Subaru Outback Forums banner
  • Hey everyone! Enter your ride HERE to be a part of this month's Outback of the Month Challenge!
1 - 19 of 19 Posts

·
Registered
2006 Outback LLBean Edition
Joined
·
18 Posts
Discussion Starter · #1 ·
2006 LL Bean with about 172k.

Drove a couple miles up the road today and the battery light came on when I was about to pull in to my destination. Lights, AC, and radio were running at the time.

Turned the car off, ran my quick errand, and then started the car. Battery light was no longer on. Then proceeded to drive two 10 mile trips without the light coming on.

Stopped by the local auto parts store to test the battery and alternator, and they both came back as good. Was also inspected in PA about a month ago and everything came back as fine.

Is there anything that could have caused the light to briefly come on like this? I'll be taking this car on a 350 mile trip this weekend and want to come up with a backup plan if necessary.

Thanks!
 

·
Registered
2005 3L LL Bean Outback
Joined
·
307 Posts
These are the 4 documented conditions for which the generator (alternator/dynamo) would generate cause a charge/battery warning light:

516893
 

·
Registered
2006 Outback LLBean Edition
Joined
·
18 Posts
Discussion Starter · #3 ·
These are the 4 documented conditions for which the generator (alternator/dynamo) would generate a charge/battery warning light:

View attachment 516893
Thanks for that!

The auto parts store test showed 13.89V with no load, and 13.79V when loaded, so I'm guessing #1 and #2 can be ruled out.

Since this is my first time that the battery light came on - does the battery light stay on and need to be "cleared" (kind of like an engine light), or does it only come on when an issue is actively occurring? Curious since it has not been on for the rest of the day.

Again, thank you all for the help!
 

·
Registered
2012 OB , 2017 Impreza
Joined
·
3,660 Posts
does the battery light stay on and need to be "cleared" (kind of like an engine light), or does it only come on when an issue is actively occurring?
Actively occurring.

-----------------------
I have seen occasions when the belt driving the alternator would slip (stop driving the alternator) for a few seconds. This usually happens within the first few minutes of starting cold engine, there are multiple electrical loads AND the driver makes a sharp turn (Power-steering pump adds more load on the belt). As the belt warms up... it gets 'sticker' and starts driving the loads.

This would fall under #1 on the above list (no voltage generation)

You may wish to verify the belt is in good shape and not getting loose.
 

·
Registered
2006 Outback LLBean Edition
Joined
·
18 Posts
Discussion Starter · #5 ·
Actively occurring.

-----------------------
I have seen occasions when the belt driving the alternator would slip (stop driving the alternator) for a few seconds. This usually happens within the first few minutes of starting cold engine, there are multiple electrical loads AND the driver makes a sharp turn (Power-steering pump adds more load on the belt). As the belt warms up... it gets 'sticker' and starts driving the loads.

This would fall under #1 on the above list (no voltage generation)

You may wish to verify the belt is in good shape and not getting loose.

Thanks!

I'll check out the belt since your example is pretty much the same conditions as when it occurred. May also explain why it didn't come on during my subsequent trips today
 

·
Registered
2005 3L LL Bean Outback
Joined
·
307 Posts
Wondering whether the condition produced a trouble code. Seems like P2503 could have been produced if the charging system had too low of a voltage. Not sure whether the CEL would (have to) come on as well.
 

·
Registered
2006 Outback LLBean Edition
Joined
·
18 Posts
Discussion Starter · #7 ·
Wondering whether the condition produced a trouble code. Seems like P2503 could have been produced if the charging system had too low of a voltage. Not sure whether the CEL would (have to) come on as well.
No P codes, but there was a C0107, C0108, and C0109 (I can't remember a time when the ABS light came on)
 

·
On the Super Mod Squad
2002 3.0 VDC Wag + 2018 2.5 Leg Ltd
Joined
·
26,960 Posts
No P codes, but there was a C0107, C0108, and C0109 (I can't remember a time when the ABS light came on)
your car can do this:

and get more / different than any hand held.
 
  • Like
Reactions: je513412

·
Registered
2006 Outback LLBean Edition
Joined
·
18 Posts
Discussion Starter · #9 ·
your car can do this:

and get more / different than any hand held.

That was actually how I pulled those C codes since my cheap handheld came up with nothing. Definitely saving the link for future reference!
 

·
Super Moderator
Outback 2011 3.6R Premium
Joined
·
2,455 Posts
I have had the battery light momentarily come on in a couple of vehicles when the alternator brushes were at the end of their life (worn down).

The solution was a new set of brushes or new brushes module.

In my experience Subarus alternators generally start giving trouble around 180,000 miles and yours could be another one that is due for a rebuild/replacement.

As you have a 3.0 H6 you have a specific model alternator. If you need to replace it DO NOT get one from an auto parts store as these are known to cause a multitude of problems in the H6 vehicles.

