2009 Mazda 5 - Dead battery, checking dark current

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2,164
Location
Winnipeg MB CA
Hello all - I'm looking for some auto-electric advice.

Our 2009 Mazda 5 stranded my wife yesterday, with a no-crank situation. Fortunately this was at home, and I answered my cell phone and was able to step her through finding the battery charger in the garage, popping the hood, using the prop rod, and hooking up the charger correctly. Trickier than it sounds, as the 5 has a plastic cover over the battery, and the charger, an old Schumacher, has options for amperage (0.3 A, 2 A, 10 A, and 50 A) and time (OFF, HOLD, and TIME [which is selected by a dial]). Anyway, she did great, and got the engine started fine.

She ran the charger on the 10 A setting for about 10 minutes, and then boosted the battery with the 50 A setting, which worked. Coming home, the car started fine.

So this afternoon was troubleshooting day for me. I charged the battery (10 A with the Schumacher for a few hours, and then switched over to the onboard NOCO Genius 1100 [1100 mA]) overnight, and then load-tested it a few minutes ago. Used my old Schumacher low-tech load tester - it's basically a resistive element with an analog scale. The battery tested fine - it stayed in the green during the 10 s load test, and stabilized after a couple of seconds.

I had figured the battery would be good - it's an AGM, and I replaced it only about 2-1/2 years ago. The factory battery was still working well, but was nine years old, and had tested marginally. The battery is branded as a Canadian Tire Eliminator, but I don't know the manufacturer.

But anyway, I assume it must be the dark current dragging the battery down. So I disconnected the positive battery terminal from the positive battery post, and used a trusted DMM set to DC Amperes in series between the two. Nothing at all! I expected at least 30 mA, but got nothing.

I must be doing something wrong, but am not sure what. Thoughts?

Thanks in advance!
 
Messages
26,373
Location
MA, Mittelfranken.de
Leave a door, trunk open or interior lights on and check to make sure you get a current draw. That will at least eliminate your setup.
Use the neg cable (it is safer) and set the amp meter to A not mA and the cables are not in the ohms position on the meter.
 
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565
Location
Canadia
My first suspicion would lead to something along the lines of what JRed suggested. Tough to know without seeing if the battery goes dead again.

As for diagnosis, I would wonder if the sequencing of inputs and connectivity was close enough to whatever happened before the battery went dead. In other words, before the car went dead, things probably went something like: Drove car-->Car in park-->Key off/out-->Open door-->Close door-->Lock doors(?). In testing, it presumably went more like: Car already parked-->Hood opened-->Battery disconnected-->DMM applied (for how long?). Based on those differences, maybe the power-thieving item wasn't "awake"?

Perhaps you could try taking a voltage reading from the battery, leave it parked as close to normally as possible, then take subsequent voltage readings to see if the battery is being drawn down?
 

Number_35

Thread starter
Messages
2,164
Location
Winnipeg MB CA
Thanks for the feedback so far, everyone.

I checked my DMM against a cheap old analog meter, which pegged at 250 mA. Unfortunately, that was its highest scale.

Went back and tried my DMM - still nothing.

Revived an older DMM by replacing the 9 V battery, and it's showing 290 mA!

Unbolted the lead feeding the underhood fuse/relay panel, and the current dropped to 0.

Tapped on all the relays without any change. Am now pulling fuses and relays one at a time.

To be continued!

@Trav, thanks, good thought, will switch to the NEG terminal. Don't want to do any arc welding!
 

Number_35

Thread starter
Messages
2,164
Location
Winnipeg MB CA
Dark current stayed at 290 mA (0.29 on my meter) until I pulled a 15 A fuse labeled "ROOM".

No idea what that means - time to find a schematic!
 
Messages
26,373
Location
MA, Mittelfranken.de
I found this..

ROOM fuse is a 15A that is marked as controlling the Overhead lights, Map lights, & Luggage compartment light. It also has some portion of the Power Door control, as it's the fuse that you pull to reset the Power Doors if necessary.

It seems it may also control the interior lights. Look at it in the dark, sometimes a glove box light is not going off due to a bad switch or some such thing.
 
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166
Location
Virginia
Meter - my thoughts were lead position on first read, often must be moved to pick up fuses, next.
Then there's fusea - often there are 2 fuses for amps in a meter - say a .5 and a 10 amp.
Room would be cabin, doesn't narrow much, but other fuses may rule out heated bits, stereo, air bags, power seats, etc. - maybe even a sub panel?
 

