Welcome to the North American Subaru Impreza Owners Club Monday November 20, 2017
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
Go Back   NASIOC > NASIOC Technical > Electrical & Lighting

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.
* Registered users of the site do not see these ads. 
Thread Tools Display Modes
Old 09-29-2012, 02:03 AM   #1
Scooby Newbie
Member#: 14893
Join Date: Feb 2002
Location: El Paso, TX
2002 Impreza WRX

Default Alternator and ECU

Does the ECU control alternator output voltage? I have replaced the alternator on a 2002 WRX twice, and after a couple of hours voltage jumps all over the place again and eventually the alternator drops off line and fails.

Suggestions appreciated

Steve P
El Paso
* Registered users of the site do not see these ads.
P8S-WRX is offline   Reply With Quote
Sponsored Links
* Registered users of the site do not see these ads.
Old 09-29-2012, 12:30 PM   #2
Scooby Guru
Member#: 53443
Join Date: Jan 2004
Location: Anchorage, AK
2001 LL Bean Outback


I think it depends on what model you have. In the later years the ECU was involved with the circuit. Make sure the battery warning light works ok when you turn the key to the Run position. Current flows through it for the exciter circuit. Systems that involve the ECU should have 3 wires going to the back side of the alternator. Others use only 2 wires.
Cougar4 is offline   Reply With Quote
Old 09-29-2012, 01:41 PM   #3
Trust no one
Member#: 11170
Join Date: Oct 2001
Chapter/Region: Tri-State
Location: NYC
02 WRX
15 WRX/05 GTO


The '02 is internally regulated in the alternator, no ECU involvement. Make sure the battery is good, check all wiring especially main grounds.
Mulder is offline   Reply With Quote

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 07:16 PM.

Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2017 Axivo Inc.
Copyright ©1999 - 2017, North American Subaru Impreza Owners Club, Inc.