Current surge when heater grid cycles in my '03 HO

[tbush]

I've been experiencing a phenomenon in my 2003 HO truck for the last 2 winters that the dealer hasn't been able to explain. When I start driving to work in the mornings the radio will suddenly change radio stations, sometimes the volume of the radio changes... usually louder... . and this morning I also noticed a flicker of the lights on the dash along with the change in radio stations.



The symptoms coincide with the heater grid cycling so I'm guessing that this is causing either a current surge or a voltage spike in the dash harnessing. The dealer says that I may need to get the ECM reprogrammed. I haven't opted to go this route just yet.



Was wondering if anyone else out there is experiencing this sort of problem and if so how it was resolved.



Thanks,

TJ

 

[JWillms]

I have noticed that when I start my truck up every now and then I can see the dash lights and dome lights surge. I havent taken notice of outside temp but just now when I drove home it was 34 and I noticed it doing it again. I was hoping that it wasnt becuse I hooked up my guage lights wrong. Havent had my radio chage staions or get louder but my lights do surge.

Might sound dumb but jsut how do you tell when your heater grid cycles so I can see if its that.

Justin<><

 

[RonWeiss]

Guys,



I think there has been at least 20 discussions on this matter. Do a search and also look at FAQ's



Yes it's the heaters causing your problems



Ron W.

 

[rbattelle]

Ditto what Ron said, but I will add that it is completely normal. I usually try to sit at idle until the grids cycle, and I try to leave off as much as possible. Usually I sit there in the cold for the 2 minute cycle with only the parking lights and the radio on. Not only do my lights dim, but the changing load on the alternator causes a brief RPM variation as the ECM compensates for the change in load.

 

[dcscott]

Correct me if I'm mistaken but I don't believe the alternator is even active until after the grid heaters have finished cycling.



TJ, it is quite normal to have lights dimming while the grid heaters are on. The heaters draw a lot of power (in the neighborhood of 100 Amps). What seems different in your situation is your radio resetting, which is not normal.



The ECM keeps the alternator off until after the grid heaters have completed their routine. This is to keep the high current loads created by the grid heaters from burning up the alternator (I've seen several burned up this way on Cummings Marine diesels).



This means that all the power is coming from the battery(s). If the battery terminals are dirty, the connectors loose, the battery low on water, or the battery going bad, then the high current load will pull the voltage down and cause the radio to reset.



The problem of the radio resetting pretty much has to be in the battery system.



Dale

 

[rbattelle]

dscott,



Good point, I forgot the alternator is supposedly off while the grids are on. Nevertheless, the high current load on the batteries will tend to drop the voltage available to run other devices, such as lights and radios.



But if the alternator is off, why does my ECM have to vary fuel flow rate to maintain idle RPM when the grids are on?

 

[KBennett]

I think the solution to this problem has been stated many times here. Let the truck idle for at least 30 seconds before driving. I personally let mine idle for 2-5 minutes with the automatic high idler on before I take off. The truck runs so much smoother this way.



If the alternator is not coming on after the truck reaches 15 mph then you may have a problem. You can see it happen by watching the voltage gauge. It will be below 12V and when you start driving you will see it jump up to normal when you reach 15mph.



rbattle, my guess is that the fuel flow rate may need to change because of the injector supply voltage dropping or some other fuel control that is affected by voltage.

 

[rbattelle]

Actually, I think the reason the voltage comes up is that the heater grid cycle is cancelled above 20 MPH.

 

[chessie-system]

Greetings,

One other solution is unplug the relays that control the heater grids. The computer will get the truck started just like it is supposed to. I never used the heaters on my 95' and I disabled the ones on my 03' as soon as I got the truck. I live in PA and it gets close to zero here sometimes and the truck fires right up without plugging in or grid heaters with very little smoke. The heaters are mainly for emissions. You won't see any industrial applications with them on there. Also the batteries will be a lot happier without the grid drain. The original batteries on my 95' lasted 6 years by adding water every now and then and its mainly due to getting rid of the extra discharge source.



Jeff

 

[KBennett]

rbattelle, you can tell a lot more than I can with that super duper data display system but I still think the alternator is shut off during the heater cycles. Can you see the alternator amperage output with your system?



I think I'll leave my heater grid system in place on mine. I know it helps warm the truck faster

 

[rbattelle]

Oh heck, my system doesn't have any clue what the alternator status is. I have to rely on the gauge like everyone else.