WK CRD Battery Light Challenge - JeepForum.com
LinkBack Thread Tools
post #1 of 3 Old 03-23-2015, 07:51 AM Thread Starter
Registered User
Join Date: Nov 2014
Location: Lunenburg
Posts: 2
WK CRD Battery Light Challenge

Hi, I've looked through the forum and pretty much every site I can find for an answer to this challenge, and still have not found a solution - figured I'd post here and see if anyone has a suggestion prior to my going to the dealer... I think I've checked all the obvious stuff, but I must be missing something.

Long story short, son changed oil, failed to put cap on right, fixed cap after massive oil leak, about 2K miles later, I turned on the heated seat, and the battery light comes on, and the heated seat shuts off. Do a quick search, known problem with the alternator. Double check and sure enough, no voltage coming out of the now oil soaked alternator, battery being drained while driving - OBDII meter reads 11.2 volts and dropping....

Purchase a new alternator and belt, and put it in (thanks to the forum for some hints on how to snake that thing out of there, was like rubiks cube figuring out how to get it out). Put the new alternator in, clean up the wires, re-connect everything, put the new belt on, good to go.

Start up the vehicle - battery light still on, AND heated seats still auto-shut off in 3 seconds, and rear window defroster won't come on. (I'm ASSUMING the computer senses low battery condition, and auto-shuts off high drain stuff like the seat heaters and rear defroster, but that is just an ASSUMPTION - I can't find anything documented on that). I check the battery, and voltage there is about 14.5 and charging - all seems good so figured it may be just that the battery was low. Goes for a few days and battery light is still on, and still no heated seats or glass defroster. Check battery again, and now it reads 13.2 volts when not running, and 14.5 or so when running, which seems right based on the ambient temp and all. Bring the battery down and have it checked - they tell me the battery is fine (it is only 1 year old). Another week, battery light still on, but not having any issues, i.e. drive day and night, never a voltage problem. OBDII meter (built into the car stereo) shows about 14.2 to 14.5 pretty steadily except for right after I start the vehicle. Just to play it safe thinking it may be the battery I buy a new battery. Clean all connections, put the new one in... SAME Problem, battery light on, no heated seats and no rear defroster! It has been over a month now, battery is at 13.3 or so volts when off, and charges between 14.2 and 14.8 depending on temp, so manual checking all looks good. No OBDII codes, no check engine, just the battery light.

Did the voltage drop test - 0.15V drop between alternator and battery with everything running, 0.02V drop between ground of battery and alternator case which seems to be within normal values based on other threads here I've read.

The ONLY thing I have noticed, is the OBDII voltage is about .5 volts lower than a meter on the battery - i.e. when OBDII says 14.2, a meter on the battery shows 14.7. Not sure why the OBDII reads a little different, but also don't know where OBDII is getting its data, or how it is calibrated. Given I've checked the grounds and connections, any thoughts on what else it could be? I did reseat the cable on the alternator (going into back) but no difference. Anyone know what causes the battery light to come on? Anyone know if the heated seats and rear defroster are indeed tied to the Batt light? Anyone have any thoughts on what it could be, i.e. how can the charging system seem to be working perfectly well, yet the battery light is still on.

Sorry this is so long, but wanted to provide as much detail as possible so people realize what I am experiencing, and what I've checked to date, and figured the devil may be in the details.


kckenkc is offline  
Sponsored Links
post #2 of 3 Old 03-26-2015, 12:03 PM
Registered User
2008 WK 
Join Date: Sep 2013
Location: Chula Vista
Posts: 134
Anything above 14.6vdc on a full batter is overcharging take the alternator out and have it checked and or replaced. The car is probably shutting down certain non vital equipment to protect them from an over voltage

willyok is offline  
post #3 of 3 Old 04-06-2015, 07:08 AM Thread Starter
Registered User
Join Date: Nov 2014
Location: Lunenburg
Posts: 2

Just wanted to close this out. It WAS indeed the new alternator that was bad (even though it had inspected and QC stickers on it lol).

For future reference, it turned out to be the feedback on the alternator (small connector). I now know the tell-tale sign is when the voltage on the battery is different than the voltage as indicated by the OBDII, chances are there is something wrong with this loop back. I had the alternator inspected, and they said the voltage looked good, and their "guess" was also the voltage coming out of the feedback/control side of the alternator. So, I took the hit, 3 hours and pulled / replaced it with another new one (covered under warranty so no cost with it, just time). As soon as I started it up, the battery light went out, and the heated seats and rear window defroster started working. Also checked the voltage and the battery voltage (when running) and the OBDII voltage are identical now.

So lessons learned:
- When OBDII voltage is different than battery voltage, it could be the feedback/control signal from the alternator.
- The heated seats and rear-window defroster are indeed disabled by the computer when the system is reporting the voltage is off (battery light on).
- Even though a component is brand new, it can be bad!
kckenkc is offline  

alternator , battery , defroster , heated seats

Quick Reply

Register Now

In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.

Email Address:


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page

Posting Rules  
You may post new threads
You may 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 On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome