7.3psd voltage fluctuation
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2nd Gear
Joined: Dec 2023
Posts: 2
Likes: 0
7.3psd voltage fluctuation
On the way to work today my voltage dropped down to around 12 volts. I figured it was the alternator, but on the way home it went back to 14.2 and started fluctuating between 12 and 14. Could it be the GPR? I replaced batteries and alternator recently and redid the wiring that hooks to alternator.
More Turbo
Joined: Dec 2002
Posts: 664
Likes: 129
From: Columbia, MD
12 to 14.2 sounds like battery voltage (no alternator) versus alternator. Glow plugs will drop it a LOT more. Lots of possibilities; rechecking all your connections is a good place to start. I had a boat do something similar, the metal O-ring on the alternator positive connection fractured but looked like it was still attached until a tech tugged on it. Moral... check all the connections before condemning any parts. Especially ones that you touched recently. This includes the connector to the top of the alternator that is vulnerable to people, tools, and other weighty objects resting on it and fracturing the wires.
Cargo Master
Joined: Apr 2012
Posts: 2,033
Likes: 535
From: Bottom Of Pikes Peak
If you were driving, it wouldn't be GP's. It could very well be a failing Alt. Easy enough to test with a multimeter unless it's intermittent.
it could also be something as simple as a connection as mentioned.
My voltage is always over 13.5v to 14.4 while running
it could also be something as simple as a connection as mentioned.
My voltage is always over 13.5v to 14.4 while running
Hotshot
Joined: Dec 2005
Posts: 10,256
Likes: 7,694
From: Chino Valley, Arizona
12 to 14.2 sounds like battery voltage (no alternator) versus alternator. Glow plugs will drop it a LOT more. Lots of possibilities; rechecking all your connections is a good place to start. I had a boat do something similar, the metal O-ring on the alternator positive connection fractured but looked like it was still attached until a tech tugged on it. Moral... check all the connections before condemning any parts. Especially ones that you touched recently. This includes the connector to the top of the alternator that is vulnerable to people, tools, and other weighty objects resting on it and fracturing the wires.
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2nd Gear
Joined: Dec 2023
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I checked all the connections and grounds, everything looks fine. While I’m at idle it will sit at 14.2 volts then drop to 13 and when I rev it it hops back up. Other times it will get as low as 11.7 and not go up when reved. there’s no pattern I can see. The only ground I haven’t checked is the engine ground, I’ll go look again soon.
More Turbo
Joined: Dec 2002
Posts: 664
Likes: 129
From: Columbia, MD
Sounds like it's not responding to change in load / RPMs very well. I would be leaning towards the voltage regulator and its connections... or the serpentine belt? Is the belt tension good? If belt slips under increased RPMs, it may cause issues for alternator.
Lead Driver
Joined: Apr 2016
Posts: 7,221
Likes: 1,342
From: Bahstun
the exciter wire like to get loose from leaning on it when working in the engine bay
i bought a new pig tail and it solved it for me.
try to wiggle it while running and see if volts drop
i bought a new pig tail and it solved it for me.
try to wiggle it while running and see if volts drop
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Hotshot
Joined: Oct 2003
Posts: 17,799
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From: Ashland City, TN
The plug that reads the voltage on these things really likes to be screwy. They generally are loose, or having an issue.
But if you're going between 12 and 14, that usually means something going wrong with the alternator.
I've been seeing some weird stuff like that though out of my recently replaced reman as well.
But if you're going between 12 and 14, that usually means something going wrong with the alternator.
I've been seeing some weird stuff like that though out of my recently replaced reman as well.
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