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I think I have a bad alternator when I 1st start my truck for about 15 minutes or so all of my lights pulse from brite to dim. Is this sign of a bad regulator in the alternator? It's a 17 Ram 3500 desiel with the single 220 amp alternator
 

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I have a sneaking suspicion that it's just your grid heater cycling... Could you post a video?
 

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Thanks guys I'll try to upload video tonight after work I can't seem to figure out how to do it on this stupid smartphone
 

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I just had this happen to me this morning. I also noticed a “click” sound coming from the passenger side dash area whenever it would pulse.
 

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Blah ha ha ha, when i saw the title i was thinking it would be a post from someone asking how to wire up lights that pulsate with music! I was ready to get my torch out.
 

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Discussion Starter #7
okay i finally figured it out my phone creates mp4 videos and this program only allows wmv format videos. this taken at 4:30 am Feb 13/2017 and the temp was -17C which is 1 degree F and the truck was not plugged in and was remote started
 

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Again, it's your grid heater.

Some trucks use glow plugs, the Cummins uses a grid intake heater. It pulls a fairly large electrical load, hence the lights dimming when it cycles on and off. Its 100% normal. It's what allows you to start at cold temperatures by heating up the air going into the motor to aid with combustion.

Speed up past 15mph and it should turn off.

If you normally plug it in, then you probably haven't noticed it as it usually doesn't need the grid heater after being plugged in (unless it's extremely cold).
 

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Once Again thank you for all your help...... I've never experienced this before, so its true you can teach an old dog new tricks LOL
 

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Thanks guys I'll try to upload video tonight after work I can't seem to figure out how to do it on this stupid smartphone
I’ve never been able to make it work either. No matter if it’s smartphone or computer/laptop. One of the other members suggested that you upload it YouTube and just post the link in here. That’s what I’ve done in my passed posts. Seems to work better and be less frustrating than trying to figure out how to upload it straight here.
 

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Grid heater. Normal. The click you are hearing is the grid heater relay contacts.
 

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Why would the grid heater cycle after the truck is started?

My truck is doing the same thing. You can also see the voltage drop to 10 volts and then cycle back up to 14 volts when it's clicking. It's starts fine, but then for the first few minutes it cycles as described.

I'm suspecting the alternator.
 

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Why would the grid heater cycle after the truck is started?

My truck is doing the same thing. You can also see the voltage drop to 10 volts and then cycle back up to 14 volts when it's clicking. It's starts fine, but then for the first few minutes it cycles as described.

I'm suspecting the alternator.
The gird heater draws an very high amount of current (95 amps per element), thus dimming the lights until it goes off. What sorts of outside temperatures are you seeing right now? Does the light dimming stop once you start moving?
 

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Why would the grid heater cycle after the truck is started?

My truck is doing the same thing. You can also see the voltage drop to 10 volts and then cycle back up to 14 volts when it's clicking. It's starts fine, but then for the first few minutes it cycles as described.

I'm suspecting the alternator.
Don't take this wrong, BUT, I'm suspecting the issue is reading comprehension and not the alternator! It's your grid heater!!
 

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Don't take this wrong, BUT, I'm suspecting the issue is reading comprehension and not the alternator! It's your grid heater!!
Thanks!!

This is the first time it's been doing it in 160,000 miles and though all temperatures. Never been a problem before, so why would it start now? If it is the grid heater, which it could be for sure, what changed to make it dim the lights and change the voltage now?

The truck has new batteries about a month ago. After the truck has warmed up for a couple of minutes it stops, and shows a constant 14 volts.

The outside temperatures have been hovering just below freezing.
 

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Definitely grid heater. On my 2003 (that had a voltage gauge) it would make the gauge look like a windshield wiper untik the cycle completed.

The heater cycle starts when you turn on the key (the wait to start light is the indicator)

After the startup, the grid heaters again cycle until the engie warms to a certain point. I've never monitored (nor researched) what drives this--whether it's intake air temp, oil temp, coolant temp, or what.

Engaging your exhaust brake will shorten the warm-up time. I've aso found this to be variable...to the point that it'll come up to full operating temp (as judged by ECT) quicker in cold weather than in warmer weather using the e-Brake....or it might just be in my head.

In cold enough weather, at idle, the grid heater may re-engage, or so I've read. Usualy the automatic high-idle is enough to keep 'er running, but I've been told the grid heaters can kick in too.
 
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