Battery light still on after new battery/alternator? - Focus Fanatics
Ford Focus Forum
HomeContact UsAbout UsGalleryDiscussion ForumsMarketplace


Go Back   Focus Fanatics > Ford Focus Tech Discussions > General Technical Chat

General Technical Chat This section is for technical discussions relating to general maintenance, electrical issues, engine trouble, and recalls.

Search This Forum | Image Search | Advanced Search    
Ford Focus Tire & Wheels FocusFanatics Merchandise

Reply
 
Thread Tools Display Modes
Old 06-22-2011, 10:12 PM   #1
BurnsRubber
Focus Enthusiast
 
BurnsRubber's Avatar
 
Join Date: Jul 2008
Fan#: 57974
Location: SF Bay Area
What I Drive: '02 Sonic Blue SVTF

Posts: 73
FF Reputation: 1 BurnsRubber Good Standing Member
Buy-Sell-Trade Rating: (0)
Battery light still on after new battery/alternator?

Monday on my way home from work in the 100deg heat (first of the year) and the AC on full blast (obviously) the red battery light on the dash lights up. My first thought was alternator is going bad. I replaced the battery, just to elimunate it, also figuring it would be good PM anyway since it was 6 years old. On way into work the following morning, no light. OK. On my way home (103deg heat) the light comes on.

So today I take a day off work to replace the alternator. The handheld diagnostic at the part store said (low charging voltage). So I buy a new alternator from Napa. Rebuilt units have died on me. Alternator goes in (what a PITA!) I was expecting the light to go away. First drive out, AC full blast, it goes on. What gives?

I've read through many forum post on this. Seems there are a few other things to trouble shoot: cables, connectors, fuseable link (where is that?) I looked at the alternator wiring and connectors while replacing the alternator, no obvious problems. Battery terminals are clean. So what should I look at next? No symptoms with the car other than this idiot light.


__________________
2002 Sonic Blue SVTF w/EAP Wheels
Tom's tune
Centric Rotors (120.61071 & 120.61074) & Hawk HPS Pads
CFM STS, disabled clutch pedal sensor, removed shift linkage counter weight
BF Goodrich g-Force Super Sport A/S 225/45
BurnsRubber is offline  
    Reply With Quote
Sponsored Links
Advertisement
 
Old 06-23-2011, 12:01 AM   #2
viney266
Focus Fanatic
 
viney266's Avatar
 
Join Date: Jun 2003
Fan#: 93
Location: westminster, maryland, MD
What I Drive: focus ztw ,zx3,mustang, motorcycles

Posts: 25,573
FF Reputation: 112 viney266 Excellent Standing Memberviney266 Excellent Standing Member
Buy-Sell-Trade Rating: (4)
Did you put a new belt on?..I would replace the belt if you haven't
__________________
Speed is only a matter of money; how fast do you want to go?
viney266 is offline  
    Reply With Quote
Old 06-23-2011, 12:05 AM   #3
jetrinka
Focus Fanatic
 
jetrinka's Avatar
 
Join Date: Mar 2007
Fan#: 45622
Location: Snohomish, WA
What I Drive: 88 5-speed XR4TI

Posts: 7,528
FF Reputation: 180 jetrinka Excellent Standing Memberjetrinka Excellent Standing Member
Buy-Sell-Trade Rating: (6)
Do you have a way to measure the charging voltage at the battery? If so, measure the voltage at the battery while running and then measure from the positive lead on the alternator to battery ground. These two numbers should be very close to each other.

Most of the time a battery light indicates a problem with the internal regulator on the alternator itself. Check the main charging fuse as well.
jetrinka is offline  
    Reply With Quote
Old 06-23-2011, 12:06 AM   #4
Svt5.0
Focus Enthusiast
 
Join Date: Sep 2010
Fan#: 78677
Location: Antioch, CA
What I Drive: 03 Svt Focus

Posts: 147
FF Reputation: 1 Svt5.0 Good Standing Member
Buy-Sell-Trade Rating: (1)
whats the voltage output of the new alt you just put in? I have seen many bad units out of the box
__________________
...
Svt5.0 is offline  
    Reply With Quote
Old 06-23-2011, 12:20 AM   #5
mikebontoft
Toxx
 
mikebontoft's Avatar
 
Join Date: Aug 2008
Fan#: 58647
Location: SLC, UT
What I Drive: 5.9L Grand Cherokee ZJ

Posts: 25,861
FF Reputation: 76 mikebontoft Excellent Standing Member
Buy-Sell-Trade Rating: (3)
isnt there some common pigtail issue or something? sorry I don't know more about that but I remember something like that.
__________________
SR #127 | '02 Focus SE "Foci" (5.0 RWD - parting) | '90 Mazda 626 GT "Greenie" (2.2L turbo T3/T4 rebuild-sold) | '75 BMW 2002 "Carby" (resto-mod racecar) | '75 BMW 2002 (donor -sold) | '98 Jeep Grand Cherokee 5.9L (lifted and fast) | '99 BMW 328is (alt. daily).
Moderating General Chat Lounge, General Technical Chat, Ford Focus & General Car Chat, and Rocky Mountain Fanatics
mikebontoft is online now  
    Reply With Quote
Old 06-23-2011, 12:22 AM   #6
jetrinka
Focus Fanatic
 
jetrinka's Avatar
 
Join Date: Mar 2007
Fan#: 45622
Location: Snohomish, WA
What I Drive: 88 5-speed XR4TI

