1993 Pontiac Trans Am 5.7 autowhile the headlights and parking lights are off, there isn‘t a hint of a problem, but once the parking lights is on or the headlights, the left turn indicator does not work nor does the rear brake lights, the third brake light does work, side note- a viper security system is installed but the wiring harness is disconnected
you have a bad ground connection for the T/S, the grounds are usually located near the light sockets, but you should get a wiring diagram to find them.
You didn't say whether everything was okay or not before disconnecting the security alarm system, but it sounds to me like a short in your electrical system that may have something to do with your lights (not the alarm system). It could be caused by a wire rubbing against the body somewhere and shorting out against that.
It's the alarm not being hooked up. If you don't want it connected, you will have to track down where it is tied in with the park lights and disconnect it there and reconnect the wires. They probably wired it through the grounds and without it connected is giving you all sorts of faults.
