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Discussion Starter · #1 ·
When i bought my truck the engine heater light never came on for 3 month then in the winter months when cold would come on like it should . Now it's warm and the light always comes on at what temp should it not be comeing on ?
 

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thats how mine is some times it woldnt even come on in the coldest mornings i was wondering the same thing
 

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are you guys talking about the glow plugs/wait to star light, if so it should only come on when i think its below 50 degrees. Then you have two other heaters the engine block heater, which only comes on when you plug it in and the grid heater which allows warm air to enter the intake manifold thus warming the engine sooner. The only way you can tell if its on is you can watch your lights dim and you voltmeter will drop and raise. Hope this helps you all out.
 

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Discussion Starter · #4 ·
yeah glow plug light thing ... it warm out and still on
 

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are you guys talking about the glow plugs/wait to star light, if so it should only come on when i think its below 50 degrees. Then you have two other heaters the engine block heater, which only comes on when you plug it in and the grid heater which allows warm air to enter the intake manifold thus warming the engine sooner. The only way you can tell if its on is you can watch your lights dim and you voltmeter will drop and raise. Hope this helps you all out.
Your truck has no glow plugs, just a grid heater, a/c block heater and a heater in the filter housing. My grid heater will still come on when its in the low 60's. you can hold the odometer (trip meter) reset button in and turn key on for a light test.
 

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When you turn the key on, the IAT sensor reads the temp, if below 55F, the heater grid will cycle. On mine, you can hear it; kind of sounds like a capacitor charging up. In warm weather, the IAT sensor still takes a few seconds to read and tell the PCM it's ready to start and turn the light out. On my 98, it will crank with the light on. I don't usually do it. It is such a habit to wait. I sometimes turn the key on in a rental car and "Wait to Start" :lol3:
 

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I normaly dont pay too much attention to that light. . .yea, it will come on when it is 50-55. . .but if she's been in the sun I'll go ahead and fire her up. 50-55 in the mornring, yea I'll let it cycle.

been thinking about getting one of those fancy grid heater elimination things since it doesnt get that cold here in HotLanta
 

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When Engine Manifold Air Temperature is below 66*F the light will remain on indicating the Intake Heating system is active.

We get temps below freezing through the night then it warms up to 70 by mid-morning ... but the grid heater still comes on cuz the manifold temps haven't had time to warm up to the actual air temp yet. It's not based on outside air temp.
 

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Mopard hit the nail on the head. If the IAT sensor is still cold from an overnight cold soak even though the air has warmed up it will still activate the grid heater. By the same token through the mild winters here in SC the grid heater may work first start of the day, but later starts usually don't cause a wait to start light because the engine holds enough heat while sitting after being run.
 
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