SHIFT UP Light on dash

[ouray19]

I have a 95 k1500, 350, TBI, 5-speed manual and the "shift up" light on the dash keeps coming on erratically. I have read other posts that say this light should come on when you get high rpm's. Mine has been coming on in 1st-4th gear at about 1500-2000 rpms. Is that normal?
Wondering where the signal comes from that tells this light to come on. Is it related to rpm's, speed? Is the sensor that activates this light come from a vacuum or is it electronic?
I know, lots of questions, but just curious because it does not seem right for it to come on under low rpms. Any input or comments are welcome.

 

[RichLo]

Intake Manifold Vacuum triggers that light.

 

[ouray19]

Thanks RichLo. I am also getting an occasional code 44 and was wondering if the intake manifold gasket may need replacing.

 

[RichLo]

that could very well be the case. I would also check over all your vacuum lines before taking the manifold off.

 

[ouray19]

Do you think the fuel pump could have anything to do with the shift light or code 44?

 

[KrpticKyler]

Did you ever figure out what the problem was that was causing this?? my truck is doing the same exact thing

 

[5spd Z71]

Also depends on speed and throttle. If I'm driving easy down city streets, it'll come on between 1500-2000 rpm. If you step into it more, the light should disappear.



Sent from my iPhone

 

[jkeaton]

Did you ever figure out what the problem was that was causing this?? my truck is doing the same exact thing

Look at the vacuum lines as was suggested.