Number_35

Thread starter
Messages
2,164
Location
Winnipeg MB CA
Meter - my thoughts were lead position on first read, often must be moved to pick up fuses, next.
Then there's fusea - often there are 2 fuses for amps in a meter - say a .5 and a 10 amp.
Room would be cabin, doesn't narrow much, but other fuses may rule out heated bits, stereo, air bags, power seats, etc. - maybe even a sub panel?
Found a wiring diagram online. ROOM feeds various things including the body control module (BCM), which then feeds a bunch more stuff.

I guess from here I disconnect stuff and check for the dark current to drop off, and narrow it down from there.

I was hoping for an interior light, but no joy.
 
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3,392
Location
USA
290 mA is almost exactly what a #194 bulb uses. Did you check the glove box, trunk, etc?

After the battery has been hooked up for a while and you think the car is "dark", open the compartment in question and feel the lamp. If it is already warm or hot it's been on the whole time.
 

Number_35

Thread starter
Messages
2,164
Location
Winnipeg MB CA
290 mA is almost exactly what a #194 bulb uses. Did you check the glove box, trunk, etc?

After the battery has been hooked up for a while and you think the car is "dark", open the compartment in question and feel the lamp. If it is already warm or hot it's been on the whole time.
I was hoping it would be a bulb, but apparently not - the four interior lights are off, and there's no glove compartment light.
 
You need to check for the sleep mode. If you have clips, hook up your meter, then let it sit for an hour without touching the car, doors closed. Some cars will then go into a sleep mode and the parasitic current goes back to a low level such as 50 mA.

If it does, then it’s your battery that is the problem.
 

Number_35

Thread starter
Messages
2,164
Location
Winnipeg MB CA
Make sure you haven’t blown the fuse for the DC amp portion of your multi meter.
Will check that - that meter was my favourite.

You need to check for the sleep mode. If you have clips, hook up your meter, then let it sit for an hour without touching the car, doors closed. Some cars will then go into a sleep mode and the parasitic current goes back to a low level such as 50 mA.

If it does, then it’s your battery that is the problem.
The car had been sitting for quite a few hours at that point, so it should have been in sleep mode, unless having the hood open affects it.

The are a few threads out there with various Mazdas of this age having parasitic current draw through the ROOM fuse, so I think it's a legitimate problem. Some even report the same 290 mA current reading. No definitive solutions are reported, unfortunately.
 

Number_35

Thread starter
Messages
2,164
Location
Winnipeg MB CA
By the way. You can always put your cell phone on the record mode and place it in a closed trunk or glove compartment to record if a light is one.
Good thought! In this case, the body style is microvan with hatch, and there's no glovebox or underhood light, so I don't think I'm missing any lights.
 

Number_35

Thread starter
Messages
2,164
Location
Winnipeg MB CA
This may be part of the problem - or may be a complete red herring.

Per the OM, the security system is armed:

1. When the key is removed from the ignition, the doors, liftgate, and hood are closed, and

2a. the doors are locked either from outside remotely by the key fob, or

2b. the doors are locked by pressing the LOCK button on the driver's door before closing the door.

On my car, the system arms as soon as the key is removed from the ignition. The doors do not have to be locked. (I don't know whether the system is actually armed, but the red security icon on the dash flashes once every 2 s, indicating that the system is armed.)

Per the OM, the security system can be disarmed by:

1. Unlocking the door with the key. Nope, security icon continues to flash.

or

2. Pressing the unlock button on the transmitter (key fob). Nope, security icon continues to flash.

or

3. Inserting the key into the ignition switch and turning it to the ON position. Yes, the security icon goes out, and the car starts fine. The security icon does not come on while the car is running.

This all makes me wonder whether a malfunction in the security module is causing the system to draw more current when armed than it should.

Just speculation on my part. Thoughts?
 
Messages
3,392
Location
USA
It's probably set up to flash all the time while the car is parked, since that alone might deter some of the dumber burglars. It's an LED it uses basically no power.
 

Number_35

Thread starter
Messages
2,164
Location
Winnipeg MB CA
It's probably set up to flash all the time while the car is parked, since that alone might deter some of the dumber burglars. It's an LED it uses basically no power.
When it's functioning correctly, I agree. My concern is that it may be malfunctioning and drawing more current than it should.

I guess I need to start taking the centre console apart and disconnecting things per the schematic to trace the "leak".
 

Number_35

Thread starter
Messages
2,164
Location
Winnipeg MB CA
Make sure you haven’t blown the fuse for the DC amp portion of your multi meter.
Thanks, that was it. Was able to use it for DC current today after replacing the fuse. (I hadn't realized that the fuse was only to protect against overcurrent - I'd figured that if the display was good, the fuse was good.)
 
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