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Discussion Starter #1
I have had pulsating light on this truck for a long time now. All lights pulsate even the buzzer cuts in and out. I thought a new alternator may help, but it only made it more noticeable. The only time the lights don’t flash is when the grid heater cycles, due to the draw, I think. Have any of you had any similar problems? I’ve added a few grounds with no luck. Any help would be appreciated!
 

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What year is your truck and do you have a external regulator on it?
 

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Discussion Starter #3
I once added an external voltage regulator and it only made the truck not charge, but the lights didn’t flicker. She’s a 93
 

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The alternator voltage is regulated by the PCM. Flickering headlights are usually a telltale sign of a bad rectifier in the alternator.
 

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You can't add a external regulator to a truck that the charging is controlled by the ECM unless you cut the 2 field wires off the alternator. Then you run new wires from the external regulator to the alternator.
 

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Discussion Starter #6
I shorted out the pcm a long time ago, every else is working mostly as it should. When I added the external regulator, I made my own field wires. I used a dodge external regulator and corresponding pig tail. It made the truck not charge, but the lights didn’t flicker. Maybe I didn’t do the field wires correctly.
 

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I shorted out the pcm a long time ago, every else is working mostly as it should. When I added the external regulator, I made my own field wires. I used a dodge external regulator and corresponding pig tail. It made the truck not charge, but the lights didn’t flicker. Maybe I didn’t do the field wires correctly.
Did you run a key on hot wire to one of the wires at the regulator? Was the regulator grounded good?

Another option would be a 1 wire alternator from https://www.paperformance.com/136a-denso-style-alternator-5-9-cummins-1-wire-2227se/
 

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Discussion Starter #10
Ok, sorry for not responding. So I went out and bought another voltage regulator. Same lick. This time; however,I decide instead of hooking the regulator to both of the exciter poles and a 12v accessory, but straight to the battery. This worked. But the question is are there any drawbacks or reasons I shouldn’t hook it directly to the battery?
 

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If you don't use a key on wire and go straight to the battery you'll drain your battery down when it isn't running. Most will use a relay and pull battery volts to the regulator so that it still turns on and off with the ign key.
 

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Discussion Starter #12
That’s what I did in the beginning, I use 12v accessory from the relay closest to the firewall. Pretty sure its a blue wire. But going straight to the battery is fine, especially if I add a toggle switch under the dash to cut power when not in use?
 

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That’s what I did in the beginning, I use 12v accessory from the relay closest to the firewall. Pretty sure its a blue wire. But going straight to the battery is fine, especially if I add a toggle switch under the dash to cut power when not in use?
If you can remember to turn the toggle on and off it would work ok but a relay would work better. Look at this Thread post no 1, the hand drawn picture shows how to wire it. https://www.cumminsforum.com/forum/89-93-non-powertrain/803281-external-voltage-regulator-rewiring-write-up-few-pics.html
 
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