2010 SR5 electrical issue

Have a 2010 SR5 w/128k miles that has been in the family since new. Since it was a 3-4 years old, it has been killing batteries (4, possibly 5), headlight bulbs, & 2 alternators to date. Possibly needing a 3rd now. Also just destroyed a 7 month old Interstate battery again. Shop says it's a short somewhere, which I figured or bad ground possibly. Dealership has looked at it in the past when my mom owned it w/no luck (probably no interest in finding it if truth was known), & a few local shops. Current shop says to start by replacing starter & possibly alternator again. Starter could be costly due to location & having to remove exhaust manifold to do so. Was unaware of that design.
Has anyone ever had, or heard of such an issue? Or know about a good way to go about troubleshooting this issue? Thanks in advance!

 

Have you looked at taking it to a legitimate automotive electrical shop? Not just a general auto shop?

 

I will have to look into that. Live in a pretty rural area of VA & don't know of any electrical specialty shops anywhere close.

 

That's a bummer. I live in Chesapeake, VA and took my 4Runner to a dedicated automotive electrical shop (not for the reasons you described) and talked to their techs. They diagnose and repair the exact issue you described.

 

if it is a short it would not necessary be blowing fuses, Somewhere that could be corrosion on the positive side of the electrical system that would place a constant small drain on the battery and they can be rather interesting to chase down, I have spent a great deal of time doing so and have found several areas that are rather common Not only on Toyota's. with one of the most common is the Door switches and rear wiring for trailers they get a green corrosion build up around them and that gunk conducts to ground.

The three tools I use to trace the problem down are simple but need to understand how to use them in a meaningful way. First one is the wiring diagram to locate all the items where the wires go to areas that are most exposed to the outside elements that have positive power at them at all times until something is activated Second I have a simple DC amp / Volt meter to see how many amps things like the starter draw and to see how far down the battery voltage drops when cranking the starter and btw there is always positive power at the starter and I have see that cause many issues of battery drain since they can get very corroded.

3rd Item I use is the super simple fuse tester probe and I have found many more issues using that than anything else however it is a very time consuming hunt if you do not know the wiring system or have electrical diagram. I simply pull one of the battery terminals off and clamp on end on the battery and the other on the wire lug that I took off and the light bulb will light up as long as there is a draw of power next you go pull the fuses 1 X 1 until the light go out and the one that it go out on is the circuit that I check (note the clock and alarm systems pull the fuses for them first) and if it does not and you have all the fuses pulled check the starter cable and alternator power cable for loose connection plus corrosion.
Before starting this make sure the top of the battery is clean no damp white build up anywhere on it.

 

Have you by chance checked the (charging) voltage at the battery? Batteries, bulbs & alternators may possibly be a voltage regulator allowing too much charging voltage. I'm wondering if the regulator is integral with the alternator (which would likely come with an alternator replacement) or if it's an externally mounted unit that has never been checked?

 

He did mention that the Alternator had been previously replaced and nearly all alternators have had internal Voltage regulators since the 70s and some where in the early 2000 many did away with the built in Regulator and depend on the ECU to do the task.

 

Any aftermarket swag installed just before this issue started? Sounds like you have something running in the backgound. (parasitic draw)

Meter your battery at rest, and on/charging. The shut the vehicle off, with the meter on, and watch the voltage. If you have a amp clamp, you could clamp your starter, (like the shop in your post mentioned) and see if its pulling gobs of amperage. Something is draining your rig, if your chewing through bats/alts.

 

You don’t say where the 4Runner was located. Hot climates tend to kill lead acid batteries even when properly maintained. A 3 year lifetime for an Arizona battery is not uncommon.

As previously mentioned you should test for your parasitic current draw to see if it is unusual. Here is a link describing how to do that.
https://www.4runners.com/threads/parasytic-battery-drain.24518/#post-321913