10.85 volts with engine running?
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Posting Guru
Joined: Jun 2008
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From: Albuquerque
10.85 volts with engine running?
Slow to start this AM, (actually noticed this Sunday comming out of the woods after camping this weekend, did have the music going, but was careful not to run it down). When it started, I checked voltage at both batts and was only 10.85/10.84. SES light was on for a couple minutes. Batts are 9 months and upper alt is 9 months. I will check ALL connections for cleanleness and tightness, but initial thought is the upper alternator. I had this replaced under warrintee 9 months ago at the dealer, but my warrintee is out and so is the alternator warrintee (12,000 miles). Am I on the right track? Oh, its 90 miles back to the house with no batt light, just didn't appear to recharge.
Thanks
Thanks
Post Fiend
Joined: Feb 2007
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From: Dallas-Ft. Worth
Mine sits around 13.7-14.2V after first starting & the glow plugs are done. That's even with headlights on & AC fan running.
And yes, you're on the right track, but you have that whole dual-alt thing most of us don't have. Might make sure the associated electronics are doing what they're supposed to...
And yes, you're on the right track, but you have that whole dual-alt thing most of us don't have. Might make sure the associated electronics are doing what they're supposed to...
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Posting Guru
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From: Albuquerque
Thanks for the response.
Joe, when this happened last year, I could never get a good answer about that second alternator. I've "heard" that its not tied into the charging system but is there for accessories? Doesn't make sense to me, how else would it know when there is a draw for it to start powering up?
Joe, when this happened last year, I could never get a good answer about that second alternator. I've "heard" that its not tied into the charging system but is there for accessories? Doesn't make sense to me, how else would it know when there is a draw for it to start powering up?
Elder User
Joined: Mar 2003
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From: northern Michigan
I would run the alternator to an auto electric shop. They can rebuild the one you have for less then a new rebuildt one and it will probably last longer also. Make sure they know it is on a diesel as the regulator is different in a gasser.
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Posting Guru
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From: Albuquerque
UPDATE: Cleaned everything (minor corrosion), made sure everything was tight, charged both batts up to 12v, got truck running and checked voltage from big post on alternator to positive post on batt = zero volts. Is the alternator shot?
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Lead Driver
Joined: Jul 2005
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From: Eccles, WV
From the big post on the alt to the pos post on the bat will read 0. Read voltage from the big post on alt to ground.
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Hotshot
Joined: Jan 2008
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From: Rochdale MA
You need to check form the big post on the alt to ground. You will get 0 volts where you tested because you are testing positive to positive.
Posting Guru
Joined: Jul 2004
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From: Buckingham, IA
You got it. Time to get the alternator replaced. The reading that you are getting from the alternator is coming from the batteries since the alt. isn't putting out any power. I've come to the conclusion that a used OE alternator from a "recycling" yard is better than a rebuilt one from a parts house. Even if you would have to get an OE one rebuilt, it would still be better and maybe cheaper.
Elder User
Joined: Mar 2003
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From: northern Michigan
Actually he would have read the voltage drop across that area. in this case zero volts is good, means no voltage drop and good connections. To test alternator output you need to read from ground to alternator output post and should read around 14vdc if everything is kosher.