Voltage fluctuation
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Scope Wizard
Joined: May 2019
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best way is to use a scope on the output of the Alternator, but you could also set your meter to the AC scale and check voltage on the batteries and IF you see any AC voltage it is a sure sign of a failing diode.
EDIT: here is a link to help understand this https://www.motor.com/magazine-summa...-ripple-effect
EDIT: here is a link to help understand this https://www.motor.com/magazine-summa...-ripple-effect
Lead Driver
Joined: Apr 2008
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Dont think ive seen this issue with a 1g alternator, i know the 3g can do it when the regulator starts getting tired, brushes as said can also do it. Does it bounce back and forth or one for a while then the other?
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Posting Guru
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I'm curious if while running, hook a multimeter up to the battery and see if it follows the same fluctuations. If it does place your hand on the regulator and see if it's hot.
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I saw a whisper of smoke in the area of my regulator. I was not in the truck so I was not monitoring voltage but the short drew down my batteries so check for amp draw between cable and terminal of battery or disconnect batteries if you are going to let it sit. I replaced VR and all was fine initially, 13.5V at idle but then it jumped to 14.5 and my battery light is flashing which is new. I replaced the alternator with a reman unit also so I need to start over and check everything. My VR was a carquest bargain old stock so maybe it is cow****. I am not sure what the difference is between the S and T models of the VR either.
89F250
89F250
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Ran through the manual tests. It is a bit of pain if you are alone but with my battery light stuck on and good charging voltage at the batteries I was confused so I just followed the steps in the manual. It seemed to pass the load test fine so I kicked ahead to test the S terminal at the regulator connector and that seemed to be the problem. New AZone regulator and battery light is off and charging voltage seems to be stable. I guess the $14 carquest ebay EVR was no bueno. I had changed the alternator just because the old one was unknown but I saved it. New one seems a bit noisy so I will monitor that. Anyway, progress.
Front take is clean and back in place with mesh filter/hose fix and new sender. Chinese fuel switch is working and truck is starting nicely now, although it is not cold.
Mike
89F250
Front take is clean and back in place with mesh filter/hose fix and new sender. Chinese fuel switch is working and truck is starting nicely now, although it is not cold.
Mike
89F250
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The fender plate the voltage regulator mounts to has a ground wire, because otherwise it's ungrounded (just bolted to the fender liner from underneath) make sure it's clean.
On anything with an external voltage regulator I always add an extra ground just for the hell of it, but Ford kinda already has that, just clean up the mounting screws and holes on the plate when you install it.
On anything with an external voltage regulator I always add an extra ground just for the hell of it, but Ford kinda already has that, just clean up the mounting screws and holes on the plate when you install it.
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Aye, makes me doubt whether I had that ground hooked up after I replaced the fried EVR so then I damaged the new one. Makes sense. On my truck the ground strap is attached from the firewall to the fender and the smaller ground wire from the fender is hooked up to the EVR.
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