Battery/Alternator issue. Voltage is OK

[IBallEngineer]

I have a computer engineering degree I know rocket science.

I have been saying that my battery light is intermittent. So its on a couple of seconds when I'm driving but it doesn't happen too often. When the light IS on, that's when I get brighter lights, radio goes on protect mode, the works.

Lots of intelligent people on this forum. Sometimes they don't do a good job communicating. Well to be honest we ALL have communicating issues.

So there is a pretty good chance you have an alternator issue, assuming you DO have a good ground on your alternator, battery, block, chassis, and body. And no corrosion on any terminals, etc. etc..

Sounds like you can handle it to me, there is just LOADS of info available on the web, on Alternators in general, and Denso specific. As for parts availability I'm clueless, but you can do that research independent of this forum quicker I think. Then YOU can compile it and post it here and we'd all be forever in your debt!

op2:

 

[Oneluv13T4R]

[MENTION=102597]IBallEngineer[/MENTION] ...

Have you seen a voltage regulator going bad try to overcharge the system? There was a guy from up north who had corrosion inside his Alt and it was trying to charge at 15.5v even though the regulator was a 14.7 regulator. I have only ever heard of it that one time and I was skeptical about the issue because he was a competitor in a fused class. With his voltage being a full volt higher than everyone else in the class his 300 amps of fusing would net him a decent bit more power as the amps tend to really put out some outragious numbers with high voltage and low ohm loads. Never figured out if he was cheating and got caught or if it was a sincere alternator fault but with what this is saying, I'm starting to wonder!

This is what's happening as we speak with my 96 4banger 4Runner ...when I check my battery cold (voltage meter) I'm at 15.05 when I check after start up and engine idling it goes to 15.50 - 15.56 and stays there regardless of headlights, stereo etc. turn off the engine and still stays at 15 - 15.5

This all start this morning when leaving for work ..when I first started it this morning it sounded weak slight hesitation but fired up. Drive 20 mins parked it.
Couple hours later I go to start it .,. Hesitation then just click click click like a dead battery. The street had a slight slope to it so I released the emergency brake rolled 5 ft popped the clutch fired right ...now repeat this scenario a couple more times til now arriving home to figure it ...with the above findings at hand.

Soooo what does it mean ..in layman's terms.
Patter reading for the last couple hours different threads and performing different test ...I'm brain fried.
The conclusion I have come to is my voltage regulator is shot and possibly my battery since exceeding 14.8 volts can cause cell damage and sulfer reaction thingy mcbobber process.

Any help or insight to this weird situation of being at 15.5 volts constant would be awesome ...but you would think with all this power my rig would fire right up? Don't get it at all ...electrical is not my strong suit.

Thanx
Miah

 

[catrains]

if you checked the alternator voltage on a cold start like -40 deg f and it was 15 volts that would be normal. if you did an alternator voltage check when the engine is at normal operating temp and the air temp is 120deg f the voltage would be 13.5volts ...

normal voltage ranges with normal air temps engine at normal operating temp should be between 13.75-14.25volts..

I would first clean all battery connections using a brush secure all grounds clean if necessary. then recheck volts.

over 15 volts with air temp of 30deg f and higher on a cold start is voltage regulator is defective not regulating properly but bad connection can mess up the sensing so wrong charging volts.

yes this reading you measured will cook the battery plates . if alternator is bad have the battery load tested .. a bad battery can kill a new alternator.

buy new alternator not a used one ... used is recycled junk .

 

[IBallEngineer]

[MENTION=102597]IBallEngineer[/MENTION] ...

This is what's happening as we speak with my 96 4banger 4Runner ...when I check my battery cold (voltage meter) I'm at 15.05 when I check after start up and engine idling it goes to 15.50 - 15.56 and stays there regardless of headlights, stereo etc. turn off the engine and still stays at 15 - 15.5

This all start this morning when leaving for work ..when I first started it this morning it sounded weak slight hesitation but fired up. Drive 20 mins parked it.
Couple hours later I go to start it .,. Hesitation then just click click click like a dead battery. The street had a slight slope to it so I released the emergency brake rolled 5 ft popped the clutch fired right ...now repeat this scenario a couple more times til now arriving home to figure it ...with the above findings at hand.

