Battery/Alternator issue. Voltage is OK

Update:
I checked the voltage again and was at 13.3 idling. I removed the neg cable from the battery terminal and there was all kinds of crud inside the neg cable connector that wasn't visible with it attached to the negative post.
I cleaned it all out and tested again. Now I'm at 14.2 idling.

I drove it about 35 miles, let it sit for 6 hours and it started right up with no issues. Wipers are also working at normal speed.

One question I do have is do you guys experience brightening headlights, fan speeding up etc. when you accelerate or hit the gas when parked or driving? Mine still does that. Voltage regulator??
 
greif07 said:
One question I do have is do you guys experience brightening headlights, fan speeding up etc. when you accelerate or hit the gas when parked or driving? Mine still does that. Voltage regulator??
Click to expand...

Like 19963.4lsr5 said, give the battery a good charge and go from there. Be sure that the battery posts are clean first though as that very well could be your problem. Your lights might dim and get brighter if your battery is still low.
 
So I ordered a kit for the alternator that included new brushes and voltage regulator. Installed today after cleaning the whole thing out with some lecra-motive cleaner. The headlights no longer dim/brighten when on the gas and the same goes for the fan speed. Voltage is great now.

Brushes were pretty worn and voltage regulator had some corrosion, so I should be good to go for another 100k.

:flamethrwoer2:
 
Oh and the new alternator parts came to $26 total. Glad to still have my Denso instead of a parts store special.
 
Just a little FYI, voltage doesn't start the truck, amperage does. A battery could have 12+ volts but not nearly enough CCA to spin the starter. And yes, my blower fan also slows at idle, but only when on high. I have a 6 month old denso alternator. Don't know about the headlights dimming, I have HID's and projectors.
 
TheDurk said:
I cry a little every time I read someone has swapped their Denso as core for an aftermarket or reman.
Click to expand...

Yeah. I thought I had a bad alternator (battery death every 18 months, flickering lights etc) but then I did the Big 3 ugprade and my voltage came up to 14.2 on my ScanGauge.

I've had no problems since.


BTW I've still got the Denso I bought off of EBAY sitting in my Garage ready for install if needed.
 
greif07 said:
So I ordered a kit for the alternator that included new brushes and voltage regulator. Installed today after cleaning the whole thing out with some lecra-motive cleaner. The headlights no longer dim/brighten when on the gas and the same goes for the fan speed. Voltage is great now.

Brushes were pretty worn and voltage regulator had some corrosion, so I should be good to go for another 100k.

:flamethrwoer2:
Click to expand...

Good to hear.

Do you have a part number for such? I opt to replace such before going the remanned way myself.
 
Will someone explain what the Big Three Upgrade is? i'm coming across these threads while searching because my '01 is having power/electrical issues, such as having lights, fans, and wipers that dim/lose some power when rpms are low (not consistently nor severely, but often and noticeably), randomly needing jumpstarts -with weeks of good starts in between- and having things like a fairly new radar detector failing, apparently from voltage issue. The alternator was already replaced last summer, made no difference in these issues, which are not consistent, either. At various points, I've cleaned and tightened cables/ connectors, too, so that's not the cause, and at least the positive cable has been replaced relatively recently. Now its 15-month-old battery has failed completely, and i got a new one on warranty installed today, but i want to figure out what is causing these issues, especially as i might not always be so lucky as i've been about where i'm stranded on the rare occasions it suddenly won't start, sometimes as little as an hour after it's shut off. My prior battery lasted five years without a blip, so it's not how i use it. What's a Big 3 upgrade? and will mechanics know what i'm asking for if i ask for one? i'm not mechanically or electrically inclined myself, but i sure do love my 4runner.
 
It's pretty simple, a good battery reads 12.6V no load engine off, and 13.8V minimum when engine is running. Anything else is a potential problem.
 
The """"big 3 upgrade"" isn't magic. It's upgrading the main battery cables to heavier duty ones. The pos from battery to alt, neg from battery to body sheet metal, neg from body to engine, and neg body to frame.
So actually its a big 4 upgrade if you do it right. There's less loss thru the heavier cables, so the full voltage level will get where it needs to be.
 
While the OP figured out his issues, I would like to add that you need to realize that issues like rectifiers and AC ripple can also be an issue with an alternator and may appear to be charging good enough, could be the cause. Alternators create AC Current and then rectify it into DC current for the rest of the 12v DC system.

Its not always as cut and dry, sometimes further testing is needed.

fourwd1 said:
The """"big 3 upgrade"" isn't magic. It's upgrading the main battery cables to heavier duty ones. The pos from battery to alt, neg from battery to body sheet metal, neg from body to engine, and neg body to frame.
So actually its a big 4 upgrade if you do it right. There's less loss thru the heavier cables, so the full voltage level will get where it needs to be.
Click to expand...

