I bought a 1991 Civic DX a few weeks ago, in near mint condition, and I'm having two problems with this car, the defroster does not work, and the dimmer also does not work.

I did not operate the defroster since I bought the car, so I cannot verify if it had worked before, but the dimmer did work for about a week. All the wiring in the car is original, minus the installation of an aftermarket head unit. After the install there was one wire left, a RED/BLK wire, and according the every diagram I have, this is for the dim function in the factory head unit, and is grounded through the radio, so it will not affect the operation of the other lights. (Also verified by the clock wiring because it does not have a clock, but has the dimmer wiring ran for the clock, and the diagram shows this.)

The defroster switch has a bad indicator bulb, and when swapping bulbs from the hazard switch to check if it works, it still does not. The relay works, and the tracks on the back window look just fine, so it makes me think the switch is bad.

After I pulled the radio back out to make sure everything was still good, the wire I taped up shorted to ground, and blew fuse 8, so I replaced it. After that point the dimmer has not functioned, and jumping the dimmer does not change the brightness like it should, so this makes me think the dimmer is bad.

About a day earlier my charge light started acting stupid. It would not come on with the car off, but once the car is on, it lights up. When it does this I turn the car off, and restart it to see if it goes off, and it does. I don't think charging is a problem because I've driven it 1500+ miles without an issue.

Oil pressure light does not light up sometimes when the engine is off. More recently this has not been too big of an issue, but it does happen from time to time.


The car is 100% original equipment minus the radio. This cannot be as bad as it seems, this sounds like a shitty ground somewhere, but every ground I've seen thus far is just fine. Any relevant ideas are welcome. I will have better access to tools on Sunday.

 

Problems resolved, alternator voltage was dropping off gradually, just enough to put a very small charge on the battery. Was a reman, figures.

Dimmer control box under the dash shorted out. The RED/BLK wire shorted the base of the dimmer control transistor, killing the cluster and dimmer. The dimmer control wheel was fine.

Defroster timer circuit was faulty after replacing the bulbs, replaced.

So every component in this case needed to be replaced, just to make some use out of this post.