[BAJ716]

Suddenly my wife's 2005 Outback Wagon 3.0 VDC, 82k miles (yes, 82k, that's not a typo) is eating batteries.

I've been swamped at work but finally got around to putting a meter in series and checking the mA draw with the car off and pulling one fuse at a time.

In the engine compartment fuse box, fuse #8 "Backup Lights" is pulling 130mA with the car off (it's in Park not Reverse and the backup lights are off too). I can find no other lights on in the car. Anybody know what other devices may be wired to this fuse?

Thanks,
-Brad

 

[walker]

rearview mirror is listed, as is an "OP Connector". The OP connector seems to be for a harness to attach aftermarket stuff - unless you (or someone) tapped into it for a radio or something - like to toggle a rear view camera) it shouldn't be used.

op connector

Wiring schematic...

 

[BAJ716]

Thanks! We did buy the auto-dimming review mirror from the dealer shortly after we bought the car (new), which I'm sure draws something. Seems odd that if it were as high as 130mA that it wouldn't be tied through the ignition switch though. We haven't made any other changes to the vehicle, so unless it came from the factory with something connected to the OP, there shouldn't be anything connected there.

 

[plain OM]

In the engine compartment fuse box, fuse #8 "Backup Lights" is pulling 130mA with the car off (it's in Park not Reverse and the backup lights are off too). I can find no other lights on in the car. Anybody know what other devices may be wired to this fuse?

"car off" meaning ignition switch at Off, key out, and all switches/light controls etc Off?

As the wiring diagram above shows, the back-up lights etc are powered through fuse #18 in the cabin fuse box. Fuse #18 is powered only when the ignition switch is at On.

Fuse #8 (20 Amps) in the engine compartment fuse box isn't for the back-up lights. (It's a translation issue.) Rather, fuse #8 is an always-on "backup" power source. It supplies:

Auto A/C control module
Body integrated unit
Interior light
Spot map light
Audio
Clock
Keyless entry control module
Step light LH
Step light RH
Luggage room light (Wagon model)
Trunk room light (Sedan model)

 

[BAJ716]

"car off" meaning ignition switch at Off, key out, and all switches/light controls etc Off?

As the wiring diagram above shows, the back-up lights etc are powered through fuse #18 in the cabin fuse box. Fuse #18 is powered only when the ignition switch is at On.

Fuse #8 (20 Amps) in the engine compartment fuse box isn't for the back-up lights. (It's a translation issue.) Rather, fuse #8 is an always-on "backup" power source. It supplies:

Auto A/C control module
Body integrated unit
Interior light
Spot map light
Audio
Clock
Keyless entry control module
Step light LH
Step light RH
Luggage room light (Wagon model)
Trunk room light (Sedan model)

Thanks, that makes a heck of a lot more sense. I grabbed the fuse descriptions from here:

Fuse Box Diagram Subaru Outback (2005-2009)

Fuse box diagram (location and assignment of electrical fuses) for Subaru Outback (2005, 2006, 2007, 2008, 2009).

fuse-box.info

I guess I should have confirmed the descriptions elsewhere. I also notice now that I added an "s" above, it says "Backup light" not "Backup lights" for Fuse #8 in the engine compartment.

And by "car off", yes ignition off, keys in the house, all doors closed and all lights off.

The total parasitic draw is 275mA, so something is up.

I did the fuse-pulling test on the instrument panel fuse box and found that:
-Pulling fuse #6 INCREASES current draw, it was +50mA and climbing when I replaced it
-Fuse #7 is drawing 100mA
-Fuse #27 is drawing 100mA, but when I replaced it my meter showed a value 147mA LOWER than the current before I pulled fuse #27. I suppose something could have reset and I wasn't exactly patient about waiting to see what would happen. But the current draw did not change while I pulled and replaced the rest of the fuses, #28-33.

I did do the cabin test with the door open, I turned off dome light but the lights in the bottom of the doors were still on. I had 763mA at that point. I was getting cold and rather than figuring out how to disable those I assumed I could just take differential readings, but maybe I was assuming something I shouldn't have, since I tallied up 330mA with the door open and only showed 275mA at the battery with just the hood open. When I finished and closed the door the meter was right back to 275mA.

 

[plain OM]

Fuse #27 is drawing 100mA, but when I replaced it my meter showed a value 147mA LOWER than the current before I pulled fuse #27.

Are you sure about the fuse number? This is a bit tangential, but fuse #27 supplies the main power for the heater fan motor, through the blower fan relay switching contacts. If the relay contacts stick closed ("on") when the ignition is off (rare, but not impossible), power would be sent to the motor, and it's possible a small current will flow, although perhaps not enough to cause the fan to noticeably run. BUT, what is odd is that the supply to the relay contacts is through both fuse #27 and fuse #28, with the two fuses in parallel. If both fuses are good, and the relay contacts are erroneously closed, pulling one fuse while the other is still in place shouldn't cut the supply to the motor. So the drop of 147 mA when fuse #23 was pulled is puzzling, unless fuse #28 is blown or its contacts are bad.

That car probably has the automatic HVAC with the 6 CD changer audio system. Fuse #8 (engine compartment) provides "backup" power to both. Perhaps try disconnecting these at their connectors in behind to see if that corrects the excessive dark current (parasitic draw).

 

[BAJ716]

You are correct, it was not #27 it was #26 (power window relay?). I was pulling fuses in sequence and only writing down the ones that changed the reading on the meter. I had made hash marks on my printout as row references and I got off by one. I know it was at the end of the row and because I did not pull the fuse before it (#25 SRS airbag system (Main)) as it was different in that it has molded tabs on the sides of the fuse block base, like maybe Subaru was saying "caution/don't pull this one" or something. I made extra notes because of the 147mA shift in the reading from before I pulled #26 to after I plugged it back in.

 

[plain OM]

Fuse #26 provides power to the energizing coil (not the main switching contacts) of the power window relay and the main fan relay 1. When the ignition is Off, and everything shut down, there should be no power to fuse #26.

 

[BAJ716]

You are correct, it was not #27 it was #26 (power window relay?). I was pulling fuses in sequence and only writing down the ones that changed the reading on the meter. I had made hash marks on my printout as row references and I got off by one. I know it was at the end of the row and because I did not pull the fuse before it (#25 SRS airbag system (Main)) as it was different in that it has molded tabs on the sides of the fuse block base, like maybe Subaru was saying "caution/don't pull this one" or something. I made extra notes because of the 147mA shift in the reading from before I pulled #26 to after I plugged it back in.

Fuse #26 provides power to the energizing coil (not the main switching contacts) of the power window relay and the main fan relay 1. When the ignition is Off, and everything shut down, there should be no power to fuse #26.

Thanks. I'll double-check that one, but it sounds like I may be narrowing down at least part of the problem.