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Unread 06-14-2014, 07:33 PM   #1
pariah24
Registered User
2004 TJ Wrangler 
 
Join Date: Dec 2007
Location: Colorado Springs, CO
Posts: 157
Over-voltage in heat?

So yesterday it hit 95-96o here in Colorado, and as I was pulling in to a parking lot my AC blower speed suddenly increased and the volt gauge jumped up to 15, and the "Check Gauges" indicator lit up. I shut the engine down and tried restarting it, thinking maybe it was a one-off glitch but the voltage issue remained. I didn't have a voltmeter with me so I let the engine cool off a bit...and that seems to have done the trick. I made the drive home without any other indicators lighting up, and the volt gauge hasn't risen much above 14 yesterday or today.

Anyone had something like this happen before? I checked the battery connections, ground, fuses, etc. Nothing seems to be amiss but I'd rather try to catch it now instead of sitting on the side of the Interstate.

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Unread 06-14-2014, 09:16 PM   #2
wwch99tj
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1999 TJ Wrangler 
 
Join Date: Apr 2010
Location: Felton, Delaware
Posts: 2,940
Alternator is going bad, had the same problem a few years ago

Sent from my Galaxy Note 2 using my thumb
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Unread 06-14-2014, 10:20 PM   #3
Justins_TJ
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1997 TJ Wrangler 
 
Join Date: May 2010
Location: Adamsville, Tennessee
Posts: 67
Check your diagnostic codes. Mine was jumping up past 19 and I was getting a check engine light. I got a 46 code, Charging voltage to high. So I swapped the alternator. Got a 160 amp. Still did the same thing. And this all started when the temp got warm here too. Then I was thinking PCM because it controls the charging via the field circuit. So I got out my multimeter and my alternator was putting out a nice 14 volts at idle. Checked the voltage at the power distribution box, 14 volts. Checked the battery post, 12 volts. What the heck right. The wire going into the post connector had 14 but the post itself was only 12. There was corrosion where the wire went into the terminal block on the battery. That tiny bit of corrosion was dropping 2 volts right at the terminal post. Cleaned that out and no problems since. So make it easy on yourself and clean your post connectors first. On the plus side I finally had an excuse to get that 160 amp alternator.....
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Unread 06-15-2014, 09:30 AM   #4
pariah24
Registered User
2004 TJ Wrangler 
 
Join Date: Dec 2007
Location: Colorado Springs, CO
Posts: 157
Quote:
Originally Posted by Justins_TJ View Post
Check your diagnostic codes. Mine was jumping up past 19 and I was getting a check engine light. I got a 46 code, Charging voltage to high. So I swapped the alternator. Got a 160 amp. Still did the same thing. And this all started when the temp got warm here too. Then I was thinking PCM because it controls the charging via the field circuit. So I got out my multimeter and my alternator was putting out a nice 14 volts at idle. Checked the voltage at the power distribution box, 14 volts. Checked the battery post, 12 volts. What the heck right. The wire going into the post connector had 14 but the post itself was only 12. There was corrosion where the wire went into the terminal block on the battery. That tiny bit of corrosion was dropping 2 volts right at the terminal post. Cleaned that out and no problems since. So make it easy on yourself and clean your post connectors first. On the plus side I finally had an excuse to get that 160 amp alternator.....
Interesting. No codes, and I just cleaned the terminals a few weeks ago when I bought a new Diehard Platinum AGM battery. I guess I'll keep an eye on it and see if/when it acts up again. Hopefully it's as wwch99tj said and it's the alternator...good excuse to upgrade.
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Unread 06-15-2014, 09:31 AM   #5
pariah24
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2004 TJ Wrangler 
 
Join Date: Dec 2007
Location: Colorado Springs, CO
Posts: 157
Quote:
Originally Posted by wwch99tj View Post
Alternator is going bad, had the same problem a few years ago

Sent from my Galaxy Note 2 using my thumb
Just reminds of that saying...

"Jeeps don't break, they present you with opportunities to upgrade".
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