My 1999 Subaru has starting to dim the headlights at night when accelerating at higher rpm's then act normal after the gear shift.  The headlights will also go back to normal if I lift off the accelerator. Automatic transmission and a new battery.  Any ideas???

check all grounds, make sure they are clean and tight

otherwise, maybe have alternator checked out

 

Thank you for your thoughts.  I have checked all grounds.  Confusing why lights would dim when engine is at higher rpm’s.   

+1 alternator

alt belt may be slipping, or, much less likely, 2-crank pulley is delaminated.

if grounds are all good, yeah, leaning towards alternator.

there are many reasons why an alternator could fail and in various modes, too

any big chain parts store can test the charging system for you & most do it for free. Go get it checked out

why the new battery? and how old was the last one?

Bad batteries can kill alternators, bad alternators can kill batteries... the two are intertwined

 

Edited February 2, 20215 yr by heartless

Yep, I'd put a multi meter on the system (even just to the cigarette lighter plug) and see what it looks like while running and revving.

Use a paint pen or white out to draw a line across the face of crank pulley, then you can tell if the outer ring moves.

Check belt tension.

You have checked *all* grounds? And you are 100% confident all contacts are making good connection, and wires have good continuity? 

I checked all belts ,and grounds are good.  Battery was old and had damage to the positive terminal, cold MT mornings were a challenge to crank the car.  New battery definitely helped the cold cranking but the issue is still there.  Now I'm getting a charging indication on the dash when I let up on the gas.  Getting alternator checked and will probably replace.  Thanks for the suggestions.

Get a Subaru Rebuilt Alt!

Go to Subaru and buy an alternator. That year happens to be like $85 from Subaru instead of the normal $300-$600. Don’t buy the parts store garbage no matter how many warranty, brand, employee, or guarantee claims they have.

Thanks

Unfortunately Subaru doesn’t have this part available anymore.  

just tried SPFY.com wanted vin# but did a quick search on 25D engine and came up with the same info about availability

he suggested try junkyards

verify part/engine as 99 OB had three alternator options

Not sure but your unit might be rebuildable

some other member might confirm and offer instructions

Any good alternator/starter rebuild place should be able to refurbish the old one and make it better than any off the shelf unit would be. Might be a little more costly, but in the long run well worth the added cost.

yeah, you may need to get something in to hold you over temporarily, but i would have the stock one rebuilt and put it back in when done.

did this with my old 95 Legacy and it was so worth it. Still have the aftermarket one up on a shelf, lol

 

This is the kind of place you want to find.. https://www.generatorstartershop.com/

Edited February 9, 20215 yr by heartless

On 2/1/2021 at 8:30 PM, Richardb1 said:

Confusing why lights would dim when engine is at higher rpm’s.

Had the same problem with our 95. Turned out to be a cracked (carbon) brush. There are two of them that ride against the spinning commutator. Vibrations from accelerating would cause it to loose connection.

I took it apart and found the cracked brush so I took it to a local shop and got new brushes and bearings. Worked fine after that.

www.car-part.com a good search engine.