Tail light brake pattern

[DynamiteQC]

Both my friend have 91 type m while I have a 89 type m . I found out that both circle in each light light up when they brake but mine only have one of the two lighting up. Is this a difference between generation or the previous owner might just have put normal bulb? Could I wire something on the light modul to make them both work ?

[Skym]

There should be two bulbs on each side. Some remove inner bulbs on both sides for style reasons.

Also the bulb sockets sometimes are loose or bulbs blow. I had it blow 2x due to loose socket on drivers side. Could tap side of car and taillight bulb worked (cool party trick). Sometimes it didn't.

Open trunk and unclip clip on trim behind taillight on drivers or passenger side (or both) and open flap door. Then unclip plastic? light board on both sides and pull light board out and fit new bulbs. Then reverse procedure. Bulbs are like $1 or less each. Or fit LED bulbs, which is the latest trend on new cars (use less power, brighter).