5900 remote start

hi, i have a 00  gmc sierra and i installed the viper 5900 and the dei 555L, when i go to remote start it, it'll engage the start but it want stay engage long enough. some times it'll be just long enough so it'll run on the first try but after that it want crank anymore??? i'll learned the tach three times and the light stayed solid each time example: it's like you getting in your car and turning you key to start but you don't leave the key in the start position  long enough so it'll crank. any info is welcome and needed thank you for reading

During remote start attempts, is the security light on the dashboard flashing, or does it come on steady and then go out? If it's flashing, the Passlock bypass isn't correct. Also, temporarily, go into programming and change two features: Change from Tach Sensing to Voltage Sensing Change crank time from 0.6 seconds to 1.0 seconds Try remote start again. If that made it work, then you had the wrong tach wire. If it still doesn't work, your tach wire was probably good.

change the it from tach to voltage sense and it worked fine, so i guess i have the wrong tach wire, any suggestions where to fine another tach wire? thanks for all your help