I hear a clicking noise from the back of the car. It happens when I press the brake pedal down. It happens when the motor is running or off. It is easier to hear when the motor is off. Is it a solenoid? If it is a solenoid, what is it doing? I have had the car for almost 20 years and never remember it happening.

I have the same click. But my brake lights don't work. Sound like a relay.

84 uses 2 relays for taillights.
1 for 1 bulb in each side so all 6 turn on w/ Brake, 3 on for turn left/right w/ 3 more if you push brakes.

Think is to keep OE turn/hazard flash cans and/or pedal switches happy.
later years drop this for several reasons so only 4 bulbs work as turn/brake.

Note that a lot of 84 wiring is 84 only and can't use/trust later electric diagrams.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

My 84 clicks. Always has.
No problems with the lights.