70 LS1

iTrader: (1)

I am finally getting around to installing a working speedometer in my car. I picked up a Classic Instruments speedo that works off of 8000 pulses per mile.

I am pretty sure the T56 VSS operates at 4000 pulses per mile.

What is the VSS ouput from the PCM (C2 pin 50) I know it is a square wave, but how many PPM? Thats the signal I plan on using.

Thanks.

G-Body

iTrader: (4)

The PCM puts out a 4000 pulse per mile signal. I thought there was some way to change the PPM output, but when I just checked HPTuners I can`t find it

jannes_z-28

Well you can trick it by putting in other values for your rearwheel diameter and rear axle gears. The 4000 pulses per mile is calculated from the these values. So if your speedo only works with 8000 ppm then you have to change your PCM setup so that it thinks the vehicle runs twice as fast as it really does.

Usually there are DIP-switches to change the setting on the Speedo.


Jan

70 LS1

iTrader: (1)

There are DIP switches, and a calibration chart that came with the speedo. I'm not sure it will let me adjust all the way down to 4000. I'll try it out and see what happens.

Is there a way to change the PCM output?