Voltage test points and expected voltage readings for first-gens.
(I verified to apply to 1986 to 1988 22R-Eliable, based my own 1986 and pdf schematic of 1988).

This will determine if your wiring and power are good. If wiring and power are good, suspect your bulbs.
Other tests may be needed but these points will cover most troubleshooting scenarios.

Headlight relay and fuses are in fuse block in the engine compartment.




Multi-meter in Volts DC mode (usually 20-V range IF not auto-ranging). Negative (black) probe on bare, shiny metal of negative battery post or bare, shiny metal of body ground.
probe points A through H in Off, Low-beam, and High-beam modes.
Points E,F,G and H are on the H4 connector. Probe the back of the pins or Pull terminal out slightly to be able to probe the contact blades while lights are still operational.

EXPECT READINGS BELOW FOR NORMALLY-FUNCTIONING LIGHTS. For any deviation, let us know.




H4 CONNECTOR PIN-OUTS (FEMALE SIDE ON HARNESS)


ALTERNATIVE METHOD OF VOLTAGE CHECK (across pins of the H4 connector):

LOW-BEAM

HIGH-BEAM

HOW HEADLIGHT SYSTEM WORKS.
(Schematic below)



When headlight switch is turned on, headlight relay in (engine compartment fuse block for first-gens 22RE) energizes, closes contact, sends +12V to both headlight fuses and to pin 3 of both bulbs.

Toyota uses switched-ground control; Dimmer-switch select which filament (high or low) of bulb to connect to ground.
When in low beam position, switch contact 6 (HL) of dimmer-combo switch connects pin1 (red with green stripes) to ground (G = zero volt, H is floating so there is 12Volt there.)

When in high-beam position, switch contact 5(FU) connects pin 2 (red with yellow stripe) of bulbs to ground (H = zero volt, G is floating so there will be 12V there. G is also connected to high-beam indicator so that 12V will turn it on.)