I have been running at least 100 miles over the past three months on terribly corrugated and sloppy dirt roads at higher speeds. I'm a duck hunter and that's where the birds are. I probably have shaken one of the connections loose. I'll check those. There is no visible corrosion. Could there be corrosion that I can't see? I have an Interstate battery, should I look at sealed batteries, like an Optima, because of the rough driving I do?

On another note, my OME shocks and springs handle the rough driving very well. That and my KO2's.

Yup.

I checked all of the connections. Plenty of hidden corrosion on the battery connections. After scrubbing them with my Dremel wire brush, I'm now getting 13.9v at the battery terminals at idle. Glad that seems to be the issue. Also glad NTB couldn't get an alternator. Otherwise I would have wasted a couple hundred bucks.

Thanks to all who helped a colleague. Class acts.

I'll definitely second that. My wife has labeled the folks on this forum as my "4Runner friends" because, once again, I have gotten good advice and saved some coin (which she will now be able to spend on her "needs").

Now, since you've cleaned off the terminals, here's a little old school trick.

Get baking soda and put it over the terminals with just a little bit of water. It will most likely foam up a bit. Wait a few minutes, then wash it off with the hose, making sure you wash it all the way down and off the vehicle.

Personally, I spend a lot of money on replacing batteries in all of my vehicles as soon as I get them for a good, quality AGM battery is well-worth the money spent on them, as you have already noticed the amount of time and aggravation spent in dealing with this issue.

Odyssey is my preference, but there are other brands. Sears AGM that's loved here in this forum is a re-badged Odyssey. Yeah, they're upwards of $250 bucks, but you will never get that corrosive acid buildup again. My truck is living proof of that, as its had an Optima since the mid-90's and in the past year, a new Odyssey battery. Terminals were corroded from the previous non-AGM battery in the early 90's, and since that has been removed, I have not had to clean the terminals from corrosion!

Glad it was an easy fix for ya, hopefully that's all it was and your 4r continues to run without issue!

Here's an older school trick: Just pour a bit of Coca Cola out of a can on the terminals. Cleans all the corrosion away quickly just like your method.

Are you taking that reading at the battery or the B+ terminal on the alternator?

Voltage won't mean too much without amperage to compare with. We've seen a handful of alternators in the last couple years putting out "acceptable" voltage but barely any amperage (never did figure out why).

13.9v sounds acceptable and for the most part I wouldn't question it, but something to keep in mind if issue crops up again.

Also I recommend replacing the positive terminal end if the copper is showing, once it's eaten through the grey coating it just seems to corrode that much faster and a new terminal is like $20-ish at the dealer. I see a LOT of severely corroded terminals on fairly new Toyotas, the thin sheet-metal design coupled with batteries off-gassing from a lot of short-trips and such tend to eat those suckers up fast. Couple that with owner negligence in cleaning them off and the owner's wonder why they need a new harness because the terminal end is completely eaten off.

Post Note-

How did you test the battery to verify that it is in good condition?

Another trick I learned from my grandfather many many moons ago....
Either petroleum jelly with baking soda mixed in or axle grease covering all parts of the terminals will prevent corrosion once it has all been cleaned off!

yes, it works...

Terminal on the alternator as the positive, and the negative terminal on the battery as, well, you know. Is this the best way to check it?

The owner of an electrical rebuild shop I've been using for many years once told me to put the red lead from VOM on B+ alternator post and black lead from VOM on the the alternator case(ground). That measures alternator voltage.

In my experience I find that if I see xx.yy at the battery, I see pretty much the same at the alternator, but I check alternator voltage anyway.

How do I check the amperage? I have the 130amp alternator; what kind of numbers should I be seeing from a 120k mile alternator?



I had my local mechanic check it with his computer when my electrical issues began. At that time I had to jump start the truck, so I thought the battery was bad. He checked it ten minutes after jump start and said the battery was healthy and full.

Then, this past weekend, I had both Advance Auto and NTB test it with their machines. Both concurred that the battery was healthy, just not totally charged. They both said that it was because my alternator wasn't charging and the truck's electrical system was running from the battery only. I thought this had to be BS because I had been driving for over two hours with every electrical appliance running except for the inverter and no battery could handle that kind of draw and not show it.

IMO if I ever need another alternator I have the original rebuilt at a starter alternator repair shop. If it can't be rebuilt I would buy OEM. I have had too many failures over the years with Chinese alternators/starters. I Have used baking soda, coke, chassis greese and vasoline. Only thing I find is dirt gets stuck on greese if not covered.

I knew a guy once who did this (not a 4 runner), but failed to wash it off afterwards. Boy was that a messy, sticky disaster all over his battery, the side of the battery, the tray, the frame and a few other spots down the suspension!



Anyways, yes, that works too! Although, wasting a coke is horrendous!