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sksmith's avatar
sksmith
Explorer
Sep 24, 2014

alternator problems

Its on a 1995 Safari. 300 cumm. Alternator now charges and tac and volt gauge kicks in but after 20 seconds the tac drops out for a split second then comes back on. The voltmeter flutters at same time. More to the story is the alternator didn't have a hot wire to the exciter side of it. I ran a new wire from the ignition to alternator. now the tac and voltmeter work but drops off every 20 seconds over 1000 rpm. at idle 600to 700 rpm it goes for about 35 seconds. It only drops for a split second. Help before I go crazy.
  • En breve I will tell you what is happening. Why it is happening is also apparent to me but the answer or explanation will confuse the hell out of you and I will spare you the agony.

    What you require is "The Fix". I want to make certain that needless wires are not running hither and yon skewing with the voltage regulator sensing.

    J180 foot alternators are designed to work with just two big wires, the 3rd little wire is the tachometer sensing wire. Enough for now.
  • You need to go to (free) photobucket online and get an account. Do that and come back

    http://www.photobucket.com

    my email is well known so it isn't private...

    mexbungalows@gmail.com
  • The battery isolator does have fins. I have pics of the isolator and alternator wiring. But I don't know how to post them.
  • Can you take an image of the unit and post it here? From Delco 21SI to Leece Neville Road Handler, to Niehoff, the connections differ and it is vital to determine which is which.

    You are getting a loss of stator output signal. Charging has stopped. Important to determine is cause is alternator internals, wiring hookup, or a miswire with a silicon rectifier battery isolator. Without info suggestions are guesswork, a hundred possibilities.

    Second issue, does your Safari have a finned-box with studs battery isolator
  • Batteries tested at 12.2 volts with a volt meter. When alternator is charging it reads 14 volts plus.
  • The alternator has a two spade plug on the under side one is a direct hot from batteries the other side is what I was told is a exciter to open a rectifier. The back of alternator has three wires one a ground one goes to battery isolator and a small one that is red and goes in a wiring loom never to be traced out????
    The original problem was the tac and voltmeter quit working and there was no wire to what I call the exciter side it did have the direct hot wire. Alternator has been tested and all is fine.
  • Tell us more about the original and new alternator wiring:

    B+ to center lug of battery isolator I suspect.

    You mention an exciter terminal on the alternator. Are you sure it is not an external SENSE wire that goes to the chassis battery terminal of the battery isolator?

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