Chevrolet Repair: 2005 1/2 ton p/u, key cylinder, purple wire

Question
i replaced key cylinder lock but i still have intermittent starting what else can i check?

Answer
HI JOHN, SO YOU ARE SAYING THAT THE ENGINE WILL START AND RUN,SOMETIMES...WHEN THIS ENG DOES NOT START,,DOES IT CRANK OVER LIKE THE STARTER IS ENGAGING BUT THE ENG IS NOT RUNNING ??? OR I WILL GUESS WHAT IS GOING ON AND THAT IS, YOU TURN THE KEY TO CRANK MODE AND NOTHING HAPPENS. I BET THIS IS IT ??? OK I WILL GO WITH THIS,WHEN THIS HAPPENS YOU NEED 2 PEOPLE, ONE TO TURN THE ING KEY TO CRANK WHILE THE OTHER PERSON IS UNDER THE TRUCK BY THE STARTER WITH A TEST LIGHT OR A VOLT METER CHECKING FOR POWER [12 VOLTS] ON THE SMALL WIRE NEXT TO THE BIG POSITVE BATTERY CABLE. I THINK THIS IS A PURPLE WIRE ON THIS YEAR TRUCK..IF THERE IS POWER [12 VOLTS] TO THIS WIRE AND NO STARTER ENGAGMENT WHILE THE KEY IS IN THE CRANK MODE THE STARTER IS BAD..REPLACE IT. ALSO JUST MAKE SURE YOU HAVE GOOD BATTERY SUPPLY POWER [12 VOLTS] ON THE BIG CABLE TO THE SARTER SOLENOID AS WELL..MAKE SURE ALL THE CONNECTIONS AT THE STARTER AND BATTERY POST ARE CLEAN AND TIGHT..IF NO POWER TO THIS POINT THEN YOU MAY HAVE A BAD IGNITION SWITCH OR BAD NEUTRAL SAFTY SWITCH..SEE IF IT WILL CRANNK OVER IN NEUTRAL,IF SO THE SAFTY SWITCH IS BAD..LET ME KNOW IF YOU NEED MORE INFO OR IF I DID NOT FULLY ADDRESS YOUR QUESTION..GOOD LUCK TO YOU,,,,TOM