I'm trying to get my autometer gauges hooked up and the speedo is the last thing. I have an ls3 with e67 ecm and 4L70E transmission. Autometer designer series 2 speedo.

It works with the speed input from the ecm but reads about half the correct speed. Is this something that can solved by a tuner (I'm getting it dyno tuned Wednesday) or do I need to find another way?

I've read from past threads (different ecm used though) that I can find the vss output from the transmission (input to the ecm or tcm) and jumper off of it to the gauge for a signal input to the speedo.

Thanks fellas....yall are always helpful.

 

Isn't there a way to calibrate the speedometer? My old automated speedo you could set it to what ever you wanted.

 

I've used Auto Meter speedos on all my LS swaps. Typically Sport Comp Two's. To get them to read as they should you need to calibrate them. I don't have the instructions in front of me but the calibration is done by driving a certain distance. Go the Auto Meter web site for details.
Depending on your harness it should have a wire that goes from the ECM to the speedo since it's an auto. On my current L92 swap there is a wire from the ECM to the speedo.
I can't confirm but from what I've read splicing into the vss wire can weaken the signal to the ecm and cause shifting issues.