1990 CRX battery, alternator, or groundwire problem Help

[Virginia]

1990 CRX Si: My car after it has warmed up idles weird then eventually dies. The idle will go from sitting idle up to 1.5. When it dies it won't restart without jumping it. (Also the battery dies when it is just sitting.) When it dies while driving, the battery and engine light come on.
So I replaced the battery and the car starts after sitting for a while. But has the same problem with the idle then it putters out. So I replaced the IACV and test drove it. So far I haven't had the idle problem, but the battery light comes on when I press the brakes or turn on my lights. Not sure if it is going to die. When I hit the gas, take my foot off the brake, or turn the lights off the battery light goes off. Do you think that my alternator is on the fritz? If I unplug the battery while the car is running would I be able to tell that way??? I tested my alternator with the multimeter, it was good. Maybe it's intermittent. Any help would be great.

 

[efhondakid]

Check all your grounds and it might bet the alt getting ready to quit working, but check all your grounds first.

 

[Virginia]

Thanks, I checked the grounds....they were good. So I check the belt next.

 

[jlicrx]

sounds like a bad alternator to me - start it up and disconnect the battery - if it dies, the alternator is bad

 

[Fernpatch]

Replace the alternator.

 

[M3DoW]

I have the EXACT SAME PROBLEM... I bought a new alternator but it still continues to happen and my grounds have all been checked so idk what the problem is!!!

 

[Dual-500]

The ECU controls the alternator. Take it from there - wiring or ECU.

How did you test Alternator with a volt meter? That would have to be done while driving the car, with loads like fans, and lights on.

 

[dc4dude]

Mr. 500 is right. What he is talking about is a load test, check the voltage at idle, and at. About 1500 rpms no loads, record results. then turn on hi beams, blower motor on high, and rear defrost at idle, record results, loads on at 1500 rpms. Then compare results. It should be no lower than 13.0 volts and no higher than 15.0 volts... Or something like that...

 

[Dual-500]

Let me add. I strongly suspect the alternator itself. It's not at all uncommon for a weak battery to take out the alternator or a weak alternator to take out the battery. Many times, when one needs replacement, the other needs replacement as well.

A weak battery won't take a full charge, nor will it handle peak demand loads very well - thus placing more demand upon the alternator. The condition of the battery after starting the car will be close to dead and alternator will try to charge it each cycle of a car being turned off for a period of time allowing the battery condition to further deteriorate and then have to crank the engine. This additional load being placed upon the alternator can damage it over time.

On the bad alternator condition. A defective alternator won't bring the battery to peak charge condition. Battery life is a function of charge condition over time. So, over time an alternator that's not getting it done will take out the battery, shortening the battery life considerable. When we replace battery only, with defective alternator that's limping along, it just starts the cycle over again. The new battery may last 6 months to a year and fail again.

Never replace alternator or battery without testing the other. Full charge and load test on the battery, load test on the alternator.

As the alternator is controlled by the ECU in Honda's. Removal of the alternator and bench testing will tell if the alternator is in good condition. It won't guarantee it will function properly in the vehicle. Wiring and ECU also play a role. Hence, my suggestion to load test it in the vehicle, by monitoring battery voltage with full electrical load on it. Headlights on high, heater or A/C blower cranked up, engine warmed up with radiator fans running, driving with engine running up from idle.

That is the only way to know if the alternator is getting it done when installed in the subject vehicle.