Headlights are dim despite being new

[Regan-RK]

I recently did the h4 swap for the sealed projectors i just got plastic light housings and put the h4 bulb in it and the lights are spotty at best some nights they work somewhat and some nights they are extremely dim i replaced the alternator already which did fix alot of other issues but not the headlights
yes i have checked the fuses
i have a 1987 liftback

[ShiRen]

So were they brighter with the sealed beams?

[Regan-RK]

I bought the car with only one working sealed beam so im not sure if it wouldve been brighter but that one that did work wasnt very good

[Oldblueaccord]

I recently did the h4 swap for the sealed projectors i just got plastic light housings and put the h4 bulb in it and the lights are spotty at best some nights they work somewhat and some nights they are extremely dim i replaced the alternator already which did fix alot of other issues but not the headlights
yes i have checked the fuses
i have a 1987 liftback

Those H4 bulbs, unless its some kind of LED, pulls alot more power and as you said in your other post the combo switch will melt with regular H6054 (edit) bulbs if your wiring has gotten bad.

I'd look in putting regular sealed beams in it or equivalent LED which pull alot less amps.

Voltage readings and amp readings would tell you the real story.

[ShiRen]

That and you said you had problems with the ignition switch wiring... well the multifunction switch, which all of the headlight current goes through, often has issues with its plug on the column, and internally on the switch contacts. Current is very, very unkind to the headlight circuit

[fortekosakku]

Fully charge the battery with a trickle charge and reinstall and immediatly turn on high beams without cranking the car. If its bright as F. Your bulbs are fine. Your wiring is fine. If not, the bulbs are probably bad or you got a parasitic drain or short.

If bulbs are nice and bright with a full and FRESH battery charge then lets look at a simple alternator load test. You will crank the car , turn on high beams, the AC, the radio, all the interior lights and any other electrical load on the battery you can think of, from the sound system you may have to the heated seats if you have them. All loads. While that is going, pull out a multimeter and measure DC voltage between the battery terminals. With all that crap on, you need to be AT LEAST 12.8V You SHOULD be 13.5 to 14V if the alternator is able to keep up with all the loads and provide a full recharge. If you have a full load and are at 12.8V then you are barely hanging on and may or may NOT be draining the battery on long night runs in the rain. If you are running below 12V under full load than you need an upgraded alternator with higher amps or you need to remove a load from the circuit or the alternator is starting to burn out and it needs replacing. Bass cabinet in the back ? Running an Amp? Fog lights? Any other electrical load not from factory that isnt plugged into a cigerette lighter? All those things matter to old cars.

If you do show any of your testing of the battery , under load, to be under 12v. Then switch testing points.....put the red positive lead of your meter to the OUTPUT bolt and wire coming from the alternator that feeds the battery and put the black negative lead of your meter to the negative battery terminal. If you show 14V or 13V there....but 11V between battery terminals....then you are losing voltage along the battery cable wires themselves. Usually the battery cables that connect to the terminals have gone bad in this case or come loose or developed that green corrosion crap inside the protective plastic casing that covers the copper wire of the battery cables. If you show anything under 13V coming from the output bolt of the alternator, then the alternator is getting weak and dying.

[ShiRen]

The headlight switch has a lot more potential for voltage drop than the alternator, they didn't put a headlight relay in it, so full current is going through tiny switches. If your charging system has a voltage drop then you are going to have problems with everything else electrical, especially starting.

[Dr_Snooz]

So OP should do a combo switch rebuild listed in the How-To section.

[carotman]

So OP should do a combo switch rebuild listed in the How-To section.

Indeed!

These cars don't use headlight relays and the full current from the headlights goes to the switch. It can corrode after a "ahem" few years.

[ShiRen]

Indeed!

These cars don't use headlight relays and the full current from the headlights goes to the switch. It can corrode after a "ahem" few years.

Forget corrosion, I don't know how they have managed to not catch on fire after all these years