When I tried to open the back doors, with the remote or the door button. You could hear a click in the rear passenger fender well.
You would think GM would have a way to replace the instrument cluster and program it to the car.
Monday I think I'll talk to the parts department guy and see if has any info.

 

I did find a wiring diagram that shows the panel rear door relay is controlled by the instrument cluster.

 

Well Lucky, as Ricky said to Lucy, "that sure 'splains it".

Good find!

 

Show that to the service writer and watch for the glazed eyes!! And please let us know what and how much smoke they try and blow up your skirt!

 

Even a blind squirrel finds a nut once and awhile.

 

GM shops No can do, Speedometer repair shop Don't know if they can do this.
So I talked to a person down the street that tinkers on his chevy and has a 200mph speedometer in it.
After he stopped laughing. He tolled me to get a 140mph overlay. Then get a Hypertech speedometer recal tool for $226.
The speedometer will be right on but, your trip meters, gas milage figures, shift points,and odometer will read low miles.

Think I have dug a deep enough hole on this one.

 

Let's call it , a day and sell off the spare parts! Great that you tried!! Myth Busted!

 

This is the way to have the 140 speedometer with a stock LS or LT cluster.