M1079 Speedometer

[Bryteayes]

The speedometer in my 1998 M1079 usually does nothing, sometimes bounces up and down, and even more rarely appears to work. I have highway gears and EcoHubs and was going to replace the speedometer with a GPS speedometer instead of running down the errors and resetting the dip switches. And then I discovered that the speedometer is connected to the WTEC III, CTIS, and possibly the chain gun. Will disconnecting the speedometer trash any of the other systems?

 

[Ronmar]

Well its connected to the TCU because thats where the speed signal comes from(output speed sensor down in the transfer case). The signal also feeds the CTIS controller that counts pulses to trigger its overspeed response. Since you have more than halved the pulses from the trans at any given speed, the CTIS overspeed response should never happen ever again, unless you are in the habit of passing thru the speed of sound in a 1079… You would have to reprogram the CTIS controller to restore this functionality…
you should be fine to proceed to A GPS speedo…

 

[Bryteayes]

Well its connected to the TCU because thats where the speed signal comes from(output speed sensor down in the transfer case). The signal also feeds the CTIS controller that counts pulses to trigger its overspeed response. Since you have more than halved the pulses from the trans at any given speed, the CTIS overspeed response should never happen ever again, unless you are in the habit of passing thru the speed of sound in a 1079… You would have to reprogram the CTIS controller to restore this functionality…
you should be fine to proceed to A GPS speedo…

Thank you