1985 Nissan pickup- All headlights test good. On

check your headlight fuses and relays as well as the switch on the column. you might have to replace the switch for them to work. Also, see if they come on when using the flash feature of the headlights.

I wouls check the fuses first. They are located inside the car in the panel with the other fuses and the cover should tell you which fuses they are. There is a bank of relays next to the battery which relate to the headlights, retract relays, a passing relay and a headlight relay. If the fuses are good and the headlights pop up, but do not turn on, you might have a bad head lamp relay. The relay at the very front as you face the engine compartment is tha headlight relay. The second relay is the passing relay. They are both the same color, black. You should be able to swap them out. If the lights come on, then you know the relay was bad, you can only buy them at a Nissan dealer. If ththey didn't, you may have a bad head lamp switch. In not being a professional, you wouldn't know how to bypass the switch to confirm it is bad, but if you have done properly what I have instructed you yo do, chances are the switch is bad. Note: in checking the fuses, using a test light is usually the best and fastest way to confirm that the fuse is good or bad by touching the tip of the test lead to one side of the sxposed metal on the fuse and then on the other side. The light should go onwhen you do this test. If it doesn't light up on one side, the fuse is blown. Make sure you have a good ground on the other end of the test lead. Often just clipping the end of the lead to the ignition ke while it is inserted in the ignition lock will work. Make sure that the key is turned all the way on to where the dash lights are lit even though the head lampe are not on the switrched circuit, you never know what you will find sometimes.

Try checking with the lights on. There's also a fuse link on the positive battery cable.

Did you check ground strap between Eng. block and ext. fire wall ?

Check the headlight relays

Had this once...Check voltage at plug on dim side to see if you have power.
If so, check continuity thru head light.
(I had both headlight low beams burn out at the same time once.)
Ya might check your headlight relays are seated for good connection as well.

you have a bad ground wire to it

first i would want to know that all the headlamps are in good working order. it kind of sounds like these are also bad bulbs. you will also need to look for good ground wires just behind the headlamp assemblies. to answere your question, YES. if things were not repaired properly and without attention to detail then you could have wiring issues. on the plus side it doesnt sound too difficult. try these items first.

check the fuses first then if they are ok check the relays under the bonnet hope this helps regards Jim

check to make sure that both lamps aren't burnt out-halogens like to do that.