99 blazer remote start problems

Make sure that you have interfaced the passlock security system on the vehicle - from the sounds of it, this is what your problem is - Here is all the vehicle info you should need to check what you've done

|       ITEM      |     WIRE COLOR     |POL|       WIRE LOCATION        |

|              12V|red                 |+  |ignition harness            ||          STARTER|yellow              |+  |ignition harness            ||         IGNITION|pink                |+  |ignition harness            ||  SECOND IGNITION|white               |+  |ignition harness            ||        ACCESSORY|orange              |+  |ignition harness            ||       POWER LOCK|lt. blue            |+  |brown plug at BCM *1        ||     POWER UNLOCK|white               |+  |brown plug at BCM *1        ||       LOCK MOTOR|gray                |   |drivers kick panel          ||     UNLOCK MOTOR|tan                 |   |drivers kick panel          ||    DISARM DEFEAT|tan                 |   |passengers kick panel       || PARKING LIGHTS +|brown               |   |lt. blue plug at BCM *1     || PARKING LIGHTS -|white *4            |   |lt. blue plug at BCM *1     ||       HEADLIGHTS|PURPLE / white        |-  |purple plug at BCM *1       ||     DOOR TRIGGER|*2                  |-  |BCM *1                      || DOME SUPERVISION|use door trigger    |   |                            ||  TRUNK/HATCH PIN|pink/black          |-  |lt. blue plug at BCM *1     ||TRNK/HTCH RELEASE|black               |-  |purple plug at BCM *1       ||FCTRY ALRM DISARM|lt.green            |-  |purple plug at BCM *1       ||       TACHOMETER|white               |   |PCM *3                      ||       BRAKE WIRE|white               |+  |steering column             ||     HORN TRIGGER|black               |-  |steering column *5          |

Notes:

NOTE: This vehicle has the passlock II immobilizer system that, when adding a remote start, must be interfaced with. Use DEI part 555t or 555L.  *1 The BCM is located to the right of the accelerator pedal below the radio.  The plugs on the BCM face towards the drivers side.   *2 Use tan for the drivers door located in pin B4 of the purple plug, orange for the passenger door located in pin B2 of the purple plug, and dk. blue/white for the rear doors and rear hatch located in pin B11 of the lt. blue plug, must diode isolate these wires.  *3 The PCM is located on the passenger fender. On the 2.2L the wire is in a black 80 pin plug pin 10, and on the 4.3L the wire is in a red 32 pin plug pin 20.  *4 This wire will not test when using the headlight switch. This wire is triggered by the DRL system. To meter the wire, start the car with the parking brake set, when the brake is released this wire will go to ground.  *5 Also found in the brown plug at the BCM on vehicles with a factory alarm.