Okay....
Power for the brake lights comes from the headlamp switch (believe it or not) then proceeds to the stop lamp switch on the brake pedal, then up the steering column to the turn signal switch, back down the column and out through the left kick panel, through a channel under the driver's door sill plate and up the left side of the car into the trunk.
Power for the turn signals comes by way of the ignition switch to the turn signal flasher then up the steering column to the turn signal switch. When leaving the turn signal switch it uses the same "output" as the brake lights as they use the same filament in the rear bulbs for both brake lights and turn signals (the turn signal switch actually "interrupts" the brake lights when the switch is selected for a particular side).
Typically, when you have NEITHER stop lights NOR turn signals the problem can be traced back to the turn signal switch, the wires leading from it back to the rear of the car, the lamp sockets or bulbs, or grounds.
The first place to check is for power at the stop light switch. Disconnect the plug and using a test light probe the pins in the plug. One should have 12V. The other should have nothing. If you don't have any power at either pin you need to trace the wire back to the headlight switch but I doubt you'll find that to be the issue.
The next place to check is for power at the turn signal flasher. Disconnect the plug and check the pins of the plug for power. Again, one should have 12V and the other nothing. If you don't have power at either pin you need to trace the wire back to the splice with the ignition switch "A" circuit. Again, I don't suspect the problem to be there, either.
Next, examine the connector for the steering column harness to make sure it's secure. You can use a small cotter pin or unbent paper clip and your test light to "backprobe", that is to slip the "tool" into the connector from the side where the wires enter the plug so you can check for power while leaving the connector sides plugged into each other. The brake lights should be the solid GREEN wire in the connector. The turn signals should be the solid BLUE wire. The GREEN wire should have power whenever you depress the brake pedal. To isolate the switch, use another small cotter pin, etc., as a jumper to connect the pins in the stop light switch plug. This should provide constant power to the GREEN wire regardless of whether the pedal is depressed or not. If you had power at the stop light switch in the initial test, have jumpered the stop light switch plug, and DON'T have power to the GREEN wire at the steering column harness connector then you have a wiring issue between the stop light switch and the steering column harness connector.
Now, turn the ignition switch to the "ACCY" position. You can also use the "ON" position, but if you DO so, disconnect the RED/GRN wire at the ignition coil+ to avoid damaging the ignition system. With the key "ON", "backprobe" the BLUE wire in the steering column harness connector. You should have power. Depending on the resistance in your test light or the type of flasher being used the power could be constant, or it could flash, like a turn signal. If you don't have power there then, again, you have a wiring issue between the steering column harness connector and the flasher, provided you had power to the flasher in the earlier test.
Okay. Assuming you had power in all these previous tests, now "backprobe" the GRN/ONG and ONG/BLU wires in the steering column harness connector with the stop light switch either jumpered or connected and the brake pedal depressed. If you have power there, but no brake lights, you have a problem in the wiring, sockets or bulbs between the steering column harness connector and the rear of the car. If you don't have any power there you have a problem with the turn signal switch or the wiring up the steering column.
Same thing with the turn signals....with the key in "ACCY" or "ON" as above, "backprobing" the GRN/ONG and ONG/BLU wires in the steering column harness connector while selecting the left and right turn signals you should have power, either solid or flashing, depending on the state of resistance in the circuit. If you have power then the problem is between the steering column harness connector and the rear of the car. If you don't have power the problem is with the turn signal switch or the wiring up the steering column.
Lastly, the dash lights. First, pull the headlamp switch out to the first notch. Rotate the knob all the way in both directions and observe the gauge lights. If you don't have any lights by turning the knob inspect the 2-1/2 amp fuse (the little one in the fuse box) using your test light by probing EACH end of the fuse. With the light switch pulled out one (or two) notches, BOTH ends of the fuse should have power. Again, rotate the headlamp switch knob in both directions to see if you get power. If only one end has power the fuse is no good. If both ends have power and you still have no dash lights you have a wiring problem to the lamps, the bulbs are all blown or the instrument cluster is not properly grounded. There is a ground wire from the cluster to the metal dash frame. If you don't have power to EITHER side of the fuse then you have a problem in the wiring between the fuse box and the headlamp switch.
Hope this helps!
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