New battery drained

Galamisman,
From the other post (quoted below) ,,, It seems that the ECUs started sometime between 2000 and 2003. I have an '03 and it most certainly has the ECU like the drawing shows and I've put my hands (well finger tips) on it as it's under the dash.

IRT the normal draw for a stock system, I couldn't find any references to that in the FSM. I gather that 200mA is 4x or more what is should be.

Rgs,
dpw

 

50mA is about average parasitic draw, plus the evap pump runs occasionally 24/7. I may not drive my gen2 for several days or more, so I keep a battery tender on it all the time. Better for the battery, and always topped out, ready to go. I do this for my mower, generator, car, truck, everything with an automotive type battery.

 

You likely wouldn't see much of a change in the voltage at least immediately. What you want to measure is the amperage.

Voltage is just how much energy you have left. Amperage is the measure of the energy flow through the system.

Ideally, without the key in the ignition, you should see near zero amps. You'll have a few mili-amps for running the clock and ECU, but that's about it. So maybe 25-50mA.

This has kinda been discussed a bit, but disconnect the neg terminal on the battery, and hook up your multi-meter between the battery and the neg wire you just disconnected. Use the higher amp terminal on your voltmeter (usually 10A)

You will likely see some non-zero amp reading. Now start unplugging fuses one at a time until you see that amperage drop significantly - That's the circuit your parasitic draw is on.

https://www.wikihow.com/Find-a-Parasitic-Battery-Drain

 

A delayed update on my parasitic drain situation. I ended up taking my truck to a local retired "master" Toyota technician. He only takes on little projects which he thinks are fun for a bit of cash.

So, it turns out my totally stock '03 was not actually "stock" after all. I had an aftermarket alarm system which I assumed to be part of the original factory system (I couldn't tell any difference as it used the same stock key fob and I never questioned it). Even though I had narrowed down the circuit to the "Dome" circuit, he felt the best corse of action was to get it back to stock (as it practically was). So after the basic electrical checks passed, most of which I had already done, he commenced to remove the aftermarket alarm. (interesting side note, he said that dealerships often subcontract out things like aftermarket subsystems (i.e., alarms) even though the work is carried out at the dealership by different technicians. That sounds pretty crazy to me, but I'm not too familiar with that world)

Here's the photo of the "tumor" he pulled out from under my dash in a matter of minutes... Doesn't look like much, but when you think about how tight the space is under the dash it adds up quickly. It was cool to watch him identify cables that should not be there in a matter of seconds--pretty impressive. I would never think about cutting out wires from under the dash in modern vehicles.

It has helped a bunch in how long I can keep it parked without jumping it, but I think there is more to go... I need to recheck the present parasitic draw, but it's 80% better.

 

kind of a "standard" practice at dealerships when the factory didnt have an alarm. In my day it was Clifford, the kind with the number keypad. It was the job of F & I guy to up sell the alarm at an obscene markup and if you insisted that it be removed, they removed the fuse that activated it and kept the FOB.

 

@Glamisman, Yeah, I got the feeling he didn't like the fact that the dealership was doing it. He didn't speak too highly of the quality of work that would come out of the subcontractors--apparently my alarm wiring was a clear case of this. I'm sure this isn't the case at all dealerships but he wasn't a big fan of that and he worked 30+ years at one. (by the way, he couldn't speak highly enough of the 1st Gen Tacoma in general)

 

https://www.youtube.com/watch?v=KF1gijj03_0&t=587s

 

I think a parasitic drain is the cause of my dead battery, but when I run the check, I only show between a .01 and a .02 drain with the meter set to the 10A setting. When I switch over to the MA settings, I still show a .02 to a .01 drain. Am I reading the meter incorrectly?

Because of COVID, I only drive the truck once a week at most—but it is surprising that it has been dead multiple times the last month. The battery is only 1yr old and was showing 95% health when I had AutoZone check it last week.

 

@ryangriffith, you have it on the DC setting right? From what I've heard everywhere on TW and other forums is that anything under 50mA (or .05A) should be acceptable.

 

50mA parasitic draw is about right. Plus the evap pump runs once in a while even while off. A new battery can have a dead cell. Load test it. Check all related wiring, clean up every connection. Charging voltage should be 13.8 - 14.2vdc. If you're not driving it much, keep a trickle charger on it. Better for overall battery health, and always topped out.

 

Thanks @06Tacooo and @dpw. I had the battery load-tested and it came back at 95% health. The trickle charger is probably the way to go.

 

I had something similar happen, just a different vehicle. I actually had a sign in my car that said "i need a jump start" for a while. I could not run lights, ac, and radio at the same time if i was in stop and go traffic. The car would regularly die after 2 or three days of no driving. It turned out to be 2 things.
1 was the alternator. How many volt are you getting with the car running? It should be high 13s to low 14s. Apparently the 3 stator windings can fail independently of each other, so it can pass autozones test but the battery is still operating at a loss when you are driving. I pulled my alternator twice and had it tested at 2 different shops. It passed both times. I think also having to really crank on the mounting bolts worked like the old hammer/alternator trick and created a temporary fix.
2 was the line side of the positive cable. About a year of reduced problems and longer battery life the issue came back. I pulled the positive cable from the battery to the alternator and about a foot down there was an extra flexible spot. I cut it open and there was a bunch of hidden corrosion, only about 3 strands of the braided cable were in tact. After replacing the

 

So, it looks like I finally got to the source of my parasitic draw!
The original stock radio is pulling about 200mA. It functions fine but guess something is up with it.

Now need to figure out if I should wire up a cut-out switch like @tacoma_ca recommend in another thread www.tacomaworld.com/threads/parasitic-battery-drain.539364/page-2 or get a new radio.

 

Check your starter sometimes they draw all the time and still start the vehicle. New wet cell batteries, the cells are real close to one another and have lots of problems because of this. The optima battery cells are far apart that’s why they are so good.