Is this considered normal when starting the truck on a cold day, after it's been sitting all night? There are no switches on (air conditioning or heat or fan) and no other accessories, or my plow are turned on at this time. I generally like to let it heat up for several minutes before driving off.

http://www.youtube.com/watch?v=LnQItJA50u0


I've never seen this happen in any other vehicles I've owned. It only happens during warm up and after about a minute or two, it stops bouncing. It sounds like something, such as an A/C compressor is cycling, but with all of the engine noise drowning it out, I have no idea where it's coming from.

Hopefully the video is alright, as I've never uploaded any videos to YT before today


TIA for any advice / ideas on this.

 

That's just the grid heaters cycling. They pull a lot of juice. Perfectly normal.

Don't know why the sound of the motor changes though, that's kind of weird.

 

This is the grid heaters functioning. My THEORY is this is what causes so much of the voltage regulator failures on our trucks. The grid heaters are the closest thing to a dead short working against the battery and voltage regulator. Solid state sensing devices have little tolerance for shorted circuits. I have mine disconnected as I rarely drive my truck in the winter. If I were to drive in the winter I would add a cut out switch to the grid relay control circuit and just use them for the initial start and then shut them down after the initial start up, but that's me...

That's because of the heavy load being placed on the alternator. It loads the engine and slightly slows it down.

 

I just replaced the alternator and the fuel cutoff relay, as they were not functioning properly.. At first I changed the alternator, but realized that the relay was preventing the alternator from working, as per the sticky by wannadiesel.


I found it weird too, and at first I thought I was having some kind of alternator problem again, and all those bad words started coming out of my mouth.... until it stopped, and my blood pressure returned to normal


BTW, this is the first "Pick up" truck I've ever owned with a diesel motor in it. I have a box truck, with a 4 banger smoke motor, but it doesn't compare. I absolutely love the way this thing runs, and I swear to never own another gas powered Pickup again..... Runs like a train !

 

My truck does it too.. exactly like yours. I was gonna ask this question too but my vid didnt come out as good as yours. lol

 

Mine does that alsi sometimes, Never thought of the grid heater being part of it. I eat a lot of VR as well, if thats why it kind of makes me feel better. At least Its not some unknown gremin.

 

My gauge is much more casual about moving around the face, perhaps because it's a California truck (laid back? stoned?)

 

Interesting thought, my truck is moving to the bay area in a couple months, wonder if it will change its ways.

 

FWIW


For the first time, I plugged in the truck aboiut 6 hours prior to starting it. Not only did it start easier, but the fluctuation in the amp gauge didn't happen.


I guess I'll be plugging her in from now on....