Service Engine Light On When I Turn Key

[Kirkathon25]

what does my service engine light mean when its on when i turn the key but shuts off when its running, and there are no codes, i have a message center in my truck so its not like time to change the oil or anything, just wondering if anybody knows

[jwhjr]

Normal startup diagnostics.

[Kirkathon25]

it never did it before tho, could it be because it has codes in the history of the computer?

[8.1HD/ALLISON]

Every vehicle should light all dash lights up at key on to check bulb operation. Check engine light should stay on if only have key on engine off, once you start up it should go out. History codes would show up when checking codes.

[Kirkathon25]

yeah it stays on when the key is turned to on position, its probably something stupid like my oil change light where you have to push the gas pedal three times to make it go away

[8.1HD/ALLISON]

No there is no reset. I am telling you that the check engine light comes on with the key on engine off as a bulb check. They all do it. It is normal.

[Kirkathon25]

o ok, well it just never did it before so thats why im confused, but if theres no codes i guess its nothing to worry about its just irritating, yeah i know the bulb check but when all the other lights turn on they turn off after but that light will stay on.

[Matt_]

If your key is on and the engine is off, the check engine light should be lit.

 

If its not lit... then you have an issue

[Truckin2003]

I agree. Its completely normal for it to stay lit when the ignition is on, and then go out when you start the vehicle. Thats how it should operate.

[hockeypro1411]

The battery light should be on too, if I remember right.

[FarmerDave]

If the check engine light comes on with the key on run, but engine off, it means your alternator is OK. That's all there is to it. If i remember correctly (college was a while ago) when one of the windings in the alternator has failed the light will not come on.

[revrnd]

Usually when you start any vehicle all of the "idiot" lights will come on so you know the light/lamp/indicator is working. If you don't see it come on, then you should have that particular system checked.