I’ve got a 2013 CX5 with a large battery drain. It draws from ~1.1 to 1.5 amps. If not driven everyday it needs a boost to start.

In the 5 years we’ve owned it always needed to run every couple days to charge the battery, but in the last 6 months it has gotten worse to the current point. Nothing has been added or modified in that time.

Pulling every fuse and relay does not stop the drain. Both the alternator and starter being disconnected also does not remove the drain.

We’ve taken it to a mechanic and they agreed pulling fuses and relays has zero affect, and alternator and starter have no impact on the drain. Their opinion is that the BCM or PCM is not sleeping and stays awake. I’ve tried to replicate this by disconnecting both modules and the drain remains.

Has anyone seen something similar? Next step is probably take it to the dealer and have them throw parts at it but that won’t be wallet friendly.

 

How long did you wait after pulling each fuse?

 

30 sec-1 min. Also removing the main cable from the positive battery terminal that powers the under hood fuse box does nothing.

 

There are multiple electrical TSB's for the 2013 including corroded connectors.
There are known issues with the parking sensor on some vehicles (vehicle may not shut off or may shut off but it still thinks it's running).
Average draw on the CX-5 is 40-65 mA.
I would also note my OEM battery only lasted 1 year before it died.

 

That eliminates everything attached to the B+ cable, which would logically leave only the cable itself as the culprit. Some very simple and easy voltage drop testing of the cable should be able to quickly confirm exactly where the problem is.

 

I had the same nightmare with a mazda6. So I feel your pain. After many visits to different garages. I finally found a guy that found the problem. And it was the bluetooth module inside the dash that was faulty

 

Yup, that'll do it in a lot of cars.