Sounds like you need to adjust the brake light switch. It's under the dash near the brake pedal (oddly enough). It's usually a black or white cylinderical plastic object. The brake pedal lever will have a bracket that pushes against the switch when the pedal is in the up position which turns the light off. If the switch is out of adjustment, the bracket will either not contact the switch or it wont depress it enough to break the circuit.
it could be the brake light switch that usually contacts the break pedal when you depress the brake pedal. check that out first.
Typically, there's a hot switch attached to the pedal which closes the circuit to the brake lights (or to the CECU board in a truck which uses CAN BUS communication).
3rd brake light or rear brake lights?
Those tail lights could be the brake lights you are seeing and that would be a faulty brake light switch or the brake light switch is out of adjustment.
The brake lights in your 1983 Nissan pickup truck are controlled by the brake light relay switch. When the brake light relay switch malfunctions the brake lights will stop working.
Check fuses for brake lights. If your brake lights aren't workings the truck will not release the parking pin as it needs the signal from the brake switch on the pedal.
On a toyota tacoma 2003 SR5 when the tail lights are turned on the brake lights come on and when the tail lights are of the brake lights work just fine what could be the problem. If the truck has a trailer plug, inspect the plug and plug wiring for damage and corrosion.
Under the brake pedal is a brake light switch that when you press the pedal it hits it and makes your lights come on..sometimes when they get weak the pedal depresses them simply from the weight of the pedal and they stay on..Have a friend get inside the truck and pull UP on the brake pedal as you look at the lights..if the brake lights go off when they pull up on it..then it is that switch under the brake pedal
My 2000 Toyota Tundra Truck, the brake lights come on when your not pressing on the brake paddle. Not even even if the car is on.
Check fuse, check bulbs, check brake light switch, in that order.
Improper resistors.
Just connect it to one of the brake lights hot lead, and ground it to the truck.