A few months ago my battery went dead after a few days of car sitting, so I installed a new battery then after 3 weeks of usage that one went dead. So I brought it back & got a new one. My check engine light had come on back then too but my sons scanner showed rear bank cat so he cleared it. My son checked everything and found a draw on the battery so pulled the HFL fuse. All has been good and last week check engine light came on, I ignored it thinking it was cat code again, but car sat in driveway since thursday and dead battery today . My son will check for codes again tommorow but if its only the Cat again what could the problem be if the alternator is fine? I'm guessing electrical short? Don't know what it could be since he pulled the HFL fuse months ago and I doubt the battery has a bad cel.

 

The two common battery drains are the HFL and the A/C compressor clutch.

 

Although my son first removed the fuse, today he disconnected the HFL located behind housing near the interior lights above rear view mirror. Is it possible the HFL was still working somehow even though he pulled the fuse? THANKS

 

- If you want to be sure that problem is gone, you will need to measure current going from the battery when car is off.
Easiest way is to get clamp amp meter, I'm using this one :

- Removing fuse as long term fix is not good idea, as other stuff uses same fuse (don't remember now, but it's like mirrors or seat memory system)
Disconnecting directly at the HFL is good idea, as it will be disconnected for 100%, and other stuff can remain powered (put that fuse back in)

- Seems like problem was not properly diagnosed before, so I'm going to ask if HFL module was working before it was disconnected. If it was working (connects to the phone, answers to steering wheel buttons, etc.) then it couldn't be a problem.

- To find what is actually causing draw, use amp meter on the battery, and pull fuse one by one. If you find fuse that causes current to drop by high amount, find out which number and what it is responsible for. Then we can figure out how to solve that issue.

 

Autocorrect sucks

I have been battling the same problem for a year. Have yet to find the problem. Taken it to a mechanic, no shorts found. Was thinking it could be a bad relay. Tried the pull the fuse method, found some circuits that were drawing some power, but nothing significant. Changed the battery also. I don't drive it much, so it does sit for a week at a time, but that shouldn't drain a battery. Really want to resolve this, giving the car to my daughter soon. Don't want her to have to worry about it. I'm at a loss....

 

have you removed the HFL?

 

Happening today. Seen several threads about this, all seem to point to HFL.... which has not worked since I bought 3 years ago. Only had this issue for the last year or so

 

The question still stands. If you haven't removed it yet, I suggest removing it as it may now be causing a drain despite not doing it before. Rule that out by unplugging it.

 

takes 10 minutes to unplug the HFL

 

My HFL is now unplugged and my son reinstalled the fuse, so far no problems