I have a 1989 Civic DX Hatchback with the 1.5. Brought the alternator to Pepboys and it tested good. Bought a new battery. Put the alternator and new battery in. Drove to Pepboys again and had them test the alternator in the car. Tested good. Somehow the juice from the alternator isn't getting to the car. According to the voltage meter the voltage keeps dropping as I drive. I drive for half an hour and the voltage went from 11.5v to 10.7v. Then I pulled the positive terminal off the battery and the car shut off which it shouldn't do. AND the battery warning light is on. When I rev the car up the light goes off then comes back on when the rpm's drop.*Also all the fuses in the car are good. What's my next troubleshooting avenue? Thanks in advance.

 

Took the whole engine wiring harness out of the vehicle. Checked every inch of the charging wire, all good. Ima put it back in and start the car with the charging wire disconnected and check the voltage at the alternator terminal. I checked it before but with the wire connected. It had the exact same voltage as the battery which makes sense. It was probably reading the battery voltage.

 

it's probably your alt. one of the diodes/regulators in side might be faulty.

 

That's what im thinking but Pepboys checked the alternator TWICE and said it was good. Could they have been wrong?

 

Check your grounds bro maybe.go to another store to get it.checked

 

Checked all the grounds, good. Ima put my foot in someone's a$$ if the alternator is bad. They checked it out of the car AND in the car.

 

Definitely the alternator. I disconnected the charging wire from the battery and put a voltmeter to the alternator terminal and it was only putting out 1.3 volts. Im sueing Pepboys.

Thanks for your input everyone.

 

Lol

 

Sounds like my car. Same thing, 90 Civic DX.

I'm not a Honda guru, but I have been wrenching for 30 yrs or so.

I wound up putting new grounds from my engine to the chassis. I also found that the ECU wasn't fastened to the chassis I reseated the connector in the fuse box for the ELD (from what I understand, it's "electronic load detection"...honda's attempt at additional fuel efficiency).

Hasn't missed a beat since.

 

they can check it as many times as they want, it'll always read good on their machine. you could go to any other parts store and they'll come up the same.
unless you take it to a garage and they hook your car up to a electrical load machine, it'll read good.

it's because your alternator just has a faulty diode/regulator. if only one is bad, you'll still have the other 5 or 7 (alternators usually have ether 6 or 8 diodes/regulators) which will still be able to read ok. there is a terminology for it, but i don't know what it's called.