The Subaru SVX World Network   SVX Network Forums
Live Chat!
SVX or Subaru Links
Old Lockers
Photo Post
How-To Documents
Message Archive
SVX Shop Search
IRC users:

Go Back   The Subaru SVX World Network > SVX Main Forums > Technical Q & A

Reply
 
Thread Tools Display Modes
  #1  
Old 01-02-2007, 03:29 PM
TomsSVX's Avatar
TomsSVX TomsSVX is offline
Maniac modifier
 
Join Date: Dec 2003
Location: Branchburg, New Jersey
Posts: 15,489
Registered SVX Classic SVX
Overcharging alternator

My 92 teal is having some weird issues. I get the christmas tree lights like the alternator was going bad, so I checked my voltage at the battery and at the alternator. I am showing 17.9v in both places... Here is where it gets interesting. When I hit the brakes, the lights go off like nothing ever happened but once I hit the gas again and get the rpms up, the lgihts on the dahs come right back up. Well, it doesn't look like I am losing charge, but it is over charging the system.. I figured the voltage regulator is shot and I ordered a new alt from a local pep boys... Anyone else have some insight??

Tom
Reply With Quote
  #2  
Old 01-02-2007, 03:57 PM
Hocrest's Avatar
Hocrest Hocrest is offline
Freezepop's are Awesome!!!!
Subaru Silver Contributor
 
Join Date: Oct 2003
Location: Pittston, PA
Posts: 5,334
Send a message via AIM to Hocrest
All those cars, engines and parts sitting around and no extra Alts??????
__________________
Dave
- 03 Baja - 92 SVX - 86 Brat - 08 OB 3.0
Reply With Quote
  #3  
Old 01-02-2007, 09:56 PM
Trevor's Avatar
Trevor Trevor is offline
Registered User
 
Join Date: Feb 2002
Location: Auckland, New Zealand
Posts: 5,223
Registered SVX
Quote:
Originally Posted by TomsSVX
My 92 teal is having some weird issues. I get the christmas tree lights like the alternator was going bad, so I checked my voltage at the battery and at the alternator. I am showing 17.9v in both places... Here is where it gets interesting. When I hit the brakes, the lights go off like nothing ever happened but once I hit the gas again and get the rpms up, the lgihts on the dahs come right back up. Well, it doesn't look like I am losing charge, but it is over charging the system.. I figured the voltage regulator is shot and I ordered a new alt from a local pep boys... Anyone else have some insight??

Tom
Greetings Tom,

The dash indicator lights test circuit, incorporates blocking diodes to eliminate a sneak circuit which would otherwise exist. In an event involving faults within the alternator rectifier network, alternating current is induced on line. The result is pulses of reverse voltage, which pass the blocking diodes in the test circuit and energise the indicator lights.

It could be that your voltmeter is reading spikes on the line, a scope would give you the answer.

A voltage regulator fault could also be the problem. One way or the other you are probably up for an alternator rebuild.

N.B. But on second thoughts you should check the second wire that goes to the alternator for an open circuit. This provides a direct sensing circuit from the battery to the voltage regulator, so that any voltage drop does not cause an error. (Those pushing the "upgrade?" should take note.)

Disconnected from the alternator, you should read battery voltage, 12 volts min. at the alt. end. You will appreciate that if this circuit is open, the charge voltage could go high.

Best of luck with it, Trevor.
__________________
Trevor, New Zealand.

As a child, on cold mornings I gladly stood in cowpats to warm my bare feet, but I detest bull$hit!
Reply With Quote
  #4  
Old 01-03-2007, 06:14 AM
Earthworm's Avatar
Earthworm Earthworm is offline
Meow!
 
Join Date: Mar 2002
Location: Winnipeg, Manitoba
Posts: 11,957
Send a message via ICQ to Earthworm Send a message via AIM to Earthworm Send a message via MSN to Earthworm Send a message via Yahoo to Earthworm Send a message via Skype™ to Earthworm
I had this issue as a result of a loose battery cable but it sounds, as Trevor said, like the wire(s) going to the alternator.
Reply With Quote
  #5  
Old 01-03-2007, 08:53 AM
dannmarr's Avatar
dannmarr dannmarr is offline
I work for my SVX
 
Join Date: Jan 2005
Location: Pocono Lake, PA
Posts: 1,647
Registered SVX
Keep in mind: When you check the wire going into the Alternator from the ignition, one side of the connector will have a voltage reading but the other side will not (until you turn the ignition key, then you will also have a voltage reading).

Last edited by dannmarr; 01-04-2007 at 04:12 PM.
Reply With Quote
  #6  
Old 01-03-2007, 10:00 AM
Ricochet's Avatar
Ricochet Ricochet is offline
I brought some ham.
 
Join Date: Jul 2005
Location: Columbus OH
Posts: 1,868
Send a message via AIM to Ricochet Send a message via MSN to Ricochet Send a message via Yahoo to Ricochet
Quote:
Originally Posted by Hocrest
All those cars, engines and parts sitting around and no extra Alts??????
don't give him ideas, my car's there right now!

__________________
Brian
Reply With Quote
  #7  
Old 01-03-2007, 01:30 PM
TomsSVX's Avatar
TomsSVX TomsSVX is offline
Maniac modifier
 
Join Date: Dec 2003
Location: Branchburg, New Jersey
Posts: 15,489
Registered SVX Classic SVX
Brian, it never crossed my mind... I have my silver to drive when the teally is down and out... I picked up a new alt today, and it has fixed the problem... I guess it was the regulator because I checked all of the connections and they were fine... Thanks guys, this is another case closed

Tom
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -6. The time now is 11:32 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
© 2001-2015 SVX World Network
(208)-906-1122