SpinningNacho

Quirk: Battery seems to drain faster than I'd expect when my RX8 is sitting. If I forget to hook up my trickle charger the battery is dead in a week or less.

Steps: Hooked up my new DMM to monitor the drain on the battery when the car is off. Reading seems to average around .25, Started yanking fuses.

I removed all of the fuses in the interior fuse box, and most of the ones in the engine bay fuse box one at a time (didn't pull some of the larger fuses related to the engine) and didn't notice much of a difference in the reading.

I did notice that after closing the driver's door the reading would drop close to 0 and hold there for about 30 seconds. After that it would jump and stay back around 0.25. Sometimes I feel like I hear a click around when the reading spikes, but its not loud enough for me to guess where its coming from.

Based on that, it seems related to the security or keyless system? But I am not sure how to troubleshoot it further. I have read a few threads on here and the keyless system being hard on the battery doesn't seem uncommon, but if I am interpreting the scale on the DMM then the drain I am seeing seems much higher than expected (25-50ma). I don't really see a fuse or a relay that is documented as feeding the keyless system that maybe I didn't pull.

It's not the end of the world and I already make a habit of keeping it on a tender, but I guess at this point I'm just curious to pinpoint it down if I can.

Loki

iTrader: (1)

Normal draw is around 10-15 milliamps so something is definitely up. Trunk light? It's not uncommon for it to stay on after closing the lid, you can peek through the center divider.

Dropping to zero after closing the door is weird.. what about the ceiling lights?

SpinningNacho

Agree that something seems off.

I can't find any lights stuck on, and I figure that the lights would all be on one of the fuses I pulled during my checks. 10-15ma seems very low for a car equipped with the keyless system. I can't find the page in the manual right now, but I know there is a separate spec for cars that have AKE and its higher than the normal 10-15ma.

This thread has a lot of good information (https://www.rx8club.com/rx-8-discuss...le-off-237422/) but nothing concrete. Lots of people reporting 50ma-150ma draw with the stock electronics.

It seems like there is some activity that the security or keyless system does, that paused shortly after closing the door momentarily. Honestly even with my door open the current draw is in the 75ma range which is lower than the reading with the door closed once the power drain kicks in. I'll keep poking around. Maybe I will take the glovebox out and see if I can unplug the AKE modules so I can see if anything changes.

SpinningNacho

So, I got a normal multi meter and one of the fuse probe attachments as well to use instead of my DC clamp meter.

I see the ~0.3A draw if either the D. Lock fuse or the Room fuse are connected. Only when both are removed does the constant drain seem to stop.

I did verify again that none of the interior lights are getting stuck on. Checked the trunk light through the divider, and even double checked the visor lights since I know those do weird things sometimes.

I know something in the bose unit gets power from the room fuse since I can hear it kick on when connected (sounds like a cd changer) so I even tried unplugging the radio completely, but it had no effect. Also tried unplugging the rear view mirror since that was easy, but it also didn't make a difference.

I went reading through a lot of similar threads for the early NC Miata figuring the systems are probably somewhat similar. It seems like for the Miata ~250ma-300ma is what the drain is until the car has been left along for around an hour, after that the electronics should go into sleep mode and the draw should fall to ~30ma. Even after an hour I was still reading a 0.25 draw.

In some cases this issue has been tracked down to the hood switch being faulty and keeping the security system from sleeping, and possibly keeping the ECU in a diagnostic mode. I think that will be the next thing I check since my power drain seems inline with what is expected before the security system and ECU fall into the sleep mode, and the D Lock and Room fuse being involved also seems to point that direction.

(As part of my original troubleshooting I kept the hood switch engaged by closing the hood latch with a screwdriver)

TLDR; I think my RX8 has insomnia

Ricky SE3P

iTrader: (10)

Try disconnecting the bose door amps and see what happens. IIRC they do get a constant 12v line and if something is turning faulty internally in them, they could just be keeping powered up but not outputting d/t lack of any signal from the headunit. You can maybe try the same with the trunk bose amp. Also maybe check your lights in your visors? Maybe they are staying on for some strange reason causing a very small drain? I dont know, just throwing shots in the dark.

SpinningNacho

I did check the visor lights and they seemed fine. My car is pretty low miles and the visors are still in pretty good shape.

I didn't notice a difference when I pulled the Audio fuse by itself, but unsure if the door amps have additional power that doesn't come through that fuse. Will have to go back and look at the diagram again, but I wouldn't think they'd tie to the room or d. lock fuse circuits.

