aaronth777
Proven Member
- 92
- 26
- Apr 12, 2015
-
Dayton,
Ohio
Hello all, I have a few questions regarding the charging system in a 98 gsx. I've had some charging issues so I replaced my alternator with a new one, not remanufactured. When the car starts and it's cold, it'll put out a full 14v. However as the car warms up and I drive it around, the voltage slowly drops to 12.1v. When the fan comes on and I turn the headlights on, it'll drop to 12.0v, and stay there, only going back up to 12.1 when the fan turns off and I turn the headlights off. I tried a few things and found that if it's running at 12ish volts and I unplug the 4-wire harness from the alternator, it'll immediately jump up to 13.5 volts and slowly climb to 14. So this tells me that the alternator is fine, it's the wiring or the signal it's receiving from the ecu.
My question is what should the 4 wires be reading on the 4-wire alternator harness? I know the green and white wire both go to the ecu. Should they be grounded, 12v+, or just floating? I've read that if the white wire is grounded then the alternator will be in "low voltage mode", only putting out 12v, but not sure about the green wire. The red wire goes to the 40a headlamp fuse, and it's putting out 12v+ regardless if the headlights are on or not. I have aftermarket HIDs if that makes a difference or not. And then the black/yellow wire goes to the alternator relay, which I do not have in my car. My battery light works in my dash (it's slightly dimmer than the rest of the lights, idk if that matters), so I read that I don't need this relay for the alternator to work properly. My car also has a code 1500 "generator fr terminal circuit malfunction" if that makes a difference. Any help is appreciated!
My question is what should the 4 wires be reading on the 4-wire alternator harness? I know the green and white wire both go to the ecu. Should they be grounded, 12v+, or just floating? I've read that if the white wire is grounded then the alternator will be in "low voltage mode", only putting out 12v, but not sure about the green wire. The red wire goes to the 40a headlamp fuse, and it's putting out 12v+ regardless if the headlights are on or not. I have aftermarket HIDs if that makes a difference or not. And then the black/yellow wire goes to the alternator relay, which I do not have in my car. My battery light works in my dash (it's slightly dimmer than the rest of the lights, idk if that matters), so I read that I don't need this relay for the alternator to work properly. My car also has a code 1500 "generator fr terminal circuit malfunction" if that makes a difference. Any help is appreciated!