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Unread 09-19-2004, 08:49 PM   #1
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Join Date: Jun 2004
Posts: 57
YJ voltage gauge, battery drain

Does anyone know where along the line the voltage gauge takes it's reading from?
Before I replaced the alternator today, the gauge would alternate between 12v and 14v with the motor running, depending on what day it was. However, putting my voltmeter on the battery terminals always gave me a reading between 14v and 15v, like it should.
Now it's giving me a consistent reading of about 10v when I crank it up, then it climbs to just over 12v within a few seconds of cranking. If I put the voltmeter on the battery, I still get between 14v and 15v. 12v is where it stays though, it never gets above that like it did before I swapped alternators.
The reason I swapped alternators was because the old one was original and it was squealing pretty bad. Something has been draining my battery too. If I let it sit for more than 24 hours, there's not enough juice in it to crank the engine over. I've tested everything I could think of, and the only thing I can figure is that while the old alternator was charging, something in it was also causing the drain.
I guess we'll see.

Does anyone know of anything I can check to track down this battery drain? I put on new battery terminals, checked all grounds, and looked all over the place for wires that might have grounded out and have found nothing. Everything looks to be in good order.

littlejohn is offline   Reply With Quote Quick reply to this message
Unread 09-20-2004, 08:51 AM   #2
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1982 CJ8 
Join Date: Jun 2002
Location: Boston Area
Posts: 3,594

First, I am not a Jeep Electrician and really don't know much about Jeep and its electrical systems BUT...

Your problem sounds like a grounding or connector issue.

Have the alternator Load-Tested to see if it is holding up to the system load, clean the post on the battery, use some non-corrosive conducting paste to help keep things clean and the electricity flowing; use some on the ground connection too but not too much.

Then double check grounds, battery first. Make sure the “battery to block” is a good connection and the “engine to body strap” is still there and not corroded.
Under the Dash look for a ground strap for the gauges, maybe one maybe more, each gague may be grounded either w/ strap or through the meter itself to the dash panel, cehck for corrosion. Look to see where the feed for the volytagemeter comes from; I would think the wire comes from the ignition or fuse panel, but I've been wrong before.

An in-dash voltmeter only read system voltage not what is or isn’t coming out of the alternator, so if there is a problem this meter may only read what is making it to the meter.

Now, any Jeep mechanics around...

Sorry I can’t tell you exactly where the meter wiring taps into the main harness but get an electrical schematic for your vehicle and start tracing wires.


Do it right the first time !
Scrambler82 is offline   Reply With Quote Quick reply to this message

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