On the vehicles that have two separate (-) door triggers that are isolated from each other, most commonly found on newer GM vehicles, you will need to use two 1 amp blocking diodes for all doors to trigger the alarm.. One trigger is for the driver's door and the second is for the rest of the doors. If you were just to connect to one of these and not both, one or more doors of the vehicle would not be protected by the alarm. If you were to tie each of these together without the blocking diodes, some features of the vehicle will no longer function properly. Below is an example of connecting them to one alarm trigger.