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Unread 07-23-2015, 07:58 PM   #1
FrontierGander
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1973 CJ5 
 
Join Date: May 2014
Location: Boncarbo, Colorado
Posts: 90
AMP light is on

Ok its a 1973 CJ5 with a rebuilt 258, 3 speed. New alternator.

This just happened recently but the AMP light turned on, went off, turned on. Didn't pay much attention because the jeep had sat for a month due to horribly made new replacement parts we get to enjoy these days. Once the new rollover valve and sending unit was it though, I've been driving it daily and the light just never shuts off, even during 65-70 MPH speeds.

Checked at the battery and its putting out (At idle) 14.28 volts and with the lights on, 13.50 volts.

I thought maybe a voltage regulator but after getting the readings, it doesn't make sense for the AMP light to be on.

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Unread 07-24-2015, 03:48 AM   #2
Matt1981CJ7
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1981 CJ7 
 
Join Date: May 2011
Location: Elbert, CO
Posts: 13,642
Sounds like your new alternator was wired wrong.
Or you have a grounding issue.

Is this alternator externally regulated?

Matt
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Unread 07-24-2015, 05:41 AM   #3
steve1973
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1973 CJ5 
 
Join Date: Jan 2012
Location: Charlestown, Rhode Island
Posts: 202
On my 73, if the amp light goes on and I know everything else is sound, I check for breaks in the wires from the alternator and external voltage regulator. It has happened twice and the brittle old wires were the reason.
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Unread 07-24-2015, 09:45 AM   #4
FrontierGander
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1973 CJ5 
 
Join Date: May 2014
Location: Boncarbo, Colorado
Posts: 90
yes external regulator. Looking into doing a swap down the road because I am going to be adding a winch shoot and that 35-37 amp alt just isnt enough.

I'll check the wiring out and see.
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Unread 07-24-2015, 11:51 AM   #5
zillla
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1975 CJ5 
 
Join Date: May 2009
Location: Wyoming
Posts: 1,176
Is it the stock Motorola Alt?? Mine crapped the bed so I swapped in a CS 130 Delco alternator. The Motorolas are crap..
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Unread 07-24-2015, 01:38 PM   #6
FrontierGander
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1973 CJ5 
 
Join Date: May 2014
Location: Boncarbo, Colorado
Posts: 90
not sure, its a refurb off ebay. Everything is charging great, just the light is in.
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