Welcome to the North American Subaru Impreza Owners Club Friday January 17, 2020
Home Forums Images WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Go Back   NASIOC > NASIOC Technical > Service & Maintenance

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.







* As an Amazon Associate I earn from qualifying purchases. 
* Registered users of the site do not see these ads. 
Reply
 
Thread Tools Display Modes
Old 12-08-2019, 02:27 PM   #1
challeen42
Scooby Newbie
 
Member#: 472151
Join Date: Aug 2017
Default 2005 Subaru STi Brake, Rear Diff Temp, and Battery Lights all come on in Unison

I have has this car for 3 years now and have went through atleast 5 alternators. When the lights first registered, I replaced the alternator with some duralast reman that kept the lights off for around two weeks. I went back to get a better version of the duralast and the same result. I got a brand new $400 alternator from duralast and still got the same result. My car has been eating through these alternators. Finally I decided to get the OEM Denso 210-4227 alternator. The worst part about all of this is that when Autozone or NAPA would check the alternators, they would come up working just fine every time on their machine. I found one brand new and it worked for probably 10 months. Then I searched for another alternator, but I couldn't find anybody that sold brand new ones so I got an old reman Denso thinking it should work just fine, but it only lasted a month.

The thing about this is it seems like the voltage of my alternator isn't bad. It bounces between 12.5 to 14.8 while i am driving the car in town. It doesn't ever try to die or anything either. The only thing that happens is the battery, brake, and rear diff temp lights all come on and off in sync with each other. They never come on one by one or without each other. I also noticed that my alternators have always ran hot, but I read that that isn't that big of a deal.

My battery was relocated to the trunk of the car before I bought it and it has always had this problem. The battery to started wire is 2 gauge srg copper wire. Then there is another wire running to the positive post of the battery that is either 6 or 8 gauge, but I lose it when it goes through my firewall.

Sorry for this being so long, but this is the most stubborn annoying fight that I have had with this car and I need to figure it out. Please let me know if you guys have nay ideas and let me know if you need any more information.
* Registered users of the site do not see these ads.
challeen42 is offline   Reply With Quote
Sponsored Links
* Registered users of the site do not see these ads.
Old 12-08-2019, 07:55 PM   #2
Big-E
NASIOC Supporter
 
Member#: 123843
Join Date: Aug 2006
Chapter/Region: NESIC
Location: Connecticut
Vehicle:
2016 STI LTD CWP
Let LED's light your way!

Default

My suggestion is to make sure that all of the OEM ground points are clean: there are two on the intake manifold and one from the block to the frame.

Then I would add additional grounds from the engine accessory brackets, to the intake manifold, then to the frame. Also make sure that the transmission is properly grounded to the engine/frame.

At the rear you need to make sure that the battery is also properly grounded to the frame and perhaps at multiple points: one main 2/0 gauge wire and then one or two smaller 8-gauge wires.
Big-E is offline   Reply With Quote
Old 12-08-2019, 09:06 PM   #3
WolfPk
Scooby Newbie
 
Member#: 498388
Join Date: Feb 2019
Vehicle:
2007 STI
Obsidian Black Pearl

Default

yeah def sounds like grounding issue, check all terminals and also ground points as mentioned above.
WolfPk is offline   Reply With Quote
Old 12-08-2019, 09:46 PM   #4
turboblew
Scooby Newbie
 
Member#: 508225
Join Date: Nov 2019
Chapter/Region: South East
Location: North FL
Vehicle:
2006 Subaru
Fusia

Default

I hadnt replaced that many alternators in my life... aint no way Im trusting those mopes at the store to do anything except refund my money.
turboblew is offline   Reply With Quote
Old 12-09-2019, 12:29 PM   #5
challeen42
Scooby Newbie
 
Member#: 472151
Join Date: Aug 2017
Default

Do you know where the engine block to chassis ground is? If that were a problem wouldn't I have way more problems too? The intake grounds are tight for sure. Also it seems like the lights only come on when the motor is under load when I am speeding up. When I am slowing down the lights slowly go away.
challeen42 is offline   Reply With Quote
Old 12-09-2019, 06:29 PM   #6
challeen42
Scooby Newbie
 
Member#: 472151
Join Date: Aug 2017
Default

Do you know where the engine block to chassis ground is? If that were a problem wouldn't I have way more problems too? The intake grounds are tight for sure. Also it seems like the lights only come on when the motor is under load when I am speeding up. When I am slowing down the lights slowly go away.
challeen42 is offline   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 -4. The time now is 05:47 PM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2020 Axivo Inc.
Copyright ©1999 - 2019, North American Subaru Impreza Owners Club, Inc.

As an Amazon Associate I earn from qualifying purchases.