Posts: 7,528
FF Reputation: 180 jetrinka Excellent Standing Memberjetrinka Excellent Standing Member
Buy-Sell-Trade Rating: (6)
Supposedly the pigtail right off the alternator lead sometimes fries.
jetrinka is offline  
    Reply With Quote
Old 06-23-2011, 12:23 AM   #7
mikebontoft
Toxx
 
mikebontoft's Avatar
 
Join Date: Aug 2008
Fan#: 58647
Location: SLC, UT
What I Drive: 5.9L Grand Cherokee ZJ

Posts: 25,861
FF Reputation: 76 mikebontoft Excellent Standing Member
Buy-Sell-Trade Rating: (3)
ok yeah that's what I was thinking of
__________________
SR #127 | '02 Focus SE "Foci" (5.0 RWD - parting) | '90 Mazda 626 GT "Greenie" (2.2L turbo T3/T4 rebuild-sold) | '75 BMW 2002 "Carby" (resto-mod racecar) | '75 BMW 2002 (donor -sold) | '98 Jeep Grand Cherokee 5.9L (lifted and fast) | '99 BMW 328is (alt. daily).
Moderating General Chat Lounge, General Technical Chat, Ford Focus & General Car Chat, and Rocky Mountain Fanatics
mikebontoft is online now  
    Reply With Quote
Old 06-23-2011, 01:27 AM   #8
sparky34kv
Focus Enthusiast
 
Join Date: Mar 2009
Fan#: 63383
Location: Pen Argyl, PA, PA
What I Drive: 2004 Blue ZTW Wagon, 2.3 L Duratec

Posts: 141
FF Reputation: 1 sparky34kv Good Standing Member
Buy-Sell-Trade Rating: (0)
Had you charged the battery before running the car with the new alternator? If not, you may have had too much load on it with running the engine and charging the battery, which burns out the regulator in the alternator.
sparky34kv is offline  
    Reply With Quote
Old 06-23-2011, 06:07 AM   #9
whynotthinkwhynot
Captain TMI
 
whynotthinkwhynot's Avatar
 
Join Date: Jan 2005
Fan#: 18416
Location: the armpit of TN, Memphis, TN
What I Drive: 05 ZXW; 02 Windstar; 13 C-Max SEL

Posts: 20,085
FF Reputation: 270 whynotthinkwhynot Outstanding Standing Memberwhynotthinkwhynot Outstanding Standing Memberwhynotthinkwhynot Outstanding Standing Member
Buy-Sell-Trade Rating: (1)
Use the electronic odometer trick to see if the PCM is picking up voltage. Follow the directions in the How-To archive, and look for the display to read [bat 12.1]. If you see [bat 0] that might explain some things.

Physical inspection of the plug-in connector is the best way though, and most likely where the problem is.
__________________
Be eclectic.
---The Complete How-To Archive--

Moderating everything now, let me know if I can help.

Quote:
Originally Posted by the user formerly known as ZX3_Chick View Post
You're special aren't you.
whynotthinkwhynot is offline  
    Reply With Quote
Old 06-23-2011, 09:19 AM   #10
BurnsRubber
Focus Enthusiast
 
BurnsRubber's Avatar
 
Join Date: Jul 2008
Fan#: 57974
Location: SF Bay Area
What I Drive: '02 Sonic Blue SVTF

Posts: 73
FF Reputation: 1 BurnsRubber Good Standing Member
Buy-Sell-Trade Rating: (0)
How do I display voltage on the odometer? I found this: http://www.focushacks.com/?modid=37&...gnostic%20Mode

But could not get it to display a voltage.

Belt looked OK. It could be slipping with the AC on? Should have replaced it. Will look at connectors cables. How do I check generator voltage?

Got to drive it to work right now. Hope I don't get stranded...
__________________
2002 Sonic Blue SVTF w/EAP Wheels
Tom's tune
Centric Rotors (120.61071 & 120.61074) & Hawk HPS Pads
CFM STS, disabled clutch pedal sensor, removed shift linkage counter weight
BF Goodrich g-Force Super Sport A/S 225/45
BurnsRubber is offline  
    Reply With Quote
Reply

Bookmarks & Social Networks

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 -5. The time now is 09:47 AM.


Copyright 2002-2014 FocusFanatics.com. All Rights Reserved : Terms of Use : Privacy Policy : Advertise Information : Site Map

Focus Fanatics Ford Focus Forum offers many fun ways for you to engage with other Ford Focus Owners from across the world. Whether it be about the aftermarket performance modifications, technical how-to's, European tuned suspension or awesome fuel economy similar to the Acura TLX or Fiesta ST. You can find all Ford Focus and Focus ST related information here. Join our Ford Focus discussion forums and chat with local Focus enthusiasts in your area.