stop. Either you don't know what normal is or you're doing it wrong. Spell out exactly what you did and what readings you got from where. Meanwhile, read my post upthread.

 

[Megatron222]

Sounds like an alternator that is slowly going out. The new battery didn't have cranking issues at first because it was full charged when you bought it. If the battery light is consistently on, then you can see what kind of outputs your seeing while running. Autozone can do this for free if you don't have a multimeter. Personally, I'd replace the alternator and see if your problems persist. If there is a problem with your alternator, you're not doing your new battery any favors by driving around with the battery light on.

Thanks for the reply. The guy I bought it from replaced it just before we bought it. I know him so I know he is trustworthy. I did the checks with a voltmeter on the pos/neg terminal. At rest was right at 12.2v. Cranked it up and went to 14.25v. Put it under load (AC full blast, radio on) and it went down to 14.2. Took to AutoZone just to make sure and theirs read damn near the same. Guess it could just be a bad alternator.

 

[Megatron222]

Yeah, I don't believe you. If your alt light is on with engine running you are not getting 'normal' readings. Full stop. Either you don't know what normal is or you're doing it wrong. Spell out exactly what you did and what readings you got from where. Meanwhile, read my post upthread.

Sucks you don't believe someone who is looking for advice...I did the checks with a voltmeter on the pos/neg terminal. At rest was right at 12.2v. Cranked it up and went to 14.25v. Put it under load (AC full blast, radio on) and it went down to 14.2. Took to AutoZone just to make sure and theirs read damn near the same.

 

[TheDurk]

Sucks you don't believe someone who is looking for advice...I did the checks with a voltmeter on the pos/neg terminal. At rest was right at 12.2v. Cranked it up and went to 14.25v. Put it under load (AC full blast, radio on) and it went down to 14.2. Took to AutoZone just to make sure and theirs read damn near the same.

Physics sucks then. That really should not happen. But ok, I'll play along. Maybe I was wrong. You need to double check all your alternator connections because something is not working as it should. Measure the voltage to ground of all four alternator connections at the alternator with the engine running and see what you get. Also double check your 7.5A ALT-S fuse. If you are truly desperate, I'd replace your negative cable and polish up the ground points because true weirdness tends to derive from ground connections. Finally, have your alt tested at a real autoelectric shop that can test it off the truck, not one of these auto parts store computer hookups that leave the alt in place. I have never trusted those. That, or swap the alt.

The only thing I can think of is that 14.2V reading is spurious and is unable to support full charging current to the battery. The alt light does not lie, the battery is not being charged; it is discharging. So you have a bad alt. or bad connections despite your healthy voltage readings. I'm assuming the battery passed a load test. That should be done even if the battery is almost new. A bad alt can kill a battery real fast.

 

[IBallEngineer]

The only thing I can think of is that 14.2V reading is spurious and is unable to support full charging current to the battery. The alt light does not lie, the battery is not being charged; it is discharging. So you have a bad alt. or bad connections despite your healthy voltage readings. I'm assuming the battery passed a load test. That should be done even if the battery is almost new. A bad alt can kill a battery real fast.

Well back in the good old days, wait, these are the good old days. OK, back when Toyota made trucks in Japan with single side wall beds. I was testing an alternator on a pick up that had the light on, it gave me good voltage readings, even under load. But yet the light remained on. I was a young pup in an electrical shop, but not too proud to ask for help. The really sharp troubleshooter didn't even look at the truck, he said the IC regulator was bad. So we pulled the alternator and changed the internal regulator. No more light. I get that even though the field was being excited, there was no removal of ground for the light, but why? How? What the? Truth is, I just don't know.
That was before I really understood a lot, but on the GM cars they had a diode trio that often gave similar symptoms, although generally charging ability suffered too. :redbrick:

 

[hagnecco]

First, I would recommend you take the alt. to a shop that can bench test it for you. This eliminates any possibility the fault is in the on-board wiring. If you settle for a test with it on the motor, make sure they connect right to the alt. Some of these auto-parts stores don't and then try and sell you a new alt when all you needed was a cable. Don't fall into the trap of buying a cheap reman and turning in your stock Denso for core. Try and fix it yourself or get someone to repair it. The after-market and remans probably won't last as long as a repaired Denso.

