Battery light stays on, battery and alternator tested ok.

[Chanss_r]

I have a 89 Nissan 240. The battery light comes on once I turn over the engine. It goes after have the speed reachs over 45. I check out a few threads but my problems seems different because the brake light is not coming as well. I took it to Advance Auto and the battery and Alternator test okay. Any ideas?

Thanks

[benemorius]

You're right - your problem is not like others. Give me a few more details and we'll see what we can some up with:

Do the battery light and brake lights come on when you turn the key on before starting the engine? (be sure your ebrake is down otherwise that will cause the brake light to stay on regardless)

What is it you're saying about 45 mph?

[Chanss_r]

Sorry for the late response.

Yes, all lights come on when I start the car but the battery stays on. Yes after going 45 MPH, the light will go off and I am not noticing that it goes of if I have been driving for awhile. Also if after going over 45 MPH, I have to stop at a stop light, the light comes back on until I pick the speed up.

[benemorius]

I'd check the fuse under the hood labeled Eng. Cont., but really this makes almost no sense. The output from the alternator must be high enough to turn off the bulb check relay (and thus the brake light) but still low enough to light the electrical light. I guess you could backprobe the white-red wire in the connector on the alternator with a voltmeter and see what the voltage is.