Dead Battery or Broken Alternator? - Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > TJ Jeep Wrangler Forum > TJ Tech Forum

Join Wrangler Forum Today



Reply
 
Thread Tools

Please support our sponsors and let them know you heard about them on WranglerForum.com
Old 01-10-2017, 01:14 PM   #1
Newb
 
Trenthw's Avatar
 
Join Date: Nov 2014
Location: Southern California
Posts: 7
Trenthw is on a distinguished road
Dead Battery or Broken Alternator?

So yesterday and this morning my Jeep has been turning over very slowly. Like instead of the normal "Click click click start" it was more like "Buuuuur... Buuuuur....... Buuuuuuuur..... start". I drove to my school which is pretty far and when I pulled into the parking lot my dash and radio both flickered off and then on again. Now I'm sitting in class a little worried if my Jeep will even start. Do you guys think it could just be a bad battery? Because it seems like the battery is still dead after I drove all that ways I'm worried it could be the alternator.
Trenthw is offline   Quote
Old 01-10-2017, 01:19 PM   #2
Jeeper
 
Join Date: Aug 2016
Location: Albuquerque NM
Posts: 32
kbrown11 is on a distinguished road
You have a couple of options here, you can have it jump started and if it starts you will be able to get home. The battery and alternator can both be tested for free at most autopart stores.

kbrown11 is offline   Quote
Old 01-10-2017, 01:34 PM   #3
Moderator

WF Supporting Member
::WF Moderator::
 
Sinister6's Avatar
 
Join Date: Jan 2013
Location: Colorado Springs
Posts: 7,921
Sinister6 is on a distinguished road
Are the terminals clean? Test the battery and alternator.
__________________
The Wolf is not concerned with the opinion of sheep.

MY BUILD: :
http://www.wranglerforum.com/f322/si...ad-235526.html
Sinister6 is online now   Quote
 
Old 01-11-2017, 12:45 PM   #4
Jeeper
 
holy_crap's Avatar
 
Join Date: Feb 2013
Posts: 78
holy_crap is on a distinguished road
Jump start or push start (if you have a manual) the Jeep. Then with the engine running, disconnect the battery. If the engine shuts off, probably means the alternator is bad and not supplying enough juice for a spark. At least that is what I was told to do years back with my old VW Beatle.
holy_crap is offline   Quote
Old 01-11-2017, 01:15 PM   #5
Jeeper
 
CzerOne's Avatar
 
Join Date: Feb 2016
Location: Bedford, NS
Posts: 403
CzerOne is on a distinguished road
Whatever you do, do not disconnect the battery when the vehicle is running. You may end up damaging circuits in radio, computer modules, basically anything with a circuit board.
__________________
2003 TJ Sport
BDS|WARN|JKS|MOTIVE|COOPER|PROCOMP|BESTOP|TERAFLEX |SMITTYBILT|TOMWOODS|G2|RUGGEDRIDGE
CzerOne is offline   Quote
Old 01-11-2017, 05:39 PM   #6
Supporting Member

WF Supporting Member
 
jkjeeper06's Avatar
 
Join Date: Jul 2010
Posts: 3,973
jkjeeper06 is on a distinguished road
check grounds too
__________________
"You didn't buy it to look at it"
2000 TJ Solar yellow, 3.73, 178k, limited slip D44
2012 GMC sierra crew cab--Daily Driver
2008 jk X 6spd Red Rock---Sold and missed
jkjeeper06 is offline   Quote
Old 01-11-2017, 08:26 PM   #7
Jeeper
 
68charger's Avatar
 
Join Date: Oct 2016
Posts: 43
68charger is on a distinguished road
What is the voltage at the battery terminals when running?
68charger is offline   Quote
Old 01-11-2017, 08:38 PM   #8
Moderator

WF Supporting Member
::WF Moderator::
 
Sinister6's Avatar
 
Join Date: Jan 2013
Location: Colorado Springs
Posts: 7,921
Sinister6 is on a distinguished road
Quote:
Originally Posted by holy_crap View Post
Jump start or push start (if you have a manual) the Jeep. Then with the engine running, disconnect the battery. If the engine shuts off, probably means the alternator is bad and not supplying enough juice for a spark. At least that is what I was told to do years back with my old VW Beatle.


PLEASE DO NOT DO THIS!!!! Worst case scenarios include: battery blows up... You get acid in your eyes/skin, fry your PCM, blow other electronics, fire...

Test your battery and alternator with a multimeter. I like to test the battery after vehicle has sat overnight, test battery with vehicle off. Then start vehicle and test battery again, then put MM on alternator leads to see if it's giving you good voltage.
__________________
The Wolf is not concerned with the opinion of sheep.

MY BUILD: :
http://www.wranglerforum.com/f322/si...ad-235526.html
Sinister6 is online now   Quote
Old 01-12-2017, 07:23 AM   #9
Jeeper
 
Wattapunk's Avatar
 
Join Date: Mar 2012
Location: North TX
Posts: 2,896
Wattapunk is on a distinguished road
Start first by removing the terminals and scrubbing them sparkling clean and retightened. If you have a multitester/voltmeter, check battery voltage with engine off and then with engine idling. There should be about a 1.5v (+/-0.3) difference in the 2 readings. (around 12v versus 13.2-13.8v with alternator)

Or you can drive it to an auto parts store to have it load tested. If the battery is over 3 yrs old, it's highly likely you have a bad battery that's not holding charge from the alternator, which I see as more common on TJ's versus a failing alternator.

Wattapunk is offline   Quote
Reply

Thread Tools

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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




Download our Mobile App

» Featured Product

All times are GMT -5. The time now is 09:45 PM.


User Alert System provided by Advanced User Tagging v3.1.0 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.

Jeep®, Wrangler, Liberty, Wagoneer, Cherokee, and Grand Cherokee are copyrighted and trademarked to Chrysler Motors LLC.
Wranglerforum.com is not in any way associated with the Chrysler Motors LLC
« Back

Enter your email address:

Delivered by FeedBurner