drwsc6

I have a 2005 5.3L in my 74 GMC Jimmy with a T350 trans. I plan on using the Dakota Digital VHX cluster which can use the speed and tach signal from the 2005 PCM. I spoke with a rep from DD and he told me my computer would require a 120,000 ppm signal for this set up to work. I've read all over this board that the DD 8K sender units works for the vss signal to the pcm. Obviously 120K and 8K is a big difference. My question is, is the 8k sender just letting the PCM know the vehicle is moving but not giving an accurate speed, can't the PCM ppm value be changed? Thanks for any input.

S10xGN

iTrader: (11)

He could have also recommended their SGI-5 signal converter...

busta9876

iTrader: (3)

The PCM must be programmed to accept the 8K sensor. This means changing the constant for drive shaft pulses per revolution from 40 to about 3 to 3.5 depending on drive/driven speedo gears, axle ratio, tire size. After programming, the PCM will read the 8K sensor accurately. The PCM will also still output a 4000 pulse/mile signal for electronic speedometers. This works fine for letting the computer know vehicle speed, for use with idle control after deceleration, run emission readiness tests, and allow pcm to enter decel fuel cutoff, non of those things would ever happen with no speed signal to the computer.

Cruise control with drive by wire DOES NOT work correctly with the 8K sensor, seems the 8k signal is not high enough resolution and you end up with a pulsating feeling from the cruise control.

drwsc6

Thanks, that's exactly what I needed to know!