Soooo what does it mean ..in layman's terms.
Patter reading for the last couple hours different threads and performing different test ...I'm brain fried.
The conclusion I have come to is my voltage regulator is shot and possibly my battery since exceeding 14.8 volts can cause cell damage and sulfer reaction thingy mcbobber process.

Any help or insight to this weird situation of being at 15.5 volts constant would be awesome ...but you would think with all this power my rig would fire right up? Don't get it at all ...electrical is not my strong suit.

Thanx
Miah

Well in layman's terms, you could be fighting multiple bogies! But maybe not.

First let me understand, when you say you checked your battery cold, does that mean before starting the vehicle and after sitting overnight?

Then when you got the "click, click, click", did you check voltage then?

And lastly, you may just have a sulfated battery which will jump to a high voltage when quick charged. I'm reaching a little here because that's not a scientific test.

My thought is I would have the battery checked, possibly sub a known good battery to see if you still get the high voltage. If you do, I'd start looking at grounds, or lack thereof, especially to know the alternator has a good ground.

All other things being OK, I'd suspect the battery first, but if a known good battery does the same thing and the grounds are good, I'd blame the alternator. Remember, you should also check that the voltage at the big terminal on the alternator is the same as Battery voltage, within .2 V.

 

[Oneluv13T4R]

if you checked the alternator voltage on a cold start like -40 deg f and it was 15 volts that would be normal. if you did an alternator voltage check when the engine is at normal operating temp and the air temp is 120deg f the voltage would be 13.5volts ...

normal voltage ranges with normal air temps engine at normal operating temp should be between 13.75-14.25volts..

I would first clean all battery connections using a brush secure all grounds clean if necessary. then recheck volts.

over 15 volts with air temp of 30deg f and higher on a cold start is voltage regulator is defective not regulating properly but bad connection can mess up the sensing so wrong charging volts.

yes this reading you measured will cook the battery plates . if alternator is bad have the battery load tested .. a bad battery can kill a new alternator.

buy new alternator not a used one ... used is recycled junk .

Thank you for the explanation to get a better understanding ...yeah I don't do used ever on parts. The only used parts are the original ones on my rigs that I rebuild. I was already looking at parts for a rebuild kit for my alternator if it ends up being the culprit.

Well in layman's terms, you could be fighting multiple bogies! But maybe not.

First let me understand, when you say you checked your battery cold, does that mean before starting the vehicle and after sitting overnight?

Then when you got the "click, click, click", did you check voltage then?

And lastly, you may just have a sulfated battery which will jump to a high voltage when quick charged. I'm reaching a little here because that's not a scientific test.

My thought is I would have the battery checked, possibly sub a known good battery to see if you still get the high voltage. If you do, I'd start looking at grounds, or lack thereof, especially to know the alternator has a good ground.

All other things being OK, I'd suspect the battery first, but if a known good battery does the same thing and the grounds are good, I'd blame the alternator. Remember, you should also check that the voltage at the big terminal on the alternator is the same as Battery voltage, within .2 V.

I appreciate the response, truly
Electrical becomes overwhelming for me at times ...thank you

I will check first thing in the morning my actual cold voltage....got it

If I get the click click click at any point I will check it then as well...take my voltage meter with me...got it

I've used a charger on my battery once overnight after leaving my interior light on one time ...and I've used a Noco power boost on it recently for a quick jump after not completely shutting the rear hatch over the weekend.

Will have the battery checked tomorrow as well on my way home...got it

I do have sub a new battery I bought recently sitting in my garage for when I figure out how to setup a dual battery system in my 4th gen....Lol like I said electrical mods and issues is my weak link. It's an Interstate Deep Cycle Battery. ...sub got it

Then start the process of elimination ..got it

Thanx brotha,
Much appreciated will get back to you in the afternoon and report my day's findings ...

 

[catrains]

the alternators made over the last 10-15 yrs operate at much higher temps than the ones made decades in the past. the winding's get heat damaged as they are now made. the heat load on these is high so in a high temp area I would not waste my time on a re build .

deep cycle battery I would not use .

when you install a dual battery set up both batteries must be the same to avoid problems . one battery can drain the other weird stuff like that ..

