[HO455]

You can troubleshoot the problem with a amp meter. First thing is check the capability of the meter. Some are only good for milliamps which may not work for this application.
The next question is do you have an aftermarket stereo? If so it will most likely have a draw on the battery with the key off. Usually there is a specific wire for the clock and memory functions. You will want to isolate that wire from the power circuit before starting.
Once that is done a simple check is to remove the negative battery cable and then touch it to the post. Do you see any sparks? If so then something is drawing power.
Is the spark loud and bright similar to a spark plug spark? If so then it is a fairly large drain that would need a meter capable of measuring 10 or more amps. Any less and you are likely to blow an internal fuse in the meter.
So moving forward set your meter up to measure DC amps. (If you are unsure how the link to the video should help)
Now with the key off you will need to put the meter in line with the negative battery lead. With the negative lead still disconnected put the black lead to the negative post and the red lead to the negative cable. Turn the key on and check what the meter is reading. If you are reading amperage then start pulling fuses one at a time until the meter drops to zero. You may also have to disconnect other components that are not fused but wired into the panel (like your choke)
If when you turn the key on and have disconnected the wire to the radio and there is no amperage reading try reconnecting the l stereo lead and see what the meter shows. It should be down in the milliamps range. If it is higher the stereo may be the problem.

Good luck and let us know what you find.

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