Seagrass
 

·
Registered
Joined
·
19,013 Posts
Does the BATT warning light come on at normal, full brightness, or sort of dim, perhaps varying in brightness? Also, does the BRAKE warning light glow or light up at the same time, and go off when the BATT light goes off?

When the battery and alternator were "tested", was the BATT warning light on, or off? (If it's an intermittent fault, it's not likely to test bad when the system is working.)

Do you have a multimeter that can be used to monitor the system voltage while driving, and especially when the BATT light comes on, perhaps connected to the accessory power outlet? Knowing whether the voltage drops down low, or goes unusually high, might help with diagnosis.

As mentioned, the H6 alternator is different from the H4 because of override control of the H6 alternator internal self-regulation function by the ECM. However, the ECM can only cause the alternator to lower its charging rate (voltage), not go above the internal regulator level. This adds factors to the diagnosis; consequently, knowing what's happening when the light is on could be a clue.
 

·
Registered
2012 OB , 2017 Impreza
Joined
·
3,660 Posts
Do you have a multimeter that can be used to monitor the system voltage while driving,
I found a voltmeter at WallyMart intended to plug into power-outlet (ciggarette lighter socket). It was under $10.

This is FARRR more convenient than using my $300 Fluke meter while driving.
 

·
Premium Member
01 VDC, 05 R Sedan, 06 BAJA EJ257
Joined
·
15,905 Posts
With the C codes on the system(s) I'd look at the grounding and battery clamps. Poor grounding will inhibit the alternator function and communications between the computers suffers. Just recently had a 2009 Legacy 2.5 Ltd in the shop with C0045 and a few battery related codes. The car has 98k miles and it was the battery cables causing the problems with the ABS/VDC system as well as communication with the TCM. New cables, everything went to normal.
 

·
Registered
2005 Outback Wagon 3.0 L.L. Bean
Joined
·
1,079 Posts
That car at that age has a horrible ground system. Start by replacing the braided ground straps that are likely hanging in shreds. Clean and reattach the other engine cable grounds.
 

·
Registered
2006 Outback LLBean Edition
Joined
·
18 Posts
Discussion Starter · #15 ·
Hi All, This is a new post but kind of a follow up to this post below. Unfortunately with the chaos of wrapping up work and packing, I missed a couple of the later replies.


Was driving from Western PA to Ocean City Maryland. Everything was fine with the car and we were stuck in traffic coming up to the Bay Bridge. Ended up putting the windows down and the Battery and Brake battery lights on the dash came on when they were put down. We were able to pull off in to a shopping center, and thankfully we had some family about 20 minutes behind us. We were able to go back and forth to the nearest auto parts store. Fast-forward about 5 hours and changing out the alternator, belt, battery, and a headlight bulb, and the Battery and Brake lights are still on and the alternator is not charging.

Ended up purchasing ANOTHER battery as a fresh backup to make it to Ocean City without any accessories on while we still had daylight. If you're keeping count, that means we had three batteries in the car - A new one under the hood, the old one (which was reading at about 12.5v and still starting the car), and another brand new one in case the previous two got drained. Made it to ocean city without incident. When we pulled in to our condo, the new battery under hood was drained enough to not be able to start the car without a jump (i believe it is reading about 11.7v).

So, does this sound like an issue with the grounding cables? An issue with the auto parts store alternator I bought? I am taking this to a shop in hopes it can be fixed prior to our departure, but am trying to get a better idea of what is going on.
 

·
Super Moderator
Outback 2011 3.6R Premium
Joined
·
2,455 Posts
As mentioned in the other topic, most auto parts store alternators are NOT compatible with the Subaru 3.0 H6 engine. The ECU controls the alternator output in the H6 vehicle and I believe this is the downfall of the auto parts store alternators. Many other members have had failures with auto parts store alternators and this is a very well known problem.

Try and find a genuine H6 alternator from an auto wrecker as it will probably resolve your problem.

Seagrass
 
  • Like
Reactions: cardoc

·
Registered
2002 Outback VDC
Joined
·
298 Posts
My alternator went at 172k. Swapped in a reman'd Denso and it only kind of worked, output would get a little low and battery light would come on. Thought the "new" alternator had to be fine and spent a while back probing voltages on connectors etc, learned a lot. It turns out the reman'd alternator was a dud. I sent it back and went with one from DB Electrical, has been great so far.
 

·
Premium Member
01 VDC, 05 R Sedan, 06 BAJA EJ257
Joined
·
15,905 Posts
I'll tell you this much - Part store alternators are for the H4 and will either not work or overcharge the system. They list them the same because they look the same, plug up the same, and have the same number of wires. They are not the same.

An alternator from Subaru is $$$$.

Go with DB or find a salvage one from an H6.
 

·
Registered
2005 3L LL Bean Outback
Joined
·
307 Posts
Probably don't just surrender your old alternator to a parts store. Assuming it's OEM it could still have some value for refurbishing as they go for ~ $500 new ($ 300 if you roll the dice on ebay).
 
1 - 19 of 19 Posts
Top