volt meter reading 18 volts ? - JeepForum.com
 
LinkBack Thread Tools
post #1 of 4 Old 01-17-2010, 09:06 AM Thread Starter
RangerOne
Registered User
1978 CJ7 
 
Join Date: Aug 2009
Location: Georgia
Posts: 14
volt meter reading 18 volts ?

I just installed a new autometer volt meter in my CJ. When I turn on the switch the meter is reading 18 volts. Im also having trouble with either the brain box or the coil burning up I dont know witch one it is. I tested the battery and its reading 12 volts. Any ideas

RangerOne is offline  
Sponsored Links
Advertisement
 
post #2 of 4 Old 01-17-2010, 01:16 PM
chainz
Registered User
1976 CJ5 
 
Join Date: Mar 2009
Posts: 239
Where is your voltmeter sensing voltage from? It should be at a source that is powered up by the ignition switch. If you are indeed getting 18 volts than that pretty much means your voltage regulator is full fielding the alternator which means overcharging the battery. What you do to check that is start the jeep and check voltage at the output of the alternator that charges the battery if it is 18 volts than you more than likely need a new regulator. And I would not drive the jeep if it were mine and putting out 18 volts your battery will be toast in no time which would also explain why your electronics are going out is too much volts.
chainz is offline  
post #3 of 4 Old 01-17-2010, 01:31 PM
Mike Romain
Registered User
1986 CJ7 
 
Join Date: Nov 2007
Location: Off the Grid in Chester Grant
Posts: 18,090
Bad meter is my first thought. It can't magically create 6 volts with just the switch on.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
Some Canadian Bush Jeep Runs and Build Photos: http://mikeromainjeeptrips.shutterfly.com (10 new albums added Sept 16/10)
Mike Romain is offline  
post #4 of 4 Old 01-17-2010, 02:43 PM
JeepHammer
Running On Empty...
1973 CJ5 
 
Join Date: Aug 2007
Location: South West Indiana
Posts: 11,175
Quote:
Originally Posted by RangerOne View Post
I just installed a new autometer volt meter in my CJ.

When I turn on the switch the meter is reading 18 volts.
When you mean you turn the ignition switch 'ON'...
Is that with the engine running, or NOT running?

If your volt meter jumps to 18 volts when the engine IS NOT running, but the switch is in the 'RUN' position,
Then you have a bad gauge.

If the volts are around 12 when the engine is 'Off' but the switch is in the 'RUN' position,
THEN it jumps up to around 18 volts when you start the engine,
That means the alternator is shot and the voltage regulator isn't doing it's job.

Quote:
Im also having trouble with either the brain box or the coil burning up I dont know witch one it is.
Which is it?

Either the coil is what needs replaced, the two aren't interchangeable,

And when you say 'Brain Box',
Do you mean the ignition module or the timing computer?

Usually the only way to kill a coil is to leave the ignition switch in the 'Run' position too long without engine running,
Or to NOT have sufficient 'Ground' to the engine heads.

Lack of 'Ground' to the module will make it act strange and eventually burn the module up.

Quote:
I tested the battery and its reading 12 volts. Any ideas
Start with taking a battery voltage reading after the vehicle sits a couple of days.
Make sure you note down EXACTLY what the voltage was,
Then start the engine, let it run 10 minutes or so,
Then take the voltage at the battery again.

If your battery voltage starts below 12.2 volts, you have a problem with the battery.

If the voltage gets above 14.7 volts, you have a problem with the alternator/voltage regulator.

With the engine turned 'Off',
Take a RESISTANCE reading between the alternator case and the battery negative terminal.
If you show any resistance more than an Ohm or two,
You need to install a dedicated ground wire between battery negative terminal and alternator case.

Start the engine, and do the same resistance test between alternator and negative battery terminal.
If your resistance goes up, then you need a larger, more direct connection between alternator case and battery terminal...
JeepHammer 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









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




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



Similar Threads
Thread Thread Starter Jeep Forums Replies Last Post
Why Would Volt Meter Flicker??? qwert98 Jeep CJ Forum 8 11-29-2013 10:23 AM
Volt Meter Jumping hieber22 Jeep CJ Forum 8 10-08-2009 08:00 AM
How Many volts should the Optima Red top reading? mowjoecj Jeep CJ Forum 11 12-31-2008 10:33 AM
Volt Meter issues? mmillen Jeep CJ Forum 31 12-13-2008 01:14 PM
74 oil and volt meter guage? my old cj Jeep CJ Forum 1 11-14-2008 09:06 PM

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