This is very true, its not really a "fix" or a "magic bullet per say. The reason it is typically so effective is because you're basically over-engineering the vehicle. When they designed the vehicle they balanced the cost of cabling vs. the requirements of the vehicle's electrical system; where they decided a more moderate cable thickness was a desirable compromise versus a very thick, efficient (in terms of voltage drop) cable. Not to mention many times people do the "big 3" they are replacing older cables and connectors that have corroded, aged, and increased in resistance over the years (thus creating a larger voltage drop.)
 
Last edited:
First, sorry for reviving this thread. Second, I think its more useful than making a new one.

I've read your post on your alternator issues about you
getting over voltage from your alternator. I'm facing identical issues myself and would like your help.

My battery light has been turning on and off once in a while. When it turns on, I get brighter lights, faster fan, brighter dash lights, the works. It only stays on for a couple seconds, somewhere like 10-15 seconds. And FYI I have also have the big three upgrade already. Also, I just replaced my battery for free under warranty so my battery is fresh.

In addition, I also took it to Autozone to get the electrical tested; battery, starter, charge cycle(diodes). All checked out perfect.

If my voltage regulator is going bad I would like to rebuild my alternator myself. So I wanted to know where you (greif07) bought your parts and if you remember any videos/pictures/forum posts that helped you out to rebuild it. I think LittleCaeser also asked for part #s and such.

Also, about how much time did it take you to rebuild it? Aside from the time to remove it.

Thank you in advance.
 
James_BOND said:
First, sorry for reviving this thread. Second, I think its more useful than making a new one.

I've read your post on your alternator issues about you
getting over voltage from your alternator. I'm facing identical issues myself and would like your help.

My battery light has been turning on and off once in a while. When it turns on, I get brighter lights, faster fan, brighter dash lights, the works. It only stays on for a couple seconds, somewhere like 10-15 seconds. And FYI I have also have the big three upgrade already. Also, I just replaced my battery for free under warranty so my battery is fresh.

In addition, I also took it to Autozone to get the electrical tested; battery, starter, charge cycle(diodes). All checked out perfect.

If my voltage regulator is going bad I would like to rebuild my alternator myself. So I wanted to know where you (greif07) bought your parts and if you remember any videos/pictures/forum posts that helped you out to rebuild it. I think LittleCaeser also asked for part #s and such.

Also, about how much time did it take you to rebuild it? Aside from the time to remove it.

Thank you in advance.
Click to expand...

OK, so now I'm confused. You say it all checked out perfect, but it doesn't actually work correctly? WTF?

Here is a video on rebuilding it, but shouldn't you KNOW it's bad first?

https://www.youtube.com/watch?v=cdqcLdliCQs

I'm not saying rebuilding an alternator is rocket science, but I question whether you have the necessary skills if you can't test it first. No offense intended, I'm asking you more than anything.

:wtf:
 
IBallEngineer said:
OK, so now I'm confused. You say it all checked out perfect, but it doesn't actually work correctly? WTF?

Here is a video on rebuilding it, but shouldn't you KNOW it's bad first?

https://www.youtube.com/watch?v=cdqcLdliCQs

I'm not saying rebuilding an alternator is rocket science, but I question whether you have the necessary skills if you can't test it first. No offense intended, I'm asking you more than anything.

:wtf:
Click to expand...

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!
 
e46inperrycounty said:
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!
Click to expand...

Well yes, but not often. In the "good old days" of mechanical external voltage regulators it happened quite often. Since Chrysler switched in 1973, then GM and Ford followed suit in 75, it doesn't happen all that often. But it can, and does.
:wow:
 
Must be a rare occourance these days. I've seen guys running external VR's and and having issues but I have yet to have one come into the shop with an internal regulated Alt "stuck on WOT" so to speak... They always seem to go out and drop voltage and as they age they tend to get lower and lower. Now I feel bad that the guy at the comp got dq'd for illegal voltage in his lower class and had to run with the guys running 18v+ setups... Nothing like being in a no limit class with vans running 20kwrms or more when you are sitting on 6-7krms and 2 woofers instead of no limit... At that point I'd have just pulled my entry fees and kept my money...lol
 
Time out. First of all I have a computer engineering degree and took at least 10 courses in electronics and all of them had a lab where we build circuits. I've rebuilt an engine myself. An old carburetor on an Isuzu pickup. Have installed a dozen sound systems in all kinds of cars. So YEAH I think I'm good when it comes to figuring out how to build a small physical/mechanical circuit. And another FYI, I took a whole series of physics courses and yes I have had to calculate the mass of the earth, and how to get to the moon so I can almost say, yes I know rocket science.

And to answer your question, when I went to AUTOZONE it was more of a second opinion before I start scratching gunk off my fingers. At the time when I took my 4RUNNER to them, the battery light was not on. 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.

I just posted so I can gather more info, thanks for the video by the way.

Other posibilities that may be going on with my alternator is that it might just be dirty and other people have cleaned it and it worked great just after that. But no one else reported that so I'm thinking about just rebuilding it myself.
 
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