I have the same issue of the alternator light on, but everything works fine! What should the alternator be charging at? I had a friend bench test it at a shop... said "It's charging fine." I checked it installed and had 13.5V at the battery.

 

[TheDurk]

I have the same issue of the alternator light on, but everything works fine! What should the alternator be charging at? I had a friend bench test it at a shop... said "It's charging fine." I checked it installed and had 13.5V at the battery.

13.5 is fine. Check your wiring.

 

[IBallEngineer]

13.5 is fine. Check your wiring.

I checked and the wiring is still there! heh
opcorn:

 

[hagnecco]

Alternator light on

So, just bought me a 1997 4Runner SR5 3.4L V6 with 310k! Runs great, but has a few quirks. Currently she starts, runs, and drives fine, but the alternator light is on. Here's what I've found, just looking for a second opinion:

Battery by itself - 13.15V

Battery @ idle (no load) - 14.29V
Battery @ idle (under load - 14.15V
Same volts @ 2000 RPM (+/-0.1V)

Alternator @ idle (no load) - 14.34V
Alternator @ 2000rpm (no load) - 14.2V

HERE'S THE KICKER:
Battery rated @ 640 CCA
Load tested @ 144 CCA

Everything looks good on the surface, but could low amps cause the alternator light to come on? Winter is coming and I'll be getting a blemished battery to save $$$ in the morning. Hope this will solve it.

 

[IBallEngineer]

So, just bought me a 1997 4Runner SR5 3.4L V6 with 310k! Runs great, but has a few quirks. Currently she starts, runs, and drives fine, but the alternator light is on. Here's what I've found, just looking for a second opinion:

Battery by itself - 13.15V

Battery @ idle (no load) - 14.29V
Battery @ idle (under load - 14.15V
Same volts @ 2000 RPM (+/-0.1V)

Alternator @ idle (no load) - 14.34V
Alternator @ 2000rpm (no load) - 14.2V

HERE'S THE KICKER:
Battery rated @ 640 CCA
Load tested @ 144 CCA

Everything looks good on the surface, but could low amps cause the alternator light to come on? Winter is coming and I'll be getting a blemished battery to save $$$ in the morning. Hope this will solve it.

To answer the question, no. The alternator light is not an ammeter. It is strictly voltage driven. Here is how it works.

Ignition voltage from the 10A Ignition fuse(driver's side J/B) goes to the combination meter (alt light), then through a diode. From there it goes back to the alternator, or more specifically the IC regulator in the alternator. The IC reg provides a ground initially, so when you turn the key on the alt light should turn on. When you start the vehicle and the alternator starts charging that ground goes away, to keep it simple. Thus with no ground, the light should go out.

This is difficult to trouble shoot, but not impossible. You would need to check voltage/ground at the 3 wire alternator connector. With the connector disconnected, Terminal 1 should be grounded with the engine off(at the alternator) and there should be voltage at the wire side with the key on engine off. Now here is where it get's tricky, with the engine running ground should go away, but the connector needs to be on for it to charge. I'm sure a shunt of some kind could be built to test, but a good bench test is probably more in order. OR swap in a known good alternator or IC reg.

Clear as mud?
:keyboard:

 

[hagnecco]

Mostly clear to say the least.. Went to replace the battery and Interstate tested it just over 600CCA. I called bull and pulled out my fancy Snap On Load tester... showed be 3000+CCA... so i may have a faulty tester.

Here's another idea someone tossed at me. It was suggested that it may be overcharging. Apparently 14V+ seemed high. So a new question I pose is what voltage is considered overcharging? Where can I find exact specs of when this light comes on?

I'm in school right now, but when I get home, I will check the grounds and volts at the 3-wire.