Voltage fluxuates on start up 12v cummins
 

Hey guys I'm new to this forum and to diesels so take it easy on me please! I own a 1997 cummins 2500 4x4 with the long bed and I was wondering if seeing the voltage drop from 9 then back up to 14 was normal on start ups? Lights dim,blower slows idle drops a bit .Only seems to happen for the first 5 mins or so then it runs fine! Does this every time I start it. Just wanting to know if this is normal for a 12v cummins. Thanks in advance guys!!

it does it on mine as well. its been doing it since Ive owned the truck. i don't know exactly what it is but figure its something with the grid heater as they are very big amperage suckers.

Does yours do it in the summer too? I thought it could be the grid heater but notice it doing it when it is warm out as well. Thanks for the response!!

i will tell you when it gets warm. i cant remember. LOL

Both of my trucks do it when it's much colder than 50. I have a 12 and 24 valve. I believe it's the fuel preheater that causes this. As much as it's affecting yours I would have the alternator checked. I mean my blower slows a little but have never noticed the light or idle dim.

Yes it is the grid hearer ... if it does when its warm outside .. your intake temp sensor is faulty ... just to the right of the intake horn usually ..

otherwise what your experiencing it totally normal

I think if the temp outside is blow 65 degrees that's when it comes on.

Thats extremely useful info bro! Ill keep an eye on it when and if it ever warms up.. many thanks

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Thanks for the info man!!

its only supposed to come on @ 40* and lower ... the intake temp sensor could be failing ... :humm:

40 is to low its closer to 60