Civic EG

A few day ago, I changed my brake prob valve of my 1992 Si sedan. After the job, I washed the firewall with water to remove brake fluid. Then I started my car and drove it for a couple of minutes to test the brakes. When I got back to the garage, I found out that the battery light is came on.

I took out the alternator and disassembled it. The brush holder was melted and the brushes were fixed in their place. I replaced it with a good one and mounted the alternator and tested it. The battery light is on again!

I took it out again and replaced the voltage regulator with an OEM new one. I tested the rectifier and it was bad, so I changed it with a good used one. I mounted the alternator and tested it again. Damn! The battery light comes on again!

I've tested the charging light circuit and it's OK. The grounds and battery mounts are OK. The belt is in a good condition and well tensioned.

So, what you think?

Thanks for your help!!!
I changed the alternator and the problem is not solved. The battery light is still on but when the engine revs more than about 2600rpm, it turns off. Under 2600rpm the voltage between battery terminals is about 12.2v and when the engine revs more than 2600rpm, the voltage drops to about 11.5v.
I cleaned and tested the battery cables and terminals. Everything was OK. I've tested the battery light circuit before and I'm sure that it's OK.
Now I think it's the ECU that doesn't operate properly. How can I test the ECU?

If you fried the alternator by running it when it was wet, I wonder if some of the other wiring in your charging system could be damaged/corroded from the short in the alternator. I have seen before that when there is a short, the copper inside the wired corrodes and the surface gets white and I'm sure that reduces the conductivity of the copper wire.

Also, since the battery light is on, have you had the battery tested to be sure it is good? Just to eliminate any possibilities.... Maybe it was damaged by the short. I thought the voltage was supposed to be closer to 14v but maybe I'm thinking of a different vehicle...

Thanks for your information
I've heard that some new OEM regulators are bad and it seems that mine is bad too!
I've checked the wires and terminals and charging system wiring. Now I think I have to change the regulator to see what happens.

Like teal said, have you tested the battery? Bring it to an auto parts store and get it tested and charged. After that, if you have a second vehicle, put that battery in there and see if it hits to more than 13 volts. The battery should jump from 12 volts to around 13-14volts when the car is on.

Well, if the alternator is functioning properly and the battery is bad, why the engine dies when I disconnect the positive battery terminal when the engine is running?

Like teal said try looking at your wiring as well. I had problems with a loose alt wire at the fuse box battery light would come after I hit a bump. Maybe you fried the wire. Which would not give a good connection.

Hello, I'm new. I just bought a 93 eg and it is having an electrical issue where the voltage will go up and down between 13 and 15.6 volts. ???????

Hi, welcome to the forum! After checking all the simple things like the wiring and connections, I would have the alternator & battery tested. Most auto parts stores will test these for free.