Hi everyone,
I am a college student. I do not have money to send the my car to dealer. I hope you guys may help.
I have a 2003 accord coupe 2.4 with 89,xxx miles
My battery light came up couple weeks ago. I knew it should be the alternator problem, but I was tight on $$. I did not get it fixed.
Finally, the car went out of battery at school. It could not start. I jumped it up. After 20 sec., it dead again. I did not want to get a tow, so I bought a alternator n a battery from AutoZone n replaced at school. It ran fine, but the battery light was still on.
Then I took it back to AutoZone. They replaced me another alternator. and the 2nd alternator was tested, good. After installation, the battery light is still on.
The voltage is about 12.5v when the car is off.
12.3v when the car is on.
In the morning (when the car is cold), the alternator does not work.
After driving 3-4 miles, the alternator starts to function. (Voltage is about 13v-14v) n battery light goes off.
I though that was the problem with the belt. I replaced as well, but it didnt help.
personally I think it is electric problem because it works sometime.
Does anyone can direct me where i should start to check?
thanks

 

Check the wiring harness to the alternator, look for some insulation rubbed off & wires sometimes touching ground.

I don't have a wiring drawing any more for that car, but there's one wire in the harness plug that's a control wire. Under certain conditions, the PCM can "shut down" the alternator by grounding that wire. If it's shorted to ground by worn insulation, that can shut down a good alternator even when the PCM isn't sending that command. There's no load on that wire, so grounding out won't blow any fuses. But I don't know what color wire it is.

 

There could be a problem w/ serpentine belt, too worn and loose, or perhaps the tensioner is not adequately tensioning the belt. This could cause inadequate drive to the alternator. However, if belt were slipping there usually would be some noise, but perhaps not if very loose.

It is also possible the harmonic balancer/crankshaft pulley has a worn bushing (rubber sandwiched between outer drive pulley and inner hub connected to crankshaft). There are cases where this results in driving until battery is dead. In some cases the Alt light does not come on, but that may not always be the case.

Is your Alt light on all the time? Are you monitoring voltage? A voltage monitor (Equus 7721 at amazon or similar) will tell alternator voltage when is going too low.

good luck

 

The Alt light is on sometime. usually when the car is cold, it is on.
after driving 3-4 miles, the Alt light is off.
I checked the voltage. It is about 13v-14v when the light is off
and it is about 12.3v when the light is on
Checked all the fuses, connectors, ground on frame...
what else should i work on?
thanks

 

There is as a pointer gauge on the drive belt (serpentine belt) auto-tensioner. With the car running, take a look at the pointer gauge, if it moves around with the car running, the auto-tensioner may need replacement.

 

is my tensioner still good?
thanks

 

That position is OK, but check dynamics. It should be steady, perhaps not at that location however.

good luck

 

the tensioner is not steady when the engine runs. It was moving back and forward.
is that normal?
thanks

 

That is not normal. The tensioner may be the source of the alternator charging problem.

 

How far back & forth? Some small movement should be OK, like 1mm at the pointer?