I own a 93 Del Sol Si a/t and I'll try to be as descriptive as possible with what is going on.

The car will start and run but the charging system is not working properly. Both the alternator and battery checked out as working properly by themselves. When the car is running with no accessories on, there is a constant drain on the battery at idle. Maybe a hundredth of a volt a second.

I went thru the steps in the manual I have (Haynes) and these checks have all passed:
Drivebelt, alt. bolts, all fuses, no shorts found (used test light with battery neg. to ground), no noises from alt, charging warning light is ok, cleaned all corrosion on battery, replaced (trans, battery, water pump) grounds with 4g wire (old ones were in questionable condition), continuity of black/yellow and white/blue wires from alt. (showed battery voltage with key on the II position), continuity of white/yellow and blue alt. wires with test light to the ecu (pin a16 and d9).

The only other parts of the system i can think to be a problem are the alt. wire harness (cleaned visible corrosion but very hard to see into and clean) or the ecu its self.

Anything else i should look into before chopping cables for a new harness and/or in the last moments of desperation, buying a ecu?

 

Some people have a problem with the sensor that tells you the door is open. It drains their batteries, but it won't say the door is open.

 

Fixed that when I got the car with a quarter inch of duct tape.

It only drains running.

 

Sorry then, I can't help you in that case.

 

Thanks anyway. I may put the ecu back in and check the blink codes. Not much else I can get done in the rain.

 

Are you using an amp(s) and sub(s)? you could just have a cheapo battery.

 

I have 2 amps and a sub. 200w/4ch and 250w/2ch. setup for over 2 years without issue.

I originally thought this might cause some type of stress but while testing everything has been off and the battery tested fine in the shop. Its less than a year old.

 

So the problem has just came up recently?
Did you add fog lights or HID's?
Think back to if you added something that might be doing it.

 

Thought about that. I've only changed a brake light about 2 weeks ago and even tried taking it out.

Just tried to get blink codes with the paperclip method and got nothing.
Tried swapping batteries, same issue.
Disconnected amp positive, same issue.

The rain has started again. Planning for the next test, alt. wire harness plug.

 

Keep us posted. Good luck.

 

Like I thought from day 1, it was the alt. Demanded a new one and everything is aok.