viper 5704 remote start

The reason it throws a code when that wire is not hooked up is because it provides 12V to the shift solenoids that are internal to the transmission. When the autostart fires up and the PCM does not see a 12v backfeed signal on the shift solenoid control wires it sets a myriad of codes for all of the shift solenoids and defaults to 2nd gear as the only forward gear. All the PCM does is ground each solenoid so if it cannot see 12volts backfeeding it thinks there is a shift solenoid circuit problem then goes into the above fail safe mode to allow the vehicle to be limped to a dealer for service.