Hi, I have a slight problem with electrical system in my '91 CRX Si. I was going to NYC one day and my battery light came on when I was
going on a highway at around 60mph. I didn't pay too much attention, untill I got stuck in traffic and my stereo went down, then my lights
started becoming dimer and finally my tachometer stopped working. I was sitting in traffic an my car was ideling, but whenever I reved the
engine and brought my rpms up to about 3K, everything worked fine as long as I kept rpms at that level. Then my engine stopped working once I stopped at the toll booth and we had to push it in order to start. Now its weird, my battery light comes on whenever my car is idle.
When I drive everything is normal, but when I stop and my rpms drop below 1K it comes on again. Is it my alternator or is my battery that
weak that it cannot be recharged? Thank you,

 

take the battery to autozone or what ever you got similar to that, and have them test the battery first. if its bad change it. if the problem still persists after you change the battery, then go check your alternator. thats just my opinion,,,,

 

Turn your car on and then disconnect the negative terminal from the battery. If the car dies, then your alternator is bad. I'm not sure how to test the battery other than taking it to a auto store.

 

Sounds a little like an alternator problem. Was it raining or cold out? You say it works fine when you rev up to 3k, your alternator belt could be slipping under 3k and you rev it up it catches. This would be obvious if you here that belt "screech." I was having this problem whenever it was raining or cold out. I also have a weak battery, but it should be turning off things while your car is running. Just check the alternator belts tension.

 

i say alternator. the guy that posted above me is probably right but when your battery light comes on in your car and your car doesn't die it is probably the alternator.

 

Bad idea to disconnect the ground cable while car is running on a ECU equipped car. The voltage SPIKE can fry the ecu.

 

if you haven't changed your alternater by 120k, do it. mine went at 130. same with my dads. in order to get mine out, 1990 CRX Si, i had to also remove the alternater bracket. it was in the way...

 

Its more than likely the alternator if you havent guessed already, If the car has high mileage it could just need new brushes. They are available at the dealer for around 20-30 dollars. It requires rmoving the back of the alternator and replacing them. Mostcases can be done in the car.

 

i had almost the same issue.. it was teh alternator! it's a #$%^ to take it off. you have to take the master brake cylinder to get the alternator off. and I use the test stuff( take the ground cable while the car is running... if your shuts off then it's the alternator.. if it doesn't .. i would suggest to take it off and have it tested .. it's probably starting to die on you)

 

My ride just did exactly the same thing. It is the alternator. You might as well get a new rebuilt one with more amperage. I replaced mine myself but its a bitch to get out and get back in. Sill doable though. Good luck and tell us how it goes...

 

My car has 180K miles on it and I do believe that the alternator is original. How long does it take you replace it? If I have to take my master cylinder off, does it mean that I have to screw around with my brakes and then refill the break fluid? Since winter is coming and I don't have a garage I am pretty much fucked. How much would you normally pay for an alternator? Any sites where I can find it?

 

A easy way to tell if its your alternator that is bad is while the car is running at idle, put a volt meter across the battery. If the alternator is good, it should read ~13.5-14.5 volts. Then turn the car off. The battery should read ~12 volts with the car off. But also make sure the belt is good and tight first.

No, no, no....don't take the alternator out the top of the engine bay by taking the brake master cylinger off. Its just makes your job harder! You have to take the left front wheel off and then unbolt the alternator. Then take the alternator bracket off of the block. The alternator should then come out between the left front suspension. Put the new alternator back in that little area behind the engine and then reinstall the alternator bracket onto the block and then install the new alternator and then tension the belt.

I just recently replaced my alternator and it cost me ~$150 at NAPA but I got ~$50 back when I brought back the old alternator. Good luck.