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| | | | Joined: Feb 2020 Posts: 24 'Bolter | | 'Bolter Joined: Feb 2020 Posts: 24 | I installed an LED alternator warning light in my 1949 chevy 3100. I ran the warning light wire from the alternator to one side of the bulb and ran one from the ignition switch to the other side. Everything I have researched shows this to be correct. The problem I am having is the light stays on but it is dim. When I turn the key, the light is bright but then goes dim after the motor starts. i put a meter on the battery and it does jump from about 12.5 to 14.5 when started. I checked resistance to ground with the alternator warning light unplugged from the alternator and it checked out ok. I'm struggling with this one and would really like to put it behind me. Anyone have any ideas? It is a brand new alternator and a brand new battery.
Thanks
Corey
1949 chevy 3100
Scotts IFS
4-link rear
L-31 5.7l vortec
| | | | | Joined: Aug 2019 Posts: 242 'Bolter | | 'Bolter Joined: Aug 2019 Posts: 242 | I also had this problem.
It seems the regulators on many alternators are configured to control an incandescent bulb rather than an LED.
They raise the voltage on one side of the bulb, but not enough to turn off an LED which will still illuminate under a small voltage difference.
I bet if you swap in an incandescent it will be fine.
'59 Chevy Suburban, NAPCO
| | | | | Joined: Aug 2018 Posts: 1,004 'Bolter | | 'Bolter Joined: Aug 2018 Posts: 1,004 | You could try to put 100 ohm resistor across your LED to simulate the load of a small incandescent bulb if you want to keep the LED | | | | | Joined: Feb 2020 Posts: 24 'Bolter | | 'Bolter Joined: Feb 2020 Posts: 24 | Why didn't I ask you guys days ago! Thanks for the replies guys. I might try the resistor first since I really like the little LED with the battery symbol on it.
1949 chevy 3100
Scotts IFS
4-link rear
L-31 5.7l vortec
| | | | | Joined: Feb 2020 Posts: 24 'Bolter | | 'Bolter Joined: Feb 2020 Posts: 24 | The resistor worked like a charm! Thanks guys.
1949 chevy 3100
Scotts IFS
4-link rear
L-31 5.7l vortec
| | | | | Joined: Mar 2010 Posts: 10,270 Renaissance Man | | Renaissance Man Joined: Mar 2010 Posts: 10,270 | When I was a young lad, I was putting together one of those pocket radio kits popular at the time.
It came with an led bulb to indicate when it was on. I happened to grasp one of the wires of the led and one terminal of the 9 volt battery and the bulb glowed a little bit.
It freaked me out than, and it still does now.
1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission
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