420A 420A Battery Good, Alternator Good, but won't charge

[joshuadyer1218@gmail]

PLEASE HELP!

So i have a 98 eagle talon esi that just recently had a battery light pop up, followed with rough idle and trouble getting the rpm's up to shift when driving.

Low voltage is what i assumed, checked the battery and diagnosed that the alternator was not charging the battery. i took the old alternator off and went to o'riellys and tested 3 times came back good. Then took it to autozone and it tested good aswell. I have installed the old alternator back on and have looked at every diagram, there is no relay between the connector and the fuse box. checked all the wires that come off the alternator and they are giving me the voltage from the battery, so there is not any bad wires, i guess. Im stuck with how the alternator tested good, but wont charge the battery!

 

[steve]

On the 2gNT cars the PCM (ECU) controls the alternator voltage regulation via the two wire connector on the alternator. If you're not seeing 13 to 14.5v at the battery while the car is running then the PCM isn't causing the alternator to charge the battery.

 

[Mello]

Have you checked the fusible link for the "generator" (#1)? It should be a big square blue thing that looks like a strange fuse and 100A.

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[joshuadyer1218@gmail]

PLEASE HELP!

So i have a 98 eagle talon esi that just recently had a battery light pop up, followed with rough idle and trouble getting the rpm's up to shift when driving.

Low voltage is what i assumed, checked the battery and diagnosed that the alternator was not charging the battery. i took the old alternator off and went to o'riellys and tested 3 times came back good. Then took it to autozone and it tested good aswell. I have installed the old alternator back on and have looked at every diagram, there is no relay between the connector and the fuse box. checked all the wires that come off the alternator and they are giving me the voltage from the battery, so there is not any bad wires, i guess. Im stuck with how the alternator tested good, but wont charge the battery!

REVISED:

Although i took the alternator off and had it tested, both oriellys and autozone just gave a dummy light (Good or Bad) said it was good. Never showed them what it was putting out, after diagnosing the ECM as you mentioned, i bypassed the ground from the ecm which was connected to the plug that ran into the harness. The alternator was giving off 18V which means the ECM was doing its job regulating the output of the alternator, causing it to shut the alternator off, which gave us low voltage causing the engine issues. So i replaced the alternator and charges like a champ! Thank you guys!

 

[joshuadyer1218@gmail]

I have 98 eagle talon esi that all of sudden the charging system light (battery light) came on. Before everything i changed the alternator and the battery. I have checked all the fuses and connections but have not located the problem. It currently does not hold a charge. Is there any one who has experienced the same thing?

 

[chrysler kid]

Yeah. The alternators from the autoparts stores are pretty crappy quality from 90's era mexico. I swapped one out under warranty last week and this week I heard it rattling, and 2 of the housing bolts had rattled out

The one before that had a stripped out bolt mounting hole, had to get a longer bolt and put a nut on it

I work at an autoparts store and can tell you that 90's era remanufacturing was terrible. 1 in 5 would be bad out of the box. Combine that with these cars being rare now and some of these alternators have been on the parts shelves for 20 years

 

[joshuadyer1218@gmail]

Yeah. The alternators from the autoparts stores are pretty crappy quality from 90's era mexico. I swapped one out under warranty last week and this week I heard it rattling, and 2 of the housing bolts had rattled out

The one before that had a stripped out bolt mounting hole, had to get a longer bolt and put a nut on it

I work at an autoparts store and can tell you that 90's era remanufacturing was terrible. 1 in 5 would be bad out of the box. Combine that with these cars being rare now and some of these alternators have been on the parts shelves for 20 years

Even if there testing good? The one i replaced and the new one i got both tested good.

 

[chrysler kid]

Even if there testing good? The one i replaced and the new one i got both tested good.

So bench testing the alternator inside the store can have different results than testing the charging system on the vehicle

While running at hot idle you should be able to see atleast 13.2 volts at the battery. If the voltage is lower than that, the power from the alternator is not reaching the battery

You would then want to test voltage at the battery fuse on the fuse box, or voltage directly on the back of the alternator

If you shorted the power from the alternator power wire (its easy to do because there is tight space behind the atlernator) you could have blown the alternator fuse on the fuse box.

Again the best basic test is to make sure the alternator is good is while the vehicle is running and fully up to temperature. Bench testing can be inconclusive because it does not introduce heat and other variables in the equation