What exactly controls the shift up/down lights? I'm guessing its mainly the ECM, but does it get s ignal from the tranny?

The reason I'm asking is mine acts differently depending on whats going on. Usually when its cold out it doesn't come on till 2k rpm, and sometimes when its warm it comes on at 1200 rpm. I don't rely on it to shift, but it seems odd. I also recall a time when I was in neutral and it came on. That might be my neutral switch, but I doubt it. I've never seen it show downshift either. The light does come on when i first start the car (when all lights turn on)

This was borderline electronic, I hope this i the right section for this post

 

The shift light is for maximum fuel economy. If you went to the dragstrip and shifted according to that light your times would suck. Furthermore it doesnt ever tell you to downshift. I hope someone can anwser that question for you. My Z has that shift light but doent function because my car is an auto. Apperently they use the same guage cluster for stick/auto. I would like to figure out how to use that light on my car, but set it on how I like to drive.

 

Just get an aftermarket shift light. It will do the same thing, and you can program it for a preset RPM shift point. There are some now that are plug and play too. They plug into the cigarette lighter socket.

 

The shift light is controlled by the ECM. If you have PROM burning equipment you can change how the shift light functions

 

Ok, thanks

I don't really depend on it to shift, I just wondered why it acted like it does. Sometimes I really wonder how it thinks I'm going to go from 3rd gear at 1200 RPM into 4th gear and not bog out LOL

 

because if you did and the motor was fresh, the car would squeek out a extra MPG for the EPA rating...