Cold weather issue?

[BWeidlich]

I have an 05 model. In cold weather when I start it up, for about 15-20 minutes the interior lights and headlights go from bright to dim, the heater fan speed goes up and down and the voltmeter reads a little low. I do not notice this in warm weather. After about 15-20 minutes the voltmeter goes up to normal and everything is fine. Just curious if anyone else has experienced this and is it normal?

 

[brista]

It is your grid heaters cycling but I don't think they should cycle for 15 minutes.

 

[BWeidlich]

Is this something that should be looked at or is it normal?

 

[jelag]

You've missed several threads on this... . during very cold weather the heat grid on the intake air turns on and off until the engine reaches a certain temperature... . Thats one of the reasons you have a wait to start light... This heat grid is warming the incoming air to speed engine warm up, increase fuel burn, and keep the engine from smoking and finally meet emissions... .



This grid draw a lot of current... . I'm guessing 80-90 amps or so and also during this cold start process the alternator is not giving you much output if any... . so when the grid heater comes on, everything goes dim and when it cycles off every thing come back bright... ...



You can avoid this if you plug your truck in at night or put it on a timer for 1 or 2 hours before you start... . I run a short power cord from the front of the truck to the crack between the fender and bumper on the drivers front wheel... that way when I walk out I can see the power cord and don't drive away with it plugged in.....



Hope you enjoy your truck...

 

[MN Cummins Lvr]

BWeidlich,



First of all, welcome to the TDR! The grids cycling on and off is completely normal, causing the volt gauge to go down to about 8 to 9 and then up to 12 to 14. I am in MN, and even with truck plugged in when extremely cold, grids will still cycle. On my 05, grids stop cycling at speeds of 20 MPH and above (computer controlled) regardless of time and air temp going into the intake. Like brista said, the grids cycling more then 15 minutes doesn't seem right. On my 92, no computer :-laf and grids stop cycling after engine is warmed up (usually takes 10 to 15 minutes before grids stop cycling on 92) Enjoy your new ride!



Paul

 

[Prairie Dog]

The grids can cycle even after the eng has completely warmed up, just depends on the outside temps.

It sounds like their working rite to me.

 

[RMachida]

If it is simply sitting idling, then 10-15 min is probably normal. I normally just wait about a minute before taking off and don't see them cycle once past 18-20 mph even at very cold temperatures.

 

[rbattelle]

Okay, some of you guys are talking about some behavior I've never heard of before. According to the powertrain diagnostics manual, and all my experience with my truck, the preheat cycle should never last more than 30 seconds and the postheat never more than 2 minutes 10 seconds.



As of 2003, heater grids should never, never, never cycle longer than 2 minutes 40 seconds (preheat + postheat).



I've also never heard of any 2nd or 1st gen guys running 15 or 20 minute grid cycles.



Did Cummins change the programming in 2005?



Ryan

 

[brista]

If they did they changed it back in 06 because my truck does not cycle the grid heaters for that length of time.

 

[RMachida]

I've never let it idle more than about a minute before taking off so I don't know how long it keeps cycling.

 

[bighammer]

I've never let it idle more than about a minute before taking off so I don't know how long it keeps cycling.

I'm with you, once started and running smothly with good oil pressure, away we go. It takes forever to get it to warm up just sitting. I get heat in less than 2 miles and can live that long without.

 

[Cattletrkr]

Even after being pugged in all night mine will cycle for the regualr 2. 5 mins and then quit cycling when the high idle kicks on. If it's really cold, the truck goes immediately to high idle, and I think it still cycles the heater. When it's -20*F the heaters really pull down on the engine.



10-15mins sounds really excessive though.