Are the grids supposed to work when motor is warm?

[JCleary]

I've had my '03 H. O. QC for about three weeks, and I've noticed that the grids will cycle usually around 40 deg. , sometimes around 50 to 60 deg. temps outside. I figured that is normal.



What seems weird to me is that the grids will come on, even if the coolant temp is in the 160 range. I haven't noticed it at 190 (I'm guessing that's normal operating temp, just under the 210 mark). If it's mildly cold outside, they'll work, even with a hot motor. Is this normal?

 

[bpenrod]

Mine is like that too, if drive to normal operating temp then stop and run in a store or something when I fire it back up the grid will cycle a few times even with the engine temp up. Seeems like it takes it a minute to realize it is warm!

 

[gonzo2]

Yeah. It really has nothing to do with the function of the motor, they are just doing token attempts at keeping the smoke down to keep the EPA happy.

 

[Eric_77]

It is intake temp related if the inlet air is cool/cold the grids will heat to insure the fuel is burned. If you are driving without boost in cool temps you can see the grids cycle while driving even with coolant up in the 160-170 range.



EDIT grids only operate up to speed of 20-25MPH

 

[GWBourne]

ehh... im new to cummins and to modern diesel's... what are the grids? from the post i gather they are an air intake heating element?

is this correct?

thanks.

Grant

 

[BarryG]

GW that is correct that is exactly what they are. There are two of them and they each draw up to 90+ amps each which is why we have two batteries. They can cycle up to 180 seconds or as mentioned up to like approx 23mph. They recieve their input from a temp sensor , I think it is the one under the passenger side battery, not the IAT sensor. Which is why they can/will cycle even on a warm truck if the outside air temp by that sensor is low enough to trip them. At least that is how I understand it.

 

[Cummins4WD]

So that would explain why the interior lights and the dash lights dim a couple of times when the rig is first started... 90amp draw x 2... Thats a lot of load. Is the alternator suppost to be providing the juice after the truck is started or do they continue to draw off the batteries until the intake temp is warm enough or you go over 25mph?

 

[BarryG]

I may very well be wrong but I think our alternator is only 140 amp. So the batteries are making up the difference once the truck is started.

 

[Yo Hoot]

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[GWBourne]

GW that is correct that is exactly what they are. There are two of them and they each draw up to 90+ amps each which is why we have two batteries. They can cycle up to 180 seconds or as mentioned up to like approx 23mph. They recieve their input from a temp sensor , I think it is the one under the passenger side battery, not the IAT sensor. Which is why they can/will cycle even on a warm truck if the outside air temp by that sensor is low enough to trip them. At least that is how I understand it.

ahhh, i see. the pic below is the intake horn correct? seems a bit like an intake baffle if you live in a warm climate...



thanks again for the info. learn something new everyday.

grant