Hello to you. I had the same problem. Needed to change my battery 3 times. I finnally took my car to a Mazda dealer (could not locate the parasit current) to Fix it. It took them a lot time and work and money [$300) to find the cause. They said the radio was defective but there was no way to fix it. They also said some research within Mazda service notes were mentionning this particular (and apparently rare) problem.

so I am seaching for a similar radio for Mazda... to change it by myself.

Denis from Canada

 

DenisThis whole adventure started when the radio started to go bad - turning on and off all by itself. What's interesting is that, with the radio completely disconnected, a drain was still present. When the 'mystery' wire was disconnected and the radio re-connected, the drain was gone, and the radio remained dead. Perhaps a short originating in the radio shorted out something else in the harness that contains the mystery wire. In any case, I appreciate your comment about what your Mazda dealer said about there being no way to fix the radio. We had already bought, but not yet installed, an aftermarket unit from Crutchfield but were thinking of sending the stock radio to Mazda to repair before installing the unit we got from Crutchfield. Given your comment, we'll probably just have the Crutchfield unit installed. After that, I'll have the mystery wire re-connected and seen f the drain returns. If it does, we'll just disconnect the mystery wire for good.

 

I know from the technicien that he needed to wait some time after disconnecting a wire before testing again for a current leak. I am actually seaching for a similar radio to install by myself. It may have to go to Mazda to get activated with a code (i will see at this time). But one thing is for sure, if I improve the same problem with my car (dead battery), I will clame my money back if they didn’t identify the problem correctly. Please let me know what happen on your side...

😉

 

Looking for battery drain requires pulling fuses until the fuse controlling the offending circuit is identified. HOWEVER, each time a fuse is pulled, the car needs to go 'to sleep' COMPLETELY before a drain can be isolated. That's because various controllers stay 'awake' after the power is off - sometimes an hour or so - before they go to sleep and no longer create a drain on the battery. For the car to be completely 'asleep' where no controller or sensor is on and using power, EVERYTHING needs to be asleep. Open doors or even an open hood can keep various sensors 'awake' and creating a power draw.

 

Wow, thank you for the information...

 

Oct 2020 Dead Battery. Nov 2020 replaced battery, then that went dead (Dec 2020). Dec 2020 took it to Mazda they said battery was bad and the BCM was bad. Returned battery to Sam's and got a replacement, paid Mazda to replace BCM (Jan 2021). Worked for about 2-3 weeks and then dead (Feb 2021). (Feb 2021) Brought back to Mazda to look for original battery drain fault. They have had car 40 days.

So I don't really need the car right now, but assuming they cannot fix it... how do I get rid of car with parasitic drain? Who would buy it?

UPDATE: April 2022 (Not 2021). Fixed, no more issues.

Mazda finally came back and said it was the alternator and they changed it. After about 2-3 weeks the battery died again... When Sam's club checked it they said it had a bad cell (same fault as before). I decided the parasitic drain just was and I could not do anything about it and it was killing batteries. I put in a new battery and installed a kill switch for about 6 months with no issues.

I do not use the kill switch now. Here is what I think was wrong... I had a brand new battery when they replaced the BCM, but the bad alternator killed that new battery. When I took it back in to Mazda I assumed the battery was just drained and not destroyed... they replaced the alternator, but the battery was destroyed by then so it appeared the new alternator did not fix it. When I put in a new battery after I changed the alternator everything worked. I have no issues now.

I'm guessing the alternator showed up as good on their machine just like mine because it was charging... but it was the ultimately the alternator that was bad.

So it took roughly about 15 months for me to get from original fault back to normal.

UPDATE: July 2022. Really Fixed , no more issues.

I think the new battery kept it from dying for awhile, but ultimately it died again. I put a battery kill switch on the negative post and set off to look for someone to install a kill switch inside the cab. Took to an audio/alarm guy who wanted to see if he could fix it first before he put in the kill switch. He thought without ever touching or looking at it that it was a Bluetooth Module. He disconnected the BT and there are no more issues. I'm guessing I did not need an alternator. 31 months from fault to fix.

Ignore the terms below as I'm going to build some search terms for others.

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I have the exact same issue as you. 200 mA draw with doors locked and only 50 mA when unlocked. Just wondering if you ever figured it out?

 

Thanks everyone for this great info. I'm having the very same issue and have checked every circuit. .213 A draw , battery dead in 3 days, 2nd new battery. Did anyone ever find the culprit?

Thanks in advance.

 

I'd like to know what, if anything, has been identified as the culprit as well.

Had the same bizarre radio issues and ever since it was replaced with a Kenwood radio from Cruchfield, 3 days and dead.

It was odd though. The Crutchfield guys, who are awesome btw, could not get this new radio on with the harness.

We had to run a wire elsewhere to get it hot. Then, and this is good, it turns on and everything is wonderful... once. Then the radio turns on normally when turning the vehicle's ignition on, but no sound. Replaced the amp, no dice. So to make it work, I have to reset the radio or remove the negative on the battery after each drive, which we do. The good news is that this keeps the battery charged and makes the radio work at the same time. Of course, it's a pain and we shouldn't have to do that.

Has anyone figured this madness out?

 

I just went through all this with my son's 2008 Mazda 3 GT. No crank, no start when the temperature was below -10C (Saskatchewan). The idiots at two different Mazda dealer told me that wasn't a thing after 2006. No recall, no TSB. Long story short, I replaced the ignition relay (not the main), starts fine.
UPDATE: replaced both main and ignition relays as the other one needed to be too. There is also a TSB to splice in a new starter wire connection right at the starter because it corrodes. We had to do this too as he was still having issues in the 30C heat of summer. Since replacing relays and this splice, no issues in over a year. A total of $75 that you can easily do yourself. 99% of mechanics and the idiot dealers will NOT find this. The incompetence is staggering.