Voltage Drop / Lights Dimming on Cold Start

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It's time to "sticky" this one at the top of the forums again.

If this describes what you're experiencing when lighting off the Cummins on these frosty mornings,.......
Don't worry, it's normal.

The Cummins uses a pair of 12 volt grid heaters in the intake tract
(imagine two large toaster elements glowing bright red)
that preheat incoming air for easier combustion.
The Ford & Chevy use glow plugs inside the combustion chamber.
As the relay cycles the grids on & off, the large amp draw causes the volt meter reading to drop, and the lights to dim when the relay turns on the juice.
The relay timer will turn off the heaters when the intake temps hit a preset limit, or when the vehicle exceeds a preset MPH (usually between 15-25 mph). edit



Thats kinda of interesting, cold air to be heated before entering the combustion chamber while truck is running, then Why are there huge intercoolers on the front of these trucks to cool the air entering?
I think the intercoolers are to drop the pressurize air temp.

Still scratching head.

Not trying to fire anyone up, just thought it was kinda interesting.

I drove my truck several hundred miles at least long enough it should have been plenty warm and when I pulled into a rest stop the lights would dimm and the voltage meter would drop as if the alt was kicking on an off.

wierd truck this here dodge.

BTW I am dropping it off at the service dept, I just know they are going to try and tell me my problems are because of the edge juice. even though the truck had all of these problem before the edge.

 

were you running your defrost setting on the blower? Our trucks cyle the A/C compressor during defrost, and if you are having fueling/power problems, or a worn A/C compressor, you will see the lights dim due to the engine drag slowing things a bit plus the A/C clutch taking juice.

 

i would rather have the air intake heater then glow plugs that seize and break off in the head.....or faulty glow plug controllers...an intercooler drops the temp by roughly 200 degrees and the turbo is responsible for pressurizing the air not the intercooler. u think glow plugs dont draw amps either ? they operated the same exact way and are associated with having more problems......u can hard wire a switch to operate the heater grid only on startup...if that is your problem, or ucan dissconnect it entirely u might have a sticky $10.00 relay....pull the heater relay and replace it with a new one

 

Could you tell me a little more in detail how to hard wire the heater grid?

I have this probelm with ac blower on and off even with all electrical off.

 

the heater grid sits under the air intake horn, youll see 2 elecrical wires going into it....splice a switch into the hot lead. allways use a fuse and proper gauge wire......id be on the safe side and use a battery cutoff switch as well as battery cable cauze those are some heavy duty wires. i would first check into switching out the relay easiest thing to check. as the grid heater ages u might notice a large amp draw due to higher resistence in the element, and u should look into replaceing it. u can measure resistence across the two terminals as the grid is cycleing...compare the numbers to factory specs which i dont know......if the resistence is way outa whack u need to change the grid, should take no more then 30 mins.....try changing glow plugs that fast

 

The grid will come on if the intake air temp is below a certain value and the engine is at idle or near idle. (low vehicle speed, low engine speed, low load) The warm air intake at this situation helps to burn the fuel better and reduces emissions and carbon buildup at the exhaust valves. The only downside is that it's taxing on the batteries and the alt.
Under boost when very hot air is coming from the turbo the charge air cooler helps you to get cooler (denser) air in- but this only happens when you've got boost, meaning you've got RPM and load on the engine and therefore the problems with carbon buildup and incomplete burn due to insufficient pressure and temperature of the air charge do not arise.
That's why we have an intercooler and electric grid heaters even though it sounds a little weird at first.- They simply won't operate under the same conditions. Kind of like having AC and a stove in the same building to keep you in the comfort zone.

AlpineRAM