05 3500 4x 4dr long bed DRW 100,000 miles- About a year ago when towing the Jeep on the trailer and the camper on, get the chime to check gauges, volt meter is pegged full left.

Pull over at the next easy pull-out, turn it off and then re-start it, voltage is roughly 14.x and all is fine, never happens again until two days ago. Wife phones from the road locally and relates the same. I tell her to pull over, turn it off and re-start it which she then relates fixes it short term and then it happens a few more times until I take it for a drive and the restart won't get it charging again.


Fortunately I just installed a pair of Platinum Diehards, so the trip back from OC was able to be made just on batteries alone. I picked up and installed a reman alternator from NAPA after leaving it on the battery charger the previous night and most of the day.

When I started it afterwards, the VM showed slightly below 12 and then finally kicked over to +14 or about where it normally sits.

I had the driver's door open and the dome lights were on and I observed them dimming and then going back to normal brightness at about 15 second intervals which confused me, so I hopped on here last night and did some searching around trying to find something similar to explain what I was seeing.

I found several references to the grid heater cycling and since I thought it may be the PCM getting used to the new alternator, I didn't pay much attention to the dimming.

Is the cycling normal? If not, is the grid heater malfunctioning what killed the alternator? I'm in SoCal and ambient was slightly below long sleeve shirt and above short sleeves or about 60 degrees or so and the truck had been sitting on the charger all day, so it wasn't warmed up.

Batteries are new, cables are very clean, terminals were brushed to shiny when I installed the batteries, no corrosion, good observation of cables and wiring don't reveal any chafing, wear, or much of anything externally to indicate a problem related to that.

Normally I would believe the alternator just died, but my past experiences indicate that when one dies, it's not able to be kicked back to charging by cycling the run/start and do that a few times before it totally gives up the ghost. This one would charge for a few miles/minutes and then drop off enough to kick the warning chime on which lead me to believe it may have been the regulation circuit in the PCM acting up.

Some clarity would be appreciated.

 

I've noticed something odd but, nothing quite like yours. I've noticed mine will show something on the order of 11 volts for the first few minutes after starting in the morning. After about 5 minutes, the Voltmeter rolls up to the normal 14.7 volts.

I replaced my batteries last summer (50K miles) since one was showing signs of leaking. I suspect, it was being drained a little more than it should in the morning before being charged to it's normal state.

Oh, I'm in the Ventura CA area so, weathers about the same.

Keep us posted.