Problem: Overnight battery drain leaving me with a dead battery in the morning.
Disconnecting the battery cable overnight stopped whatever is killing the battery.
So I concluded there was a draw.

After performing the test for a battery drain, the fuse that stopped the drain was the Audio fuse, which is fuse #1 in the under the dash fuse panel.

Multimeter was hooked up and after allowing enough time for everything to go into Sleep Mode, multimeter showed a 70 milliamp draw. Pulling the Audio fuse brought the draw down 15 milliamp. With that Audio fuse pulled overnight, Navigator had no trouble starting this morning. So that's good, at least.

So my question is: Now what?

Bad radio unit?
Bad CD changer?
Bad amp?
Bad subwoofer? (which hasn't worked in years)?

Where do I start?

 

70 ma should be nowhere near enough of a draw to drain a battery overnight, there's something else going on there. One amp=1,000 ma, making there about 14.28 70 milliamps in one amp (1,000/70). That means that if the vehicle sits about 14 hours and 15 minutes that 800 or so amp battery would lose only one amp. I suspect the amp, radio, or CD changer might be coming on at various times overnight and adding to the battery draw.

 

Yes, I agree this draw is not major. I suspect this drain is not new. It's just in the Winter I go more than a couple of days without driving it. Plus it's cold. I think my 3 year old battery has been weakened by this problem. Normally, the drain would not kill the battery overnight, but older, weaker battery, intermittent use of car for the last several weeks, plus the cold weather is causing this drain to present itself now.

(I should also mention that my oem radio has not worked right for several years. The volume button is erratic, it's seems to be quite warm to the touch after use, etc. And my subwoofer hasn't worked in several years. No idea why.)

I really don't know where else to start so I just went ahead and bought a used oem radio ($40) off ebay. When it arrives I will swap radios and see what happens.

 

Another place to check is the rear wiper, very common for parasitic drain.

 

Try unplugging that amplifier back by the third seat. It's behind the trim panels in the right rear. See if that reduces the parasitic draw.

 

Is the amplifier located near the subwoofer?

 

Yes. Kind of a pain to get to, but my amp was what kept blowing fuse #1. Radio sounds kinda weird with the amp disconnected. Your amp may also be causing your radio to sound weird. Amps are usually floating around on e@bay.

 

I'll check it out. Thanks for the idea.

 

Update: I replaced the oem radio unit with a used oem unit. Re-did the battery drain test. No Fix -- Over 70 milliamps of draw.
(I needed a new radio, anyway. The volume **** wasn't working and did whatever it wanted to most of the time.)

Then I went to the very end of of the Audio system and unplugged the subwoofer. No Fix.

Then I unplugged the Amplifier which is right in front of the subwoofer. FIX. The draw went down to about 10 milliamps.

The Amp seems to be the problem. Will update later, off to the ebays...

 

I removed the amplifier and opened it up. Here's what I found:






I don't know anything about electronics so it'd be great if someone could explain what parts got smoked and how it would cause a continuous draw.

 

Blown MOSFET, probably the final (or one of) amplifying component. Replace the amplifier module, toss that one in the recycle pile.

Good work tracking down the current leak!

 

Yes it could be a MOSFET, but considering it's alone, the lack of heat sink fins, and it's proximity to a PC fuse, some diodes and that capacitor, it could also be the input voltage regulator.

 

Google the part number on the device.... (BUK453)

It could have any of a number of functions.

 

Well I wasn't trying to start a debate, but since you asked, I did find this...

https://octopart.com/buk453-100a-nxp...uctors-2291683

Descriptions: N-channel enhancement mode field-effect power transistor in a plastic envelope. Applications: switched mode power supplies(SMPS)

 

Suggested applications are simply that - suggestions. It's up to the actual design engineer to figure out how it's to be used in the final product. Like I said before it could be performing any of a number of possible functions, we simply don't know. My initial suggestion was made after looking only at the PCB silkscreen (which defined it as an FET of some type) and the additional heat sink (visible in first photo, removed in second). Sometimes, the lack of scope of the supplied photos limits the ideas about the function.

In any event, the OP's fault has been identified and the corrective actions have been identified. 'nuff said.