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What's draining my battery?

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https://sigforum.com/eve/forums/a/tpc/f/320601935/m/5710011715

September 10, 2025, 09:53 PM
calugo
What's draining my battery?
Thanks for all the advice and I was hoping it would be an easy fix I could take care of myself but looks like it's going to my mechanic for diagnosis and repair.
September 10, 2025, 10:33 PM
Mustang-PaPa
My wifes first mustang a 2006 had a draining the battery issue. It was a known issue with a diode or something in the radio that would go bad and drain the battery in just a few days.
If I recall the issue right as long as you turned the radio off it was fine. This was just a factory am/fm/cd unit.
Never did replace the radio we traded it for a new 08.
September 10, 2025, 11:43 PM
LastCubScout
I had that problem with my 2003 Acura RSX. It was a faulty relay in the air conditioner that would stick open after the ignition was turned off.
September 11, 2025, 07:46 AM
Krazeehorse
If fuses are accessible easily you might start pulling them one by one and reinserting. You might see a slight arc if one is drawing much. You could also check for a draw with a multi meter between the fuse and its terminals using a jumper.


_____________________

Be careful what you tolerate. You are teaching people how to treat you.
September 11, 2025, 07:55 AM
shovelhead
To elaborate on the blower control module, consult AllDATA, available at many public libraries and find out where the connector for the blower module is, usually inside the cabin in the heater box. Pull that connector and see if that makes any difference as there may be a couple circuits feeding power to the HVAC unit.

Next, pull the radio fuse BUT make sure you know how to reset the security code (if it has one) or you’ll be calling or visiting the dealer to reset it.

Next would be to pull the power lead to the alternator and see if that makes any difference. At least if one of these actions stop the draw you can go deeper into it then.


-------------------------------------——————
————————--Ignorance is a powerful tool if applied at the right time, even, usually, surpassing knowledge(E.J.Potter, A.K.A. The Michigan Madman)
September 11, 2025, 05:49 PM
calugo
quote:
Originally posted by 1lowlife:
quote:
Originally posted by calugo:
Bone stock no aftermarket accessories whatsoever and verified all the lights are off inside/outside the truck.


I was going to email you this info, but you don't have an email in your profile.

You can find your wiring diagrams on Tundras.com
Complete with a power source diagram for all circuits.
That way you can see what runs off the BAT, IGN, etc.
It also has all your ground points.
It might help in tracking down your draw.
Although you'll need to create an account and log in to view it.

If you'd like me to send power source diagrams to you, please send me an email, and I'll be happy to do so.

My email is in my profile.


Thanks for the offer but tracking down this fault is beyond my skill level. I had hoped it was something simple until I read all the replies of what could be causing the battery to drain. Monday I'll let my mechanic worry about tracking it down.
September 12, 2025, 09:00 AM
1lowlife
quote:
Originally posted by calugo:

Thanks for the offer but tracking down this fault is beyond my skill level. I had hoped it was something simple until I read all the replies of what could be causing the battery to drain. Monday I'll let my mechanic worry about tracking it down.


Understood.
Please let us know what you find out.
Inquiring minds must know.. Wink

If you have time, check out the forum link in my previous post.
A lot of great Tundra info and some good people there as well.