 

[hagnecco]

Battery light

So I'm lost with my (new to me) 1997 4Runner 3.4L.. New Alternator, new starter, fresh battery within 6 months, and still my battery light will not go off (this issue has been present since the time of purchase) There is not flickering or random on and off... just a constant glow staring me right in the face. No charging or drivability issues. Starts and runs everytime, even @ -20F.

Here's where I sit... Numbers were all taken @ +36F ambient if that matters.

KOEO:
Battery @ 12.8V, 10 sec load test passed, under load dropped to 11.3V
Positive @ the battery and negative to:
Alternator (positive terminal) - 12.8V
Drivers fender ground - 12.8V
Passenger fender ground - 12.8V
Firewall - 12.8V

KOER:
Battery @ 15.3V
Negative @ battery and positive to:
Alternator case ground - 15.3V
Drivers fender ground - 15.3V
Passenger fender ground - 15.3V
Firewall - 15.3V

Removed, filed and added dielectric grease to ground points at the drivers side fender, passenger side fender, lower block (under the oil filter), firewall, and drivers side intake manifold for the Diagnostice port.

Recently did timing belt, crank seal, camshaft seals, water pump, thermostat, pulleys, tensioners, and all accessory belts, valve cover gaskets, spark plug grommets, spark plug wires, and spark plugs.

The alternator light was on long before I changed the starter and alternator.. Same results. If anyone can tell me what I'm missing, I'd greatly appreciate it.

 

[TheDurk]

So I'm lost with my (new to me) 1997 4Runner 3.4L.. New Alternator, new starter, fresh battery within 6 months, and still my battery light will not go off (this issue has been present since the time of purchase) There is not flickering or random on and off... just a constant glow staring me right in the face. No charging or drivability issues. Starts and runs everytime, even @ -20F.

Here's where I sit... Numbers were all taken @ +36F ambient if that matters.

KOEO:
Battery @ 12.8V, 10 sec load test passed, under load dropped to 11.3V
Positive @ the battery and negative to:
Alternator (positive terminal) - 12.8V
Drivers fender ground - 12.8V
Passenger fender ground - 12.8V
Firewall - 12.8V

KOER:
Battery @ 15.3V
Negative @ battery and positive to:
Alternator case ground - 15.3V
Drivers fender ground - 15.3V
Passenger fender ground - 15.3V
Firewall - 15.3V

Removed, filed and added dielectric grease to ground points at the drivers side fender, passenger side fender, lower block (under the oil filter), firewall, and drivers side intake manifold for the Diagnostice port.

Recently did timing belt, crank seal, camshaft seals, water pump, thermostat, pulleys, tensioners, and all accessory belts, valve cover gaskets, spark plug grommets, spark plug wires, and spark plugs.

The alternator light was on long before I changed the starter and alternator.. Same results. If anyone can tell me what I'm missing, I'd greatly appreciate it.

Hmmmm....you are the second poster with the same issue (he also changed alt.)

Just for fun, unplug the three-wire plug on the alt and turn the key on--don't start it. Does the light stay on then?

Also, while you have the plug out and key on, verify that you have battery voltage on the white wire and red/blue wire at the plug.

Your charging volts are actually above spec, but I don't see how that could cause the problem:

Spec:

At 25 °C (77 °F): 13.7 - 14.7 V
At 115 °C (239 °F): 13.2 - 14.0 V

Here is the '97 Charging EWD:

 

[IBallEngineer]

Hmmmm....you are the second poster with the same issue (he also changed alt.)

Just for fun, unplug the three-wire plug on the alt and turn the key on--don't start it. Does the light stay on then?

Also, while you have the plug out and key on, verify that you have battery voltage on the white wire and red/blue wire at the plug.

Your charging volts are actually above spec, but I don't see how that could cause the problem:

Spec:

Here is the '97 Charging EWD:

I actually thing they are TOO far above spec for normal operation, but I'm not clear how that affects the light operation. No matter, here is the bottom line.

The light in the dash takes power from the 7.5A ign fuse then the ground side flows through a diode to the IC regulator. Term 2 on the 3 wire alternator plug, or the L terminal on the alternator. When you turn the KOEO the light is grounded at the alternator/regulator, you didn't specify that the light turns on before you start the engine.

