How long should truck cylce?

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In cold weather say around 25 degrees F. How old should the "wait to start" light stay on? After the light goes off is it safe to start the truck. Does this mean that the grid heater is through cycling? Thank You


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1995 4X4 2500 5 speed, turbo scilencer ring gone, chrome nerf bars, CB, Sony CD, Kenwood EQ, Tinted windows, Tool Box, Diamond plate bed caps and tail gate.
NRA Member!!!

 

[Archive]

The wait to start light should be about 15 to 25 seconds. Sometimes people cycle the heater twice, mine always fires up after the first cycle no problem, but so far its only been about 8° for the low. After you start the truck the heaters will continue to cycle on their own. You can verify this by watching your voltage dip, as well as your headlights dimming from time to time while sitting there at idle. If you read the owners manual it will list some conditions which will shut the heater cycle off, such as exceeding a particular speed, which on my 2001 its 18 mph and the post heater cycle will shut off. If the engine is started before the "Wait to Start" light goes off, the preheat cycle will turn off. If the engine is cranked more then 10 seconds the post heat cycle will turn off.

Hope this helps explain it some.

 

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Caleb,also from the '95 service manual,heater on time before starting 15°-59°F=10 seconds;0°-15°=15 sec ; below 0°=30 sec. When the light goes out it is ready to start,the heaters will turn off during cranking. After the engine starts the post heat engine running cycle will start for up to 3 1/2 minutes,it will stop cycling if ;intake temp is over 59°,the starter is operated again,the engine stalls or the vehicle speed is above 10 mph.

I've never cycled mine more than once before starting,it always has started. Sometimes it will run rough for a few seconds. Looks like from the above numbers that the intake temp sensor determines how long the grid heater needs to be on before starting according to the temp,no need to cycle twice. While the manual is on the same page,here's what it says about the block heater;Must be plugged in for at least one hour to have any effect,above 40°F =not required,40°-0°F=suggested,below 0°F=required. When I plug my '95s in the grid heaters have never come on at all down to minus 25°.

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95' 25004X4,AT,Driftwood,Banks Stinger,Warn fender flairs and running boards(Play truck)95 3500,5 speed,Driftwood,Banks&Phscotty,34,000 GCVW apple and tractor hauler(work truck)

 

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On my 96,unless it was below 20 degrees out,I never even bothered to wait,it fired immediatley anyway,and as soon as it starts it will start to cycle anyway. Below 20,i let it stomp its feet and rub its hands together for about 20 seconds. AS long as speeds are blow 18mph,it it will cycle as long as air intake trmp is below 59 degrees,measured at the intake on the engine by the temp sensor. This pre-heater is a Dodge spec only,it isnt needed by the Cummins,thats why i dont wait for it,unless its real cold. It just helps it warm up quicker and run smoother cold.