Changing passenger headlight on 1993 Honda Accord sets off alarm?

Sounds like you need to look for a bad ground for the passenger headlight.

You should have a 10amp headlight fuse, and two 15amp fuses - one for each side low beam. And there is a relay for each low beam plus one for the high beams. The headlight switch provides the ground circuit.
The fuses and relays are in the fuse box in the engine compartment.
Check your owners manual for details.

Sounds to me like you need to reset the headlight housings... maybe they are vibrating very badly. ... OR, easy fix, get NEW headlight housings on EBay and install.

There are several things involved here. The combination switch (headlight,dimmer, turn signal switch), The headlamp relay and the dimmer relay. It could be a bad switch or a stuck relay.

do you have low or high beams?

LOW BEAMS: When headlight switch is turned on the headlight relay is energized providing voltage through fuse 37 and 38 to the headlights and the low beams come on.

HIGH BEAMS : same thing as above thru fuses 37 & 38. When the dimmer is in high, the dimmer relay provides ground to the high beams, and the high beams come on.

1. pull your flash see if lights come on?
2. check fuse 15 if good
3. check fuses 37 & 38.

some have separate fuses and/or relays for hi and low beam. If those are ok then it's probably in thew switch. good luck

you say you replaced both bulbs, you mean right and left or both the high beam and the low beam on left side?could be a bad ground for the left headlight. there should be some ground wires there near the headlight, LF corner under hood. without a wiring diagram here at home,I am not much help.

Check the earth wires have a good connection and are clean..

check the fuses under the hood or relays for ur headlights