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GMC 2007 Roadtrek 6.0L 145 amp alternator. Battery warning…

GMC 2007 Roadtrek 6.0L...

GMC 2007 Roadtrek 6.0L 145 amp alternator. Battery warning light on, volt output 11.7 volts; intermittent problem; equipped with dual battery isolator, sometimes it self corrects and voltage goes to 14, and battery warning light goes off?

Mechanic's Assistant: Just to clarify, what are the exact lights you're talking about?

Battery warning light on the dash, and voltage output on the dash

Mechanic's Assistant: What is the model of your '07 GMC?

3500 chevy express

Mechanic's Assistant: Are you fixing your Express yourself? What have you tried so far?

Tried nothing thus far; in factory condition at this point

Mechanic's Assistant: Anything else you want the mechanic to know before I connect you?

Its a Roadtrek with a dual battery isolator. thanks for your help

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Answered in 25 minutes by:
1/30/2017
xsvectOR
xsvectOR, ASE Certified Technician
Category: GMC
Satisfied Customers: 17,338
Experience: car expert!
Verified

sounds like a intermittent voltage regulator issue...i would rebuild or replace the alternator...

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Customer reply replied 1 year ago
Sounds like a plan. Its a GMC CS internal regulator. Any ideas about voltage regulator excitation, or sensing circuit? Thanks for your help.

its internally regulated.....

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Customer reply replied 1 year ago
internal regulated Delcotron GMC 145 amp connected to a dual battery isolator; engine bat and coach bat; works sometimes and then goes kooky other times
Customer reply replied 1 year ago
the alternator is a four wire coming out the top

what chassis... savana?

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Customer reply replied 1 year ago
3500 chevy express

thats the diagram that listed for a 3500 express

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Customer reply replied 1 year ago
Thanks for your help! I'll see what happens. I'm wondering about PCM and ECM interface with the regulator. Any ideas?
Customer reply replied 1 year ago
Any past experience with ECM or PCM affecting regulator function?

the pcm does work in conjunction with the alternator,,,,never seen a pcm failure tho for this concern...

xsvectOR
xsvectOR, ASE Certified Technician
Category: GMC
Satisfied Customers: 17,338
Experience: car expert!
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xsvectOR and 87 other GMC Specialists are ready to help you
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Customer reply replied 1 year ago
Thanks for your help! Have a good night.
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