Jump to content

Welcome to Ultimate Subaru Message Board, my lurker friend!

Welcome to Ultimate Subaru Message Board, an unparalleled Subaru community full of the greatest Subaru gurus and modders on the planet! We offer technical information and discussion about all things Subaru, the best and most popular all wheel drive vehicles ever created.

We offer all this information for free to everyone, even lurkers like you! All we ask in return is that you sign up and give back some of what you get out - without our awesome registered users none of this would be possible! Plus, you get way more great stuff as a member! Lurk to lose, participate to WIN*!
  • Say hello and join the conversation
  • Subscribe to topics and forums to get automatic updates
  • Get your own profile and make new friends
  • Classifieds with all sorts of Subaru goodies
  • Photo hosting in our gallery
  • Meet other cool people with cool cars
Seriously, what are you waiting for? Make your life more fulfilling and join today! You and your Subaru won't regret it, we guarantee** it.

* The joy of participation and being generally awesome constitutes winning
** Not an actual guarantee, but seriously, you probably won't regret it!

Serving the Subaru Community since May 18th, 1998!

Guest Message by DevFuse

- - - - -

Flickering/dimming lights on 1996 Legacy L


  • Please log in to reply
4 replies to this topic

#1 suburman



  • Members
  • Pip
  • 3 posts
  • Worcester, MA

Posted 23 February 2014 - 03:20 PM

I have a '96 Legacy L wagon.  Lately, we've noticed that all the lights (headlights, dash lights) briefly dim and brighten.  There it no pattern, just a brief dip in brightness, usually once every few seconds.  I figured likely alternator or voltage regulator, less likely the diode.  I took it to the shop and they said the voltage was fine, alternator and diode seemed fine, and it was going to require disconnecting things till they found the problem.  I didn't like that idea much and needed the car back for the next snowstorm.  All the lights dimming said to me it had to be an overall voltage drop and, sure enough, my VOM showed voltage dipped to about 12.9V from ~14.2 whenever the lights dimmed.  With an OBD2 reader, I can see the voltage briefly spike downward.  It never goes above about 14.5V, making me think the regulator is ok.  Revving the engine makes no difference.  However, I found that with enough electrical load (e.g., the headlights on AND the fan on full speed (but not half speed) or the rear defogger also on and the fan at half speed, the spikes disappear and the voltage sits steady around 13.5V.  Grounding and connections between the alternator and battery are fine.


Anyone run into this?  I was ready to buy an alternator, figuring maybe the brushes were going bad, but the discovery that enough load stopped the spikes made me wonder if it was the regulator, after all.


(And can someone tell me where the stupid regulator is located?  Google isn't helping and it does not seem it is in the alternator like in many cars - in fact, it costs much more than a rebuilt alternator.)


Many thanks.

#2 jp98


    USMB Regular

  • Members
  • 268 posts
  • Gypsum, Co

Posted 23 February 2014 - 04:39 PM

I had it happen on my 98 Outback.  The problem was the alternator but everything tested fine on the bench.  Whenever the RPM's would reach 2300 RPM's the alternator would cut out but keep it below that and everything would work fine.

#3 suburman



  • Members
  • Pip
  • 3 posts
  • Worcester, MA

Posted 23 February 2014 - 05:39 PM

Thanks!  My problem's a little different - just quick voltage dips to ~12.9V every few seconds, regardless of RPM (well, actually seems to occur more rapidly when revving the engine); battery seems fully charged.  Hunting around more, it seems the voltage regulator is inside the alternator, so I think I'm just going to get a remanufactured alternator and put it in, given how easy that appears to be.  Cheaper than paying the shop to dig around for an hour or two and then say it's the alternator (unless someone tells me it's likely to be something different here).  I don't understand why, when loaded so that the voltage hits about 13.5V, the drops disappear and the voltage stays absolutely level.

Edited by suburman, 23 February 2014 - 05:42 PM.

#4 Fairtax4me



  • Members
  • 12,342 posts
  • Charlottesburg, VA

Posted 25 February 2014 - 12:54 AM

Regulator is built in. That's what you plug the wires into on the back.

Make sure battery terminals are clean. Make sure the cable end on the alternator is clean and tight. If connections check out, Subaru sells remanufactured alternators for that car for around $80.

#5 suburman



  • Members
  • Pip
  • 3 posts
  • Worcester, MA

Posted 28 February 2014 - 07:04 PM

With a new (well, rebuilt) alternator, the problem is fixed.  No voltage dips/dimming lights, and the voltage doesn't even drop down to 13.5V with full load now.  Thanks, folks, and I hope this helps the next person who runs into this one.

Also tagged with one or more of these keywords: electrical

0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users