2007 Acura TSX Hands Free Link draining battery

I would definitely NOT replace the module, that's just me. There are a TON of Acuras from this time period that had the faulty HFL BT modules with the parasitic drain.....MDX, TL, TSX just to name a few, all from this era. The problem was systemic and Honda let it go for years. Trust me, your 2006 WILL have this problem and you can't fix it just by replacing the faulty designed part. It was faulty by design. I think you're asking for trouble by just replacing it with the same defectively designed part. Just unplug it, it's not like it will ever do you any good anyhow. Absolutely useless part, I think there was a list of compatible phones at the time, now it's 15 years later, don't bother. Just my .02. I would rather remove(or unplug) the offending part than replace it and end up stranded somewhere with a dead battery just because you stubbornly believe Honda didn't knowingly produce a TON of cars/SUVs with this known defect.

And yes, it should have been recalled, but it WASN'T, so deal with it accordingly.

Of course no one is going to spend US$1400 on an OEM replacement bluetooth module even if Acura gave a lifetime warranty.
I think that Acura gives a 90 warranty on new parts and perhaps zero warranty on electrical/electronic parts...
I also see that there are no updated part numbers on this module, which indicates that Acura/Honda never updated the BT module... lame...


But... $10 on a used BT module from an autowrecker for someone who has strong automotive skills is worthwhile IMO...
The odds are it won't resolve the issue but it's only $10 and a bit of time...


Further thinking on this, if the BT module is draining the battery but it works when the car is running, I wonder if one could wire in a relay to kill the BT module power when the TSX is turned off???
The relay would still power up the BT module when the engine is running...

A temporary switch in the BT module power wire would quickly test this theory...

Thanks Lightspeed... I too have a electronics hardware background but only fix broken software for the last many years...

I have no idea if disabling power to the bluetooth module would even work but it's worth investigating.
A temporary switch to temporarily test the theory but a switch wouldn't be a good permanent solution.
If you jumped out of the car and forgot to turn the switch off, you could kill your battery.

A solid state relay would work but I prefer a mechanical relay for a much lower failure rate.

I just ran out to our garage to check on our TSX's battery. 12.2V, it's fine!
We don't drive our TSX in the winter, I will fire it up today.
We have a beater Honda HRV for winter use.

Disabling power (unplugging module) works as I have found out through my own experience. Also, many others have removed the fuse that powers that module and a zero current drain results. The one caveat that I can think of is that if other devices also draw excess current then you're just slowing down the drain which may work if you drive the car enough...until you don't.

A solid state relay (i.e. Bosch 12V) should work as long it's a Normally Open one and triggered by a circuit that is only powered when the ignition is on. That way the relay closes and allows power (+12V line) to the HFL module when you're driving. They're pretty reliable relays. And yes if you leave the ignition ON (keys in) then you will eventually drain the battery enough...or someone might drive off with it before then. 🤣

And you can also use discrete circuits that use transistors but there really isn't a need here since you're not trying to filter anything, clamp power, clean the signal or regulate it out of necessity. You're just trying to interrupt the power. Of course if you want to play with a mechanical switch while the ignition is On then you can fry the module by creating power surges or spikes.

I understand how having a HFL module is more necessary for some and why it causes so much grief. Luckily It's something I can live without, though it was nice having a hands free phone connection. I can now ignore the phone while driving and enjoy the drive that much more. 😄