Charging system puzzle -- '99 XJ - JeepForum.com
 5Likes
  • 1 Post By CJ7-Tim
  • 1 Post By chris87xj
  • 1 Post By S8NNG8
  • 1 Post By billb2011
  • 1 Post By Ralph77
 
LinkBack Thread Tools
post #1 of 13 Old 07-14-2019, 11:15 PM Thread Starter
Davy A
Registered User
 
Join Date: Jul 2019
Posts: 4
Xj Charging system puzzle -- '99 XJ

While driving recently, the "Check Gauges" light on the dashboard came on, and I noticed that the alternator gauge was all the way down, reading 9. When I got home, put a digital voltmeter on the battery terminals, and the reading was only about 11.7 volts (with the engine running), so I figured the alternator had failed. I didn't have time to deal with it, so I parked it, and started using a different vehicle.

I finally got around to checking it out, and after starting the engine, was surprised to see that the alternator gauge was now reading nearly 14 volts. I drove about 5 miles to town, and the gauge stayed at that mark the whole time. I shut it off, went into the store, and when I came back out and restarted it, the "Check Gauges" light came on, and the gauge showed about 9 volts again. I drove home, and the gauge stayed at 9. I again checked the voltage at the battery with the engine running, and got a reading of about 11.7 volts, so it didn't appear that the alternator was charging.

A couple of hours later, I again started the engine, and was surprised to see the alt gauge now reading just a hair below 14. Keeping the engine running, a took another voltage reading at the battery terminals, and got a reading of about 13.8 volts, so apparently the alternator was then charging.

This intermittent business has me baffled. If the problem were a bad alternator, wouldn't it just never charge?

Any input welcome!

Davy A is offline  
Sponsored Links
Advertisement
 
post #2 of 13 Old 07-15-2019, 08:51 PM
chris87xj
JF Admin
 
chris87xj's Avatar
1987 XJ Cherokee 
 
Join Date: Sep 2006
Location: 3rd rock from sun
Posts: 13,863
A dirty intermittent connection at the alternator or either end of a battery cable can cause symptoms like this.

***Chris***

"You can set my jeep on fire and roll it down a hill,
But I still wouldn't trade it for a Coupe DeVille."


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

chris87xj is online now  
post #3 of 13 Old 07-16-2019, 04:55 AM
CJ7-Tim
Real Jeeps have dents
 
CJ7-Tim's Avatar
2000 XJ Cherokee 
 
Join Date: Apr 2002
Location: out in the garage - Minneapolis
Posts: 27,411
When the alternator brushes wear out, they can become stuck and the alternator will stop charging. Typical symptoms would be as you noticed, 9 volts indicated on the gauge, and charging that returns to normal when you hit a bump, or stop and restart the engine. As suggested already, cleaning and checking the alternator wire connections is free and easy.

New brushes are probably all that is needed. If you buy a "rebuilt" alternator have it tested before you leave the auto parts store. 5 - 10 % of Chinese "rebuilt" alternators are rebuilt incorrectly and either are faulty before you leave the parts store, or will fail quickly.
chris87xj likes this.

.

A recent Gallup public opinion poll shows the NRA, at 58% approval, has a higher approval rating than either Hillary Clinton or Barack Obama.

Progressive Liberalism: Bringing you new Healthcare ideas so wonderful, they have to include mandatory participation ...

Originally Posted by Ronald W. Reagan: Government is not the solution to our problems; Government is the problem.
CJ7-Tim is offline  
 
post #4 of 13 Old 07-16-2019, 07:37 PM Thread Starter
Davy A
Registered User
 
Join Date: Jul 2019
Posts: 4
Davy A

Thanks for the posts, guys. You know, now that I think about it, this issue began not long after I replaced the spark plugs.

The plugs hadn't been changed in a while, and it was a bit of a battle even getting the boots of the spark plug wires off of the plugs (finally had to use one of those tools that looks like a pair of needle nosed pliers with a loop to get them loose). It's possible that I pulled something loose during that project. I will definitely check the connections.

If the problem is due to worn brushes, are replacement brushes readily available? I wouldn't mind trying to tackle replacing them.

Again, thanks!
Davy A is offline  
post #5 of 13 Old 07-17-2019, 07:41 AM
2oldjeeps
Registered User
2000 XJ Cherokee 
 
Join Date: Aug 2017
Posts: 1,146
when i had funny charging it was the belt. snug up, its fine.
there is no way i can tell if/when i get it right.
always feels too tight...