Once you start the engine the diodes send voltage back out the L terminal, thereby "taking away" ground for the light and it goes out.

If you follow [MENTION=10169]TheDurk[/MENTION] 's instruction removing the plug and checking the light, and it lights, the problem is not IN your alternator but rather somewhere in the light circuit. If it doesn't light, there are some further tests you can do. Starting with this:

http://tacoma.site40.net/4Runner_96-02_Repair&Wiring/techinfo.toyota.com/ileaf/02toyrm/02toypdf/02rmsour/2002/024runne/ch5vzfe/gene/insp.pdf

You can also have the alternator bench tested, just because you replaced it doesn't mean it's good. But the other issue is whether your vehicle is causing the alternator failure. Search the threads for the Big 3 modification, it exists for a reason. Here is another link explaining voltage drop affecting the diode function in the alternator.

Helpful Tech Tips From Car Repair Professionals

I need to do some garage work to figure out how to test the diode in the comb meter, and/or if it can cause this sort of problem.

:shrug:

 

[TheDurk]

I need to do some garage work to figure out how to test the diode in the comb meter, and/or if it can cause this sort of problem.

:shrug:

Yeah, I was thinking about that. Here is what I came up with.

If it is open, you get no light period. If it is shorted, it should not affect the light going out when the alt. is charging.

The diode is there to prevent the alternator from backfeeding current to the ignition circuit once you have turned the key off, thus causing the engine to keep running.

You don't necessarily need a diode to do that. Just the light may be sufficient, depending on its resistance, or you can use a resistor in place of the diode.

My tractor with an alternator conversion I installed works fine with just a light and no diode. My tractor buddies have a lot of experience in wiring up alternator conversions from the original generators.

If I'm wrong, I'm happy to learn.

I'm really hoping the light stays on with the alt out of the circuit, and then we can just chase a short to ground.

 

[phattyduck]

15.3V with the engine running (even at cold temps) is much too high. I would suspect a bad 'new' alternator.

-Charlie

 

[19963.4lsr5]

I agree with a bad alternator. That bulb is between the power wire in the ignition circuit and the ALT's voltage output. Any difference in voltage between the two ends of the wire will cause the bulb to illuminate in proportion to the difference. I think the regulator sense circuit is going bad and has a partial ground and that illuminates and raises the output to 15+ volts to compensate.


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[hagnecco]

Hmmmm....you are the second poster with the same issue (he also changed alt.)

Just for fun, unplug the three-wire plug on the alt and turn the key on--don't start it. Does the light stay on then?

Also, while you have the plug out and key on, verify that you have battery voltage on the white wire and red/blue wire at the plug.

Your charging volts are actually above spec, but I don't see how that could cause the problem:

Spec:



Here is the '97 Charging EWD:

So it was late and I knew I was missing some details. When I bought this, the battery wasn't charging. Replaced the alternator and still the same issue. I can't recall if the light was on or not.

The 3 wire plug was haggered and had loose contacts. I purchased a new plug off amazon, chopped off the old, and spliced in the new.. so the color wires don't match the original, but I matched up the colors left to right according to the old plug.

The specs I gave last night are when I started the vehicle cold. Today its +25F and after she warmed up with a drive into town, she settled down to 15.0V. Still "seems" high, but I don't see that being an issue.

Now what I did today..

KOEO
Battery light on
pulled the plug... battery light off!!
Wires numbered in order left to right, just like page two of your schematic..
I will have to pull back the wire loom to see what colors they are.
Wire 1: 11.99V
Wire 2: 12.25V
Wire 3: 0.0V

Did I get 2 of the wires crossed? If so, how do I check to see which goes where?

 

[TheDurk]

So it was late and I knew I was missing some details. When I bought this, the battery wasn't charging. Replaced the alternator and still the same issue. I can't recall if the light was on or not.

The 3 wire plug was haggered and had loose contacts. I purchased a new plug off amazon, chopped off the old, and spliced in the new.. so the color wires don't match the original, but I matched up the colors left to right according to the old plug.

