Dead battery every Monday

Need help, Toyota says nothing is wrong with the truck.
As soon as the weather starts to turn cooler, if my truck sits for 2 days I have to boost it. It is my work truck so basically every Monday morning I am having to jumpstart this thing from Oct-March. There are NO mods, battery have been replaced 2x and it’s a 2017. Thoughts?

 

Do you can access to a meter to measure current draw? Toyota is extremely conscious of having almost all power off to the battery when the truck is “off”. Only the ignition circuit draws a few milliamperes when the truck is off.

A good battery does not drain itself that quickly. A bad battery certainly can. It has to be a load on the battery, or the battery itself.

 

Electrical short? I would have the dealership run full diagnostic on the electrical system, load test the battery etc. that’s not normal man, what a pain in the ass

 

If the battery had been load tested and passes, then you have excessive load while parked. Remove the ground. Place an Amp meter in series and see what type of draw you have with the accessories and ignition off. If you have high amp draw, start pulling fuses until you find the culprit. Then once you find the circuit, figure out which device it is. A good Toyota tech should be able to do this. But then again... this is old school diagnostics, not modern laptops and lattes diagnostics.


Do you have any aftermarket wiring installed. Start there.

 

Welcome.
You might want to provide:
More specifics on the model;
Your location (so people can direct you to more reputable dealers/mechanics); and
Take your truck on a daily drive until the problems sorted out.

Good Luck!

 

If you have a DVOM, with the key off you can disconnect the positive battery cable, place the leads in between the positive terminal and battery cable and see what your current draw is. With the key off you should only be drawing a few milliamps, if it's drawing more then that then something is not shutting down, you can start pulling fuses and relays one at a time until the current draw drops. That way you can narrow it down to what circuit is causing the draw.

 

There is something wrong. I ride my motorcycle most of the year, so my truck will sit for several days. It has sat for 3 weeks without being started and when I did go to use it, it started right up with no issues. This is in Louisiana, so not really cold, although we have been in the teens before, but our summers are brutal.

 

For what it may be worth?

Yesterday I heard a strange noise coming from the truck (it had been parked for a few hours). Searching for the noise, I'm pretty sure that it was coming from the E-Vap Canister. I believe that the pump was running? I have a post in the Technical Forum questioning if others have heard this? I was slightly concerned with current draw on the battery.

 

either the battery is defective or you have a parasitic electrical draw, or both. Even though you've had that battery checked, have it done again. Many of the auto parts stores will do this at no cost. If battery is okay, then do the diagnostics mentioned above in this thread. The wiring on these modern vehicles is fairly complex and there's a lot that can go wrong. I had a Ultra Gauge plugged into my OBD II port which turned out to be a parasite in my 2019. I had the same unit plugged into my 2018 with not issue, so it seems Toyota is leaving a bit of power to the device even when the truck is powered off. Not saying that's your issue, just illustrating how things you don't expect can be the problem.

Until you get it sorted out, maybe hook up a battery tender over the weekend.

 

This is explained in the manual. It happens about 5 hours after being parked. Completely normal operation and will not draw enough to kill the battery.

 

This only happens once five hours after you shut the vehicle off. It won't occur on consecutive days that the vehicle has been sitting parked.

 

That is a normal scheduled operation in any modern vehicle. It has to happen a certain number of hours after the vehicle is shut down. The pump will draw current while it is running, but this is expected and the battery can handle it. It only happens once after turning off the vehicle, so it does not happen again if the vehicle is parked for several days.

 

Interesting

 

A bad alternator will cause the battery to discharge more than normal killing the battery. It can kill the replacement as well if not remedied.

 

True, if the battery is not being charged by the alternator. Good point. I guess I was assuming Toyota would have checked the battery was being charged, but who knows? Maybe the dealership has no talented staff.

 

Not old school, it's still taught and was used back when I was a tech. There should be a spec for what is excessive dark current/key off draw.

Old school would be pulling out a test light to measure key off draw.

 

Do you have anything plugged into the cigarette lighter? But i think those are dead when the ignition is off anyways. Check to see if you have anything plugged into your battery posts, and see if there is corrosion on the terminals

 

Now that right there is funny.

 

This is normal on all vehicles now. The purge pump is low draw and only comes on for a short time anywhere for a few minutes to a few hours after shutting of the engine.

 

Once...if it's able to perform the purge.