99wj,143,000 miles
00xj,177,000 miles
10hummer3,74,000 miles
98xj,130,000 miles
2oldjeeps is offline  
post #6 of 13 Old 07-19-2019, 12:06 AM Thread Starter
Davy A
Registered User
 
Join Date: Jul 2019
Posts: 4
Hmmm...hadn’t thought about belt tension, but another thing to check out. Occasionally, during rainy weather, the belt seems to be a bit noisy, having a “chirp,” maybe caused by being a bit loose? I agree, hard to tell the proper tension...had a better feel for proper tension on the individual v-belts that drove alternators, power steering pump, etc. Thanks for the additional suggestion.
Davy A is offline  
post #7 of 13 Old 07-19-2019, 03:21 AM
chris87xj
JF Admin
 
chris87xj's Avatar
1987 XJ Cherokee 
 
Join Date: Sep 2006
Location: 3rd rock from sun
Posts: 13,863
XJs do like a tight belt, tighter than most.
Davy A likes this.

***Chris***

"You can set my jeep on fire and roll it down a hill,
But I still wouldn't trade it for a Coupe DeVille."


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

chris87xj is online now  
post #8 of 13 Old 07-19-2019, 07:02 AM
S8NNG8
Registered User
 
S8NNG8's Avatar
1995 XJ Cherokee 
 
Join Date: Feb 2012
Location: Helena
Posts: 10,224
My ZJ was having the same exact problem. Tightening the belt fixed it. Take note in your examples that your problem seems to be arising after the engine/belt are warmed up/stretched.
Davy A likes this.

D3<!L!>3D
S8NNG8 is online now  
post #9 of 13 Old 07-21-2019, 09:05 AM
billb2011
Registered User
1999 XJ Cherokee 
 
Join Date: Jul 2011
Location: Minford
Posts: 181
Have you been mudding recently. About every other trip I take into the woods I usually pull the alternator off and take it apart and clean the brushes on it and put a little oil on them. Sandy mud can make the brushes stick and cause the alternator to intermittently work/not work. Clean everything inside it with contact cleaner.
Davy A likes this.

"If you lend somebody $20 and you never see that person again, you might consider that money well spent." ~unknown
billb2011 is offline  
post #10 of 13 Old 07-21-2019, 09:57 PM Thread Starter
Davy A
Registered User
 
Join Date: Jul 2019
Posts: 4
Red face Davy A

Thanks again for the suggestions. I will definitely start by checking the belt tension, and take it from there. Will let you know what happens.
Davy A is offline  
post #11 of 13 Old 07-22-2019, 06:31 AM
Ralph77
Registered User
2000 XJ Cherokee 
 
Join Date: Aug 2015
Posts: 1,884
Quote:
Originally Posted by Davy A View Post
Thanks again for the suggestions. I will definitely start by checking the belt tension, and take it from there. Will let you know what happens.
Thing about the belt tension is that using the "yeah that looks about right" method has been far off in my experience.
I broke down and bought this:

https://www.amazon.com/Gates-91132-B.../dp/B000CRDLZM
Davy A likes this.
Ralph77 is online now  
post #12 of 13 Old 08-02-2019, 09:55 AM
2oldjeeps
Registered User
2000 XJ Cherokee 
 
Join Date: Aug 2017
Posts: 1,146
my problem is back. dont feel like pulling the alt. lazy...
it goes half way,pause, drop down...

99wj,143,000 miles
00xj,177,000 miles
10hummer3,74,000 miles
98xj,130,000 miles
2oldjeeps is offline  
post #13 of 13 Old 08-08-2019, 12:05 AM
BagusJeep
Web Wheeler
 
BagusJeep's Avatar
1981 CJ7 
 
Join Date: Jul 2009
Location: Bali
Posts: 6,818
you may have a Nippon Denso alternator, you can get the brushes and holders on Amazon for about $9. I understand (not done it myself, a mechanic fixed it for $10 last time it dropped output) that this model is very simple for brush replacement.

It may of course also be loose connections.

BagusJeep lives in Bali.

1981 CJ7 258ci - Bagusjeep
1984 CJ7 258ci - Puthijeep
1981 J20 258ci - Gladys
1951 Willys CJ3A/MB/M38 - Little Willy
1995 Cherokee 4.0 - CHEROKEE
BagusJeep is offline  
Reply

Quick Reply
Message:
Options

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

Password:


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



Email Address:
OR

Log-in











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