The specs I gave last night are when I started the vehicle cold. Today its +25F and after she warmed up with a drive into town, she settled down to 15.0V. Still "seems" high, but I don't see that being an issue.

Now what I did today..

KOEO
Battery light on
pulled the plug... battery light off!!
Wires numbered in order left to right, just like page two of your schematic..
I will have to pull back the wire loom to see what colors they are.
Wire 1: 11.99V
Wire 2: 12.25V
Wire 3: 0.0V

Did I get 2 of the wires crossed? If so, how do I check to see which goes where?

Yeah, I think you did. Wires 1 and 3 should have battery voltage. The one showing zero volts is the light. Prove that by grounding it with key on and the light should come on. I would think the higher voltage should be on Wire 3. So I'd say you have Wires 2 and 3 swapped. But you should really confirm this by looking at the original wires and matching to the EWD. Note that the pin-out of that plug is shown on the last page of the EWD as Plug G1. I think we found our gremlin.

This may well solve your voltage problem. I think you have the "Sense" terminal connected to the light and that might cause the alt. to max out when not needed.

 

[19963.4lsr5]

Please define wires 1-3 as left to right or actual terminal numbers. And OEM wire color.

To me one of those wires should be the sense wire. And I see nothing close to system voltage.


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[hagnecco]

Alternator plug

Please define wires 1-3 as left to right or actual terminal numbers. And OEM wire color.

To me one of those wires should be the sense wire. And I see nothing close to system voltage.


Sent from my iPhone using Tapatalk

Left to right, wire #'s 1,2,3, see the attached photo.

I think I did wire it correctly, because with KOEO:
I have 12.8V @ wire #1. When I pull the 7.5A IGN fuse, I loose power to wire #1.
I have 12.8V @ wire #2. When I pull the 10A Gauge fuse, I nearly loose power.. this drops to 0.1V. (shouldn't this drop to 0.0V?)

That leaves wire #3. which I don't know how to check.
with KOEO, I have battery voltage of 12.8V @ the 7.5A Alt-S fuse.
with KOER, I have alternator voltage of 15.0V @ the 7.5A Alt-S fuse.


I do not have colors, because I will have to peel back the wire loom covering it. The amazon plug I bought does not match wire colors.

 

[19963.4lsr5]

Left to right, wire #'s 1,2,3



I do not have colors, because I will have to peel back the wire loom covering it. The amazon plug I bought does not match wire colors.

Ok. The fun part. Installed and looking from the front of 4Runner? Plug removed and staring at the open connector holes?

What orientation? Draw a picture of the alt with plug installed and the three wires and their readings. Then take a picture of it and post it.


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[outdoorjunky]

I had a similar issue with a brand new aftermarket (US made alternator) that I put in my old 94 22R pickup in a pinch ... Voltage was fine but Amps were not to spec so I had to replace it again with a OEM alternator. Try checking the amperage as well because even if the voltage is clean on the alternator it could be that it's not putting out enough amps.

 

[TheDurk]

Ok. The fun part. Installed and looking from the front of 4Runner? Plug removed and staring at the open connector holes?

What orientation? Draw a picture of the alt with plug installed and the three wires and their readings. Then take a picture of it and post it.


Sent from my iPhone using Tapatalk

That is looking at the face of the plug. The wires leave out the back. The lock is on the top which is kind of obvious. The numbers correspond to the numbers on the wire diagram which also shows the colors. I could write them down for you, but all the info is there and it is better to learn how to do it that be told the answers.

 

[TheDurk]

Left to right, wire #'s 1,2,3, see the attached photo.

I think I did wire it correctly, because with KOEO, I have 12.8V @ wire #1. When I pull the 7.5A IGN fuse, I loose power to wire #1.

Also with KOEO, I have 12.8V @ wire #2. When I pull the 10A Gauge fuse, nearly loose power.. this drops to 0.1V.

That leaves wire #3 which I don't know how to check.


I do not have colors, because I will have to peel back the wire loom covering it. The amazon plug I bought does not match wire colors.

Yeah, that #3 wire needs to show battery voltage. That is the sense wire I was talking about. You need to check both sides of the ALT-S fuse. In fact, better to swap in a known good fuse and then see what you get.