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Discussion Starter · #1 ·
I have a 1999 LOB 2.5 with a 2 month old batter and a week old alternator. Been driving great for last week and a half with no issues, this morning I started her up and let her warm up before work, made it about 5 miles and batt light came on, then lost radio then lost tach and speedo, then all lights went dim and all other warning lights came on trans started jolting and engine was surging like no fuel or intermittent fuel. Barely made it in the drive and it died and wouldn't try to start, where should I start looking? Does computer control alternator on the h4? Or is the charging system an independent system (regulates itself)? Is the main alternator/battery fuse or fuseable link in main box? No corrosion on battery or plugs for alternator. Going to look after work any help would be appreciated!
 

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(formerly) 03 H6 OBW , (presently) 06 WRX Sportwagon & 2021 Honda CR-V
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if the alternator is a typical parts store rebuilt, they are known to be very poor risks and unreliable. I might begin by jump starting the car and getting a voltmeter across the battery, or charging the battery, starting the car and checking charging voltage - should be over 14V. maybe with someone holding the revs at 1000rpm, voltage could be 14.4 or a little more. NOT 12.4 nor 16.4

or, just take the alternator and the battery back to where you got them and have them bench tested.

to me, alternator is highly suspect. Double check easy things like tight cable connections to battery posts, good connections to alt., and good accessory belt condition too.
 

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I thought the answer to your problem is in your post, “a week old alternator” which I read as “a weak, old alternator”. Now that I realise you have a new alternator that is only one week old then I also suggest you go back to where the alternator and battery were purchased and get them to test them.

From memory that model alternator has a built in regulator pack and output is not controlled by the ECU

Let us know how it works out.

Seagrass
 
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I agree with the above appends..... A typical autopparts-store alternator is poorly rebuilt and prone to failure. This is WHY they have a 'lifetime' warantee. They are glad to hand out new ones to you over the counter every time YOU Remove/Replace it.

It is FAR better idea to go to scrapyard and get a REAL Subaru alternator. The last time I was at local scrapyard, I saw a shelf labelled "Subaru" with 100s of alternators on it. (Subaru is every 3d car on the road here in VT so there are many of them in the scrapyards which have rusted out)
 

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Discussion Starter · #6 ·
So I hooked a volt meter to my battery and it was putting 14.5v but when I run a test through my obd2 it fails and says 12.67v also throwing a p1540 code but NOT the p0500, I know sometimes they pull together but I just have the one, idle is at 750-800rpm, speedo doesn't work but everything else has come back on and battery light is off for now...
 

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Sounds like you have poor battery or ground connections.

If you have 14.5v at the battery with the engine running and 12.67 elsewhere you have a voltage drop typically caused by a corroded or faulty connection. This is also backed up by your symptoms now having disappeared.

Seagrass
 
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Discussion Starter · #8 ·
Seagrass, all visible connections at alternator at battery in fuse panel are all good no corrosion or "burnt" coloration on fuseable link. Where else should I check? Bad harness? I'm at a loss, do you think my code for speed sensor would be tied into my volt issue? Sorry im new to subaru's and just trying to find subaru known causes.
 

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Subaru’s have multiple ground connections and these need to be free of corrosion for all systems to work as designed.

There are around five or more in the engine bay, one from each head to chassis, main earth strap from battery to starter, one or two on the inlet manifold etc.

You can use a multimeter on OHMs setting to test from each of these points back to the battery negative post. All readings should be less than 3 Ohms, if they are higher than there is a problem somewhere that you need to find.

Seagrass
 

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Discussion Starter · #11 ·
@seagrass i started testing everything and got good readings on grounds sometimes alternator would charge at 14.5v then at times it wouldn't charge at all got looking closer at my belt and all ribs are separated, even with the alternator spinning would that really cause that big of charging issues?
 

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That belt could easily be the cause of your intermittent problem.

Change it for a new one and see if your problems are gone.

Seagrass
 
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