Battery gauge dropping to 9V - but strange behavior - Jeep Cherokee Forum

Notices
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here XJ (84-01)
All OEM related XJ specific tech. Examples, no start, general maintenance or anything that's stock.
Sponsored by:
Sponsored by:

Battery gauge dropping to 9V - but strange behavior

Old 02-12-2019, 10:43 AM
  #1  
Junior Member
Thread Starter
 
Join Date: Jul 2008
Posts: 36
Year: 1998
Model: Cherokee
Engine: 4.0 L 6 cylinders
Default Battery gauge dropping to 9V - but strange behavior

So yesterday I used my '98 XJ to go to work and after a little that I was driving, the battery gauge dropped to 9V (only battery gauge dropped, all others were working fine). But the car was driving fine. However, a few miles after the car died (no more electric power). Before it died I could feel it was "caughing" every time I pushed on the gas pedal. I used jumper cables with another car and the car started right away. I used a multimeter and I could measure 13.5V while the car was running. I then changed the battery and all was good. 14V voltage supply and car running great.

Until this morning, I started the car (with the new battery) and after a little bit, the battery gauge dropped again to 12V and then all the way down to 9V. I still had my multimeter in the car, pulled over and measured the voltage and it was 14V (while the gauge was stuck at 9V). Turned the car off and on again and then the gauge went back to 14V.

Can those be signs of a dying alternator? Or you think there is something else I should look for?

PS: weather here is cold (32F) and humid. Not sure if that could have an influence.

Thanks

Last edited by qwain76; 02-12-2019 at 10:55 AM.
qwain76 is offline  
Old 02-12-2019, 10:57 AM
  #2  
CF Veteran
 
Join Date: Nov 2017
Location: Groton, MA
Posts: 2,524
Year: 1995
Model: Cherokee(XJ)
Engine: I6 4.0L
Default

Before you do ANYTHING else, make sure your connections, grounds, battery cables are all clean and tight. You don't want to be chasing gremlins and firing the parts cannon over something as simple as a loose connection.

If your gauge reads 9 and the ACTUAL voltage is 14, then it's more than likely an issue with the gauge or it's wiring.
PatHenry is offline  
Old 02-12-2019, 01:06 PM
  #3  
Seasoned Member
 
Nick-B's Avatar
 
Join Date: Jun 2011
Location: Key Peninsula, WA
Posts: 308
Year: 1997
Model: Grand Cherokee
Engine: 4.0
Default

It sounds like you've had 2 issues. First a failing battery which you remedied. Second, there is the gauge or rather the electrical connections leading to it. This is a common problem and your volt gauge is not to be trusted. You'll never have a fully accurate reading since the power wire to the gauge is not a direct line to the battery or alternator, rather it makes several stops along the way and there are small losses incurred although not as drastic as only showing 9 volts.

First, thoroughly clean the battery cables and connection points at BOTH ends. I had the same problem on my old '90 XJ and after cleaning all the connections I could, I finally pulled the instument cluster and removed all the little lights and the gauges to where I just had the printed circuit sheet in my hands and then took a pencil eraser and carefully rubbed all the contact points clean and shiny. I say carefully as the printed circuit sheet is a bit delicate and you don't want to fold over or crease any areas as it could actually crack the copper traces. After I did this I no longer saw these large and false voltage drops at the gauge. Even the gauge lighting improved with all the contact points cleaned up.

Best of luck!

Last edited by Nick-B; 02-12-2019 at 01:09 PM.
Nick-B is offline  
Old 02-12-2019, 05:29 PM
  #4  
CF Veteran
 
Morat's Avatar
 
Join Date: Jan 2010
Location: North Riding of Yorkshire, UK
Posts: 1,119
Year: 1997
Model: Cherokee
Engine: 4.0
Default

Subbed - I have experienced the same issues. Havn't investigated further yet, XJ needs some other bits done.
Morat is offline  
Old 02-12-2019, 06:10 PM
  #5  
Member
 
Join Date: Dec 2018
Location: NJ
Posts: 105
Year: 1994/ 96 engine
Model: Cherokee (XJ)
Engine: 4.0 HO Straight 6 Baby!
Default

Well this is interesting..not hijacking but I was driving to work today and I noticed if I put my heat on high/fan...the batt gauge drops down to like 9 volts! If I turn the fan down to low it goes back up to 14. Same thing with the rear defrost button. I was like hmm maybe I will just turn that off. But as soon as I do the voltage goes right back up. The truck doesn't seem to be affected, all my lights are on relays...headlights and fogs...so they dont mess with the gauge. Just fan speed and rear defrost. I have a new battery and every time I test my Alternator it is solid..and I have covered every ground. I am curious to see what others have to say about this. Oh front and rear wipers also have no effect. hmmmmmmm
DCWinterXJ is offline  
Old 02-14-2019, 02:29 AM
  #6  
Junior Member
Thread Starter
 
Join Date: Jul 2008
Posts: 36
Year: 1998
Model: Cherokee
Engine: 4.0 L 6 cylinders
Default

Folks, thanks for the answers.
I cleaned the grounds under the hood and no difference, still 12V reading confirmed by multimeter.
Then I cleaned the contacts on the alternator and it came back to life, 14V!

However, tonight it dropped again to 12V. I restarted the car and went up to 14 again. it did it twice.

Is this a common faiure mode for alternators?

Or the issue might be somewhere else?
qwain76 is offline  
Old 02-14-2019, 12:25 PM
  #7  
Junior Member
 
Join Date: Nov 2016
Location: Lakewood, WA
Posts: 38
Year: 1999
Model: Cherokee
Engine: 4.0
Default

I would check the two connections under the little cover at the front of the PDC. One comes straight from the battery while the other comes from the alternator through an in-line fuse. I would check voltage coming out of the alternator and then at the PDC terminals. I'd also check the drive belt is nice and tight to ensure it is not slipping on the alternator pulley. That's a problem I had a while back in wet weather with no belt squealing to give it away.
tiger02 is online now  
Old 02-14-2019, 05:24 PM
  #8  
Junior Member
Thread Starter
 
Join Date: Jul 2008
Posts: 36
Year: 1998
Model: Cherokee
Engine: 4.0 L 6 cylinders
Default

Thanks. can you explain what you mean by PDC? which connectors do u refer to?

thanks
qwain76 is offline  
Old 02-14-2019, 06:39 PM
  #9  
CF Veteran
 
Join Date: Nov 2017
Location: Groton, MA
Posts: 2,524
Year: 1995
Model: Cherokee(XJ)
Engine: I6 4.0L
Default

PDC - Power Distribution Center - it's the box near the battery where the relays and big fuses are.
PatHenry is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
DeadmeatXJ
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
0
06-11-2017 09:25 PM
xj yj
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
4
11-21-2011 07:56 PM
pwb
Stock Grand Cherokee Tech. All ZJ/WJ/WK Non-modified/stock questions go here!
16
09-27-2011 08:22 AM
96ckeecntry
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
7
03-18-2011 09:13 AM
NewXJaddict
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
1
07-28-2010 10:33 PM

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 

Thread Tools
Search this Thread
Quick Reply: Battery gauge dropping to 9V - but strange behavior


Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description: