Unknown battery drain

[Charles Land]

I have an 04 Yukon that has developed an unknown battery drain. The battery checks out good. I've changed nothing. This mystery drain started 2 weeks ago. I had an fm transmitter with USB charge ports plugged into the aux power outlet. It's been there for months but thought that maybe it was the drain source and unplugged it. No help.
It's a gradual drain. Takes about a week to drain enough to need a jump.
This is a project vehicle and not my DD. Any suggestions for isolating the power leach would be appreciated. TIA

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Had that problem with my 2011. WalMart tested it and said it was ok. It would discharge in 2-3 days. Replaced the battery and problem went away.
There are some inexpensive clamp on DC ampmmeters on Amazon. That was my next step to see if I could find the load if battery replacement didn't work.

 

[kgkoch]

I purchase a "new" Chrysler car that the previous owner and service shop continued to put batteries and alternators in because of a batter drain. I bought the car cheep and when cleaning it out I heard a him by the back seat. It was coming from the trunk. I listened in the trunk and determined it was the fuel pump in the tank that was running after the engine was turned off. I study the schematics and found that there was a relay under the hood which controlled the fuel pump when the engine was turned off. I took that relay apart and the small spring inside wasn't attached to the electro-magnet switch. I re-attached it. No more battery problems and I had a practically new car for over 50% off its value.
KGKoch

 

[pt1965]

I have an 04 Yukon that has developed an unknown battery drain. The battery checks out good. I've changed nothing. This mystery drain started 2 weeks ago. I had an fm transmitter with USB charge ports plugged into the aux power outlet. It's been there for months but thought that maybe it was the drain source and unplugged it. No help.
It's a gradual drain. Takes about a week to drain enough to need a jump.
This is a project vehicle and not my DD. Any suggestions for isolating the power leach would be appreciated. TIA

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i had an 02 yukon that would eat a battery every 2 yrs. i got a gel to last 3 tho.

 

[mpyrol]

I have an 04 Yukon that has developed an unknown battery drain. The battery checks out good. I've changed nothing. This mystery drain started 2 weeks ago. I had an fm transmitter with USB charge ports plugged into the aux power outlet. It's been there for months but thought that maybe it was the drain source and unplugged it. No help.
It's a gradual drain. Takes about a week to drain enough to need a jump.
This is a project vehicle and not my DD. Any suggestions for isolating the power leach would be appreciated. TIA

Sent from my SM-G930V using Tapatalk

I used this to diagnose a similar issue in my 03 Yukon. https://www.amazon.com/gp/product/B07D2X2JSH

I was able to monitor the battery and was able to notice when there was current flow. The best thing is that you can leave it installed on the dash and look at it periodically. I was able to notice the dash lights do not go out until the door is opened and shut. I think my door pin is sticky. The battery would die overnight. This unit uses a sensor and not a shunt to measure the current. You will notice how long it actually takes for the battery to charge. Mine would pull 20 amps for days after it died. this will give you an idea how well the battery is.

Batteries can kill themselves even though they charge all the way up to 13.8V. The battery can become partially shorted. I just replaced one last week that would charge fine crank all day and die to 6V sitting unhooked. You can check this without buying anything.

You can check for a shorted diode in the alternator if you put it on a oscilloscope and look at the DC. If you see spikes in the waveform, should be a flat line, a shorted diode is indicated.

Hope this helps

 

[04yuke]

Thanks everyone for the awesome suggestions, tips, and advice. Unable to find a source of a drain, I bit the bullet and did a battery replacement. No issues so far. This was a great exercise in me getting to know the 'personality' of the brand and will hopefully serve as a reference for future tahoe/yukon owners with this type of issue. This is a great group and happy that I joined!!

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[Phil Van Beveren]

Like what double said...

Get a test light, disconnect the negative battery cable from the battery. Connect one end of test light to the negative battery cable and the other end to the battery.

If the light comes on then start pulling fuses till the light goes out. The fuse u pull that makes the light go out is the circuit thats giving u trouble.
Note: ECM/BCM circuits always have some draw.

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This works but I don't think a test light is the tool of choice, I'd use an amp-meter. There is always a drain on the battery for things like the security system and radio/stereo presets so the test light will always be light albeit dim. Am Amp-meter will show you the actual drain amount.

 

[exp500]

Any drain over about 100MA will show up after 4-5 days. Some of the 97-99's were always or intermittantly showing 200MA.+. Amazon has a cheap 100 or 200 amp digital ammeter with a coil to go around battery cable.Not for starter cable! Minimum amps is about 20MA but that low accuracy is not good. Seems accurate around 100 MA on up. Hope this helps.