Only solid black wires for lights will be at the light bulbs themselves, they would be the Ground wires

Dash lights use Light Blue/red stripe wire, it comes from DIMMER on light switch, it splits to power ashtray light and radio light, also heater control light

There are two flashers, one for the turn signals and one for the 4-way

Do 4-way(hazard) lights work?

 

 

 

Your turn signal problem is its flasher or fuse, so test for voltage at the fuse with key on, also see if Reverse lights work, backup lights usually share the turn signal fuse, so if both don't work then that fuse is bad or not getting 12volts with key on

The 4-way flasher has its own fuse and flasher, but uses the turn signal wiring from the turn signal stalk out to the lights, including dash lights, so all that wiring is good if they work.
4-way has 12volts all the time, not key on only power

Problem is, 12volts is not getting to the turn signal stalk for turn signal use when key is on

Battery(12volt)--------ignition switch------------fuse------flasher----------turn signal stalk-------turn signal bulbs

I have never seen it happen but................the Hazard switch(4-way switch) passes the turn signal voltage thru to turn signal stalk, so when you press down the Hazard switch it cuts off turn signal voltage to pass on its own voltage
Not sure on 1989 though

A thermal flasher works by having 12v and then being connected to a LOAD, like light bulbs, the load of the lights causes the flasher to heat up and the bi-metal bar inside bends, cutting off the 12volts, with no Load it cools down and straightens, reconnecting the 12v and lights come on again, this heat up/cool down repeats until load is removed, turn signals turned off.
This heat up/cool down is also why when you hook up a trailer the turn signal may flash faster, more Load, with the added trailer lights
And also why turn signals won't flash if a bulb is burned out, not enough of a load to heat up the flasher, same thing can happen with LED bulbs, they have less Load than regular bulbs, so flasher doesn't heat up

 

 

 

The turn signal fuse is not getting 12volts when key is on

Do you know which fuse is for turn signals/backup lights?
Should be 15amp

Pull it and use test light or volt meter to see if it has 12v with key on

Found this for that wire color, 1983-1989
Light Blue With Red Stripe Wire - From Light Switch To Dash Lights

 

 

 

Good work, but thats odd

Front turn signal bulbs use separate ground that rear turn signal bulbs, and the dash indicators also have their own ground