1999 Nissan Sentra GXE Headlight Problems - Please Help!

Yes, I can help. Please respond with answers to these exciting questions...

1) Do you have the daytime running light option? 2) How are you determining precisely that the "high beams" are lighting up? It's a bit tricky to tell with a 2 headlight 9004 system. Are you looking at the actual bulb filaments to make this determination? 3) What exactly do the headlights do in the low beam position?

I think I know what is wrong, but will wait for the above specifics.

Regarding your blower problem, I think that if you inspect the blower switch and switch connector behind the center HVAC panel, you will find them melted and/or blackened. Your system runs all fan current through the blower switch. It's a problem waiting to happen if the switch is not designed to handle a constant 10 amps and spikes upwards of 20 amps. (or if the terminal contacts loosen over time from thermal cycling)

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I guess it wasn't that important.

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Well, actually it is important. I haven't had a chance til recently to check it out again and get answers to your questions. Sorry 'bout that.

So here it is:

There is no daytime running option.

Normal mode on the switch, the top filament lights up fully, and the bottom filament does nothing. When the highbeams are on, the top filament is lit, but dim, and the bottom one glows orange, but does not fully light up.

I hope this is what you were looking for, again sorry for the slow response and I look forward to hearing from you again!

Thanks, Jason

Thanks, that's exactly what I needed.

The most likely cause of this problem would be high resistance at the common headlight ground terminals E13 and/or E25. The first thing I would suggest you do is find these grounds, remove and clean them.

housing. It's possible that you will have to remove the housings to see them, but I have no way of knowing this for sure. Look for a 10mm head bolt with one wire/ring terminal per side.

This would explain the shared voltage and resulting dim elements and also the high beam indicator being on even in low beam mode.

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info, they appear to each be under their respective headlkight

I know which ones you mean, I have the wiring diagrams here too. We were unable to find those points before, the wires bunched together then went into some different holes, but I didn't try removing the housings to find them. I'll give that a shot as soon as I can and let you know what I find in the next couple days. Thanks!!!!!

info, they appear to each be under their respective headlkight

I hope it isn't too difficult to find those ground points. On most asian cars of that era, removing the bumper skin aids in headlight housing removal and may allow you to see the wiring harnesses better.

I ran out of time yesterday, but the test for a poor ground is as follows... you can measure voltage at the black ground wires at each headlight connector with the lights on (and in the dimmer position where they act the most screwy). To do this, backprobe the black wire with your positive lead, then ground your meter on the battery negative terminal. Anything over about .3 volts is a sure sign of a poor ground.

This is a simple circuit, so if you want to splice in an appropriately gauged additional ground you could also do that. I would suggest a

14g wire for each headlight. I like to fix things back to OEM condition, but this is another viable option, and electrically speaking it will cause no harm if done right.

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