I need help getting an rpm signal for my TCu Ive tried coil # 1-2-3 not exact reading as the speedo it gives 80 rpm at idle It must be 600 so please help me with this TCI and Fast couldnt help me they said they dont have any solutions for me.

Car is 08 silverado 5.3

 

i got my signal from behing my gauge cluster. i dunno if urs is the same but it was a white wire.

 

i got mine from the cluster also

 

No the 07+ models have a lan system not like the old models but Im gonna try opening mine today and Double check

 

I don't understand, why wouldn't the coil be accurate? That's the same thing they use on the dyno

 

dont know got the wire description it says the white wire on the coil ignition and there is no white wire there.