Alternator indicator light

Charging, starting, lighting, gauges, HVAC

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surveyor ryan
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Alternator indicator light

Post by surveyor ryan »

I need a little help with the location of the alternator indicator light. I've got a 72 f250 4x4 and I'm chasing a no charge situation and was directed to that light. If its burned out or removed I'm told the alternator doesn't know its supposed to charge and I've looked everything over and that's where I'm at. I can't seem to find an image showing me where the light is and since I've never seen it illuminated I could sure use some help before I blindly poke around under the dash
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sargentrs
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Re: Alternator indicator light

Post by sargentrs »

I believe '72 had an option of either gauges or idiot lights. Both should be located in the same position whatever it had. In the case of the alternator, it would be lower left corner. http://www.fordification.com/tech/image ... upanel.jpg
Randy
1970 F100 Sport Custom Limited LWB, 302cid, 3 on the tree. NO A/C, NO P/S, NO P/B. Currently in 1000 pcs while rebuilding. Project thread: http://www.fordification.com/forum/view ... 22&t=59995 Plan: 351w, C4, LSD, pwr front disc, p/s, a/c, bucket seats, new interior and paint.
1987 F-150 XLT Lariat, 5.0/C6 auto.
surveyor ryan
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Re: Alternator indicator light

Post by surveyor ryan »

So its either the light or the gauge but not both? If that's the case will the gauge not being hooked up have the same effect as a burned out bulb?
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sargentrs
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Re: Alternator indicator light

Post by sargentrs »

Yes, either/or not both. Here's a good explanation of how the voltage sensing circuit works. http://www.fordification.com/forum/view ... hp?t=59765 What is making you ask? Alternator not charging? Gauge not working?
Randy
1970 F100 Sport Custom Limited LWB, 302cid, 3 on the tree. NO A/C, NO P/S, NO P/B. Currently in 1000 pcs while rebuilding. Project thread: http://www.fordification.com/forum/view ... 22&t=59995 Plan: 351w, C4, LSD, pwr front disc, p/s, a/c, bucket seats, new interior and paint.
1987 F-150 XLT Lariat, 5.0/C6 auto.
surveyor ryan
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Re: Alternator indicator light

Post by surveyor ryan »

Exactly, alternator not charging. I feel its probably the alternator doesn't know its supposed to charge due to an issue with the exciter wire that post discusses. I read in another post that if you pull the orange F wire and hold it to the positive battery terminal with the truck running you see if the alternator is bad. The voltage went from 12.5 to 14.8 so the alternator can charge its like it just doesn't know it needs to. This is why I'm looking at the light being the problem perhaps. I was told to test the voltage at the green with red stripe wire and see if you've got 12v and if not there's my answer. I can't mess with the truck til Friday and will try that then
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