I had my borther install an old Viper 550 ESP remote start that he had from his old truck. Mine is a 05 Avalanche. Everything works fine as it should, alram, start, etc...But now the tach in the truck is pulsing like there is an extra voltage surge. I verified through a multimter that it was hooked to the right wire (4 volts AC). Violet/ white wire out of viper brain.
I think it may be the tach wire that is coming out of the door lock module? Any help or thoughts will be appreciated.
Tach basically is jumping from 1500 at idle to sporadicly up to 2500, then to 1500 then to 170 and so on....Continues to flicker while driving as well.