I know the trunk amp gets a turn on signal from the radio (which when unplugged didn't make a difference) but it does have its own power connections. I'll check that on the diagrams as well, but would also be surprised if it pulls from the room or d. lock fuse. The only overlap between those two circuits that has jumped out to me so far is the keyless/security system.

Loki

iTrader: (1)

In my case it was the headlight washer motor. No idea why, maybe it had an internal seal breach that coupled electricity to body somehow. It can be really weird stuff.

Room is a whole bunch of stuff including engine electronics. Possible there's an aftermarket attachment somewhere? An alarm or remote starter or gauges or an OBD device?

SpinningNacho

Hmmm. There's not much aftermarket that I have put in currently. I have a dashcam but it taps the accessory fuse, and I have been keeping it unplugged while testing.

Other than that, I have aftermarket tweeters and rear speakers but they are just connected to the OE wiring/amps. ie its the OE Bose system except for those speakers.

I do keep a bluetooth OBD device in the car, but I don't keep it plugged in since I have made that mistake on previous cars. No aftermarket gauges. No aftermarket alarm or other devices that I am aware of, but I am the second owner. If its there, I haven't ran across it in the last 3 or 4 years

This is what I see on the diagram. Not sure how to best isolate some of the remaining items if the hood sensor doesn't end up panning out, but will cross that bridge if I get there.

Room

Engine Control System
Instrument Cluster
TPMS
Daytime Running Light System (No running lights stuck on that I see)
Heater and Air Conditioner
EC-AT Control System (Has manual, not automatic)
Rear Window Defroster (Unless something is seriously wrong, the rear defrost definitely doesn't seem to be stuck on)
Trunk Light
Courtesy Light
Interior Light
Map Light
Vanity Mirror
Illumination
Audio System/Car Navigation System
Keyless Control Module
Dimmer Mirror
Data Link Connector (Nothing plugged into OBD port)



D.Lock

Keyless Control Module
Sliding Sunroof (Haven't unplugged it yet, but it seems to work as expected)
Power Seat (Haven't actually unplugged it yet, but its not doing anything odd)
Accessory Socket/Trunk Lid Opener (Nothing plugged into acc socket, trunk opener seems to work fine)

speedieone

I would recommend the tried and true pull the fuse method. Here is a link to a very early Eric the Car Guy video showing how to do it.

SpinningNacho

Another update

Re: Hood latch
Tested my hood latch per the service manual. Haven't decided what to think about it yet as it seems to test the opposite of what the manual calls for.

Manual says when the hood is open the switch should have continuity, and that when the hood is closed it should not. I believe this matches with other sections of the manual that mention that the line to the keyless module for the hood latch should be 5v when open and less than 1v when closed.

When I unplugged the switch and tested, I was seeing no continuity when the hood is open, and continuity when it is closed. I'm putting a pin on this one to revisit soon as I reconnect all of the electronics.

But that leads to a second finding where I was just the big dumb. When I removed anything aftermarket except for my dashcam, my OE navigation hood didn't register to my brain. Its been there long enough that I don't even think about it. My car did not come from the factory with navigation and I added the hood after the fact. What I have found now is that for whatever reason the hood draws ~0.15-0.2 amps continuously.

The hood only has 4 wires (Acc, +12v Bat, illum, and ground). There's no shorts in any of the wires according to my meter. I don't know the stock behavior but I have always noticed that the hood can be raised and lowered even when the car is off. I did double check yesterday and the Acc and +12v Bat aren't connected backwards or anything. I have no idea if this is normal for the hood or not. I lean towards not since my car didn't used to drain the battery so fast even with the hood installed....this started fairly recently.

For the time being I ran a second Acc line and left the +12v bat disconnected (and shrink tubed to avoid any unfortunate events). This prevents the position memory from working which prevent the hood from opening automatically but I can live with that. Long term I will probably put it back on +12v bat with a toggle switch so that I can turn it off if I know the car will be sitting for a while.

Short of replacing the factory PCB with another OE unit or something like an Arduino for rise/lower motor operation, I don't have the faintest idea how to actually solve the constant power draw from it. I only have the factory PCB there for the motor and open/tilt buttons and in no reality does that kind of draw make sense just for keeping its memory alive.

With that taken care of, the backup current has been reading 0.02-0.07 so far, which is close enough to the normal range (its at least on the correct scale now). I still need to reconnect the keyless control module in the passenger kick panel though. Once I do that, I should be able to figure out what effect (if any) the readings I saw on the hood latch are having. Knock on wood that the current doesn't spike back up when the module is reconnected (or if it does, it's just due to the hood latch).