What is causing the electrical system to pulse at a rate of about 240 cycles per min.
I first noticed this in the dash lights, and head lights, but it seems to be pulsing all of the electrical system.
My grid heaters are disconnected, I have checked and cleaned all grounds I can find.
This did seem to start shortly after I installed new NAPA Batteries.
Could the problem be in the Multy Function switch?
Is the voltage regulator in the alternator?
I have looked and searched this site and more, and have not found the problem.
2008 Dodge 3500 deleted.
Thanks

 

This morning they pulsed all the way to work (about 6 miles) when I pulled up at work, it stopped pulsing. If I turn on the lights, it will pulse for a moment and stop. If I let the window down it will pulse for a moment and stop.
I think it is the ECU (regulator) in the computer causing the alternator to pulse.

 

Your grid heater isnt doing something wierd is it? I noticed mine doing that when its cold on its first start. Not that many times but cycles for a minute or so. Maybe your relay or something is acting up?!?!


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I've owned this truck since this past May. This morning after cranking lights dimmed down and the needle indicated a swing down to about 10 volts. Then it would go up to about 15 and bright lights. It even did the swing while I was holding the rpm's up to about 1K. going down the road all works fine. I dont understand why a computer would be pulsing the alternator. Also, I would think the regulator in the alternator would work or it would not...Any Ideas??

Thanks

 

That's your grid heater cycling on and off...perfectly normal.

 

I'm not sure what the grid heater does unless it has something to do with the Fuel. would the heater still be doing this after driving 30 miles this morning? It was about 40 F this morning. When I first cranked it the swing was not much on the needle. After getting to work (34 miles) the swing was more and idling up the motor did not stop it like it did in my driveway. Going down the road it works fine. I have alot to learn on these trucks...Thanks!!

 

after 34 miles the alt should not be making the needle swing like that mine will only swing back and forth for 90 seconds if i let it go that long but it will stop once i hit 20 mph i would say you either have a stuck switch or the alt is getting ready to crap out on you also why is your grid heater disconnected? hook it back up and see if that helps might be the computer trying to make them work and not seeing a voltage to them so it keep doing it

 

what I failed to say was after 34 miles I turned off the motor and waited 2 minutes and cranked. At that point I didnt know about the grid heaters. It started the timer again...Thanks for all the help. It was operator error.

 

I am new to my truck and have noticed the grids working in the cold. It aids in start up but have noticed that they can sometimes run later. I was told they not only help in starting but help emissions as well. I noticed the other day they cycled for a minute or 2 at start up. I drove for a bit and stopped at a place for 10 minutes. Truck was never up to running temp and I noticed the heaters cycling as I left that place. My alternator gauge doesnt move around when the grids are working. The need is low on the gauge maybe 11oclock position. Stays there until grids stop and then it moves up to 1pm position where it appears to be the normal position.

My old Chevy 6.2 years ago would cycle glow plugs. The glow plug light would come on and off each time the plugs cycled. Thing I have noticed on the Dodges are the grid heater light only comes on during startup.

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The grid heater light does not come on with the engine running even thought the grid heater does cycle until the intake comes up to some pre determined temperature of which I'm not sure of.

 

Your grid heater should come on when the block temperature is below 60* is what I have heard. The heater warms the air coming in to aid combustion. When the heater cycles on and off you will see lights dim and your gauge drop.