Assorted '90 Civic issues I could use some help with...
 

I have a '90 Civic with a 1.6L, fuel injected, auto, 201k miles. Driving home from work recently, my battery light lit up as I was at a stop light. Since this happened 3 years ago, (https://www.hondacivicforum.com/foru...ad.php?t=29061) I immediately suspected the alternator was once again failing. I brought the car to the same shop that had replaced it in 06 and after testing it, I was told it was going out. Since I have a lifetime warranty on the alternator I had it replaced. Now when the engine idles after being warmed up (around 900 rpm) the batt. light gives a faint flicker. I have no power or performance loss, the car starts, runs and drives normally besides that flicker.

Weak battery? Bad cables? A short somewhere? I'm replacing the battery today to see if that fixes the problem. The current battery is 3 years old and was the cheapest I could find when I bought it.

Also, on occasion, when I shut the car off and restart it within a few minutes (like after getting gas or making a quick stop at the store), the car will start, run normally for a few seconds, then sputter and die. Immediate attempts to restart it don't work. I usually have to let it sit for a few minutes and it will restart with no problems. This never happens on a cold start. Only after it's been warmed up.

Last one. On cold days when I park my car at work, home, etc. and shut the motor off. The key sticks in the acc. position. I can't turn the key all the way off until the little gear indication light lights up in the "P" position. Again, only during colder (75 degrees or colder) weather. I'm thinking it's a sensor in the shifter (that won't allow one to take the key out when the car is in gear) is worn out. But confirmation from one or more of you out there would be awesome.

I realize it's an old car with a lot of miles and I should probably get something newer but at the present time that just isn't possible. Plus, aside from these issues, which aren't much more than annoying, this car has been very good to me. I'd like to get a few more miles out of it before I sell it or put it out to pasture.

Thanks in advance for any info or advice I can get.

Is the ECU under the passenger carpet blinking any trouble codes?

Replacing the battery is probably a good idea. Also check whether the alternator belt is loose. Alternatively, some rebuilt alternators come bad right out of the box.

For stalling, you might consider resoldering the main relay.

For sticky lock, purchase some special lock lubricant. I think you can find some at Walmart.

Haven't checked the ECU.

If a new battery doesn't fix it I'm taking back to the shop to make sure the belt is tight. I had a new alternator put in. I don't mess with rebuilt for stuff like that. Too many horror stories.

Is that difficult? I'm not very literate when it comes to cars.

Not sure what you mean by sticky lock. A little more, please?

Your new alternator could be a dud. It does happen. The "battery" light is controlled by the alternator and it really isn't sensitive to the condition of the battery.

The main relays were a problem from the factory. A lot of them eventually get bad connections. As a preventive measure everyone who owns a 88 to 95 Civic should take it out and re-solder it. It may not be causing your stalling problem though. Check for codes like Ron said.

The interlock system is probably the switch on the shifter. I think it is the same circuit that lights up the "P" light on the dash. If the switch doesn't agree that it's in park you can't turn the key all the way to lock and take the key out.

I think the alt is fine. I've been driving the car with this issue for a couple weeks and it hasn't gotten any worse. I'll definitely have it checked, though.

Gonna do that today or tomorrow.

Should I just replace it? Or is it possible (not to mention safe) to just bypass it in some way?

Thanks again for the info, by the way.