2010 Mazda6: Random, infrequent parasitic battery drain (Dealer service, local mechanic can't find problem)
Alarm started going off randomly several years back when parked (car undisturbed -- only WE were). Sometimes days apart, sometimes weeks, even months from one event to the next.
After it seemed more than a one-off issue, took it to the dealer -- couldn't find the problem
Several years later, took it to highly-regarded local mechanic (Fincher's Auto Service), who kept if for up to a week to see if alarm would go off (it didn't); scans didn't turn up anything. The only thing found was an aftermarket alarm system, which Fincher's removed with my permission. Car worked fine for 3+ more weeks, and then alarmed again.
Problem does not seem related to how long since the car has been driven -- recently it happened twice: the day after my wife drove the car 190 miles to her sister's; the alarm went off both in the morning after arrival, and again around midnight. After returning home, it didn't occur again until several weeks later
I subsequently noticed that the first indication of a problem is that the courtesy lights on the external mirrors will light up without any nearby key fobs (the second photo shows battery level at 11.98v after I noticed lights, no alarm at that time); battery does not appear sufficiently drained for that to occur(?)
I've measured currents via voltage drop across fuses and haven't seen anything extraordinary there.
I've lubricated door, trunk, and hood latches with lithium grease -- doesn't seem to have an (lasting?) impact
A web search shows that LOTS of folks see this issue with their Mazdas, and I haven't come across a fix yet (other than either disconnecting the alarm or adding a battery switch). All the supposed, "Fixed problem" sites just point to generic battery drain sources and testing -- haven't found any that solve this random issue ( https://duckduckgo.com/?t=ffab&q=2010+Mazda6+battery+drain&atb=v231-1&ia=web)
Again, this issue occurs at random times, up to months apart, or within a week or two. As I write this, it's been at least 2 weeks with no issues
I'd like to see if this can be resolved, instead of resorting to a band-aid like adding a battery cutoff switch or removing the OEM alarm module (if that's even possible)
Here's a photo link to Battery, Charging System, and OBD2 images: https://postimg.cc/gallery/BSygz8j
Thanks!
Craig in Healdsburg
wanted to note - when my wife took the 190-mile trip to visit her sister, and voltage level was "OK" when checked by my nephew AFTER the alarm went off the first time.
You have to isolate the bad circuit by watching Scotty's video on "Parasitic Drain."
Thanks for your reply, Doc.
I've watched that video (
along with a number of others, and have measured for excessive voltage drops
Because the problem is random (not persistent), no excessive voltage drop (translating to excessive current draw) is observable
The mirror lights are suspect. Battery should not dip below 12V like that.
Thanks for responding.
The mirror lights, alarm, and battery drain are all symptoms of the problem (not the source) -- and probably in that order.
I say "probably" because the car may be find for weeks on end, going for even longer than a month without issues, and then randomly exhibit the problem.
Since the problem has been widely reported on the web, and the only "solutions" have been to isolate a (consistent) source of drain, I've given up on the "holy grail" solution and had my mechanic install a battery bypass switch so that neighbors don't get annoyed by the alarm going off. In the (unlikely) event that the car gets stolen, it's insured...
Other than the mysterious (sometime) parasitic battery drain, the car runs great
Quick recap: The alarm on my wife's 2010 Mazda6 would randomly sound off for no apparent reason, and/or the battery would drain to the point where the vehicle wouldn't even crank (the alarm, of course was a result of gradual battery drainage). When the problem occurred, it was usually overnight, undisturbed. I looked at a number of videos and tried (almost) all the suggestions, including all I could find here, and finally came across a video that clarified the solution (which can be played here:
The solution has been proposed previously, but what wasn't clear is that it's the switch mechanism, which is BELOW the door latch, and NOT inside the door latch itself that needs lubrication. In order to lubricate the hidden switch, you need to point the WD40 straw BELOW the latch mechanism and saturate the area with about 30-45 seconds worth of spray (followed by the usual repetitive open/close of the door to work it in).
Once I saturated the hidden switch, the problem appears to have been resolved (3 months and counting).
Definitely give this a shot before considering a door latch assembly replacement.
video doesn't work