Got it. Sounds like the alternator is not keeping the battery charged or you have a drain on the battery, so you are correct that we need to diagnose this system.
This could just be a simple alternator replacement but let's start by getting this tested.
You should be able to have the alternator tested at a parts store as well.
https://www.2carpros.com/articles/how-to-check-a-car-alternator
However, if the vehicle starts and runs fine all day then there is likely a draw on the battery when the vehicle is off.
To test this, we need to check the amperage when the key is off.
You need to hook a meter in series with the negative battery cable so that we can monitor the amperage that is being used when the key is off. Basically, amperage is the measurement of current flow and when the key is off, there should be very little current flow. Just enough to keep things like the clock and module memory alive so this would be less than 35 milliamps (.035 amps).
I am attaching a diagram below that will help set this up.
Here is a guide that will help with common things that cause this draw but once all the doors are closed, the hood latch is flipped so that it thinks the hood is closed the vehicle should go to sleep.
Once this does the amperage should drop but I suspect you have something that is keeping it high, and it drains the battery.
Image (Click to make bigger)
Tuesday, March 29th, 2022 AT 12:06 PM
