EricCR

Make sure the sensor is not dirty or dusty, it's right there on top of the dashboard, near the windshield. There's a sun load sensor for the AC and the light sensor for the headlights. If it's scratched (e.g. when cleaning the interior) it can also trigger sooner as it's perceiving less light. You can use Meguiar's PlastiX or something similar to remove the scratches. I don't think there's a way to adjust the sensitivity unless you tweak the resistance values by intercepting the signal/wire. The service manual must have the low/high values for that sensor.

I used the head unit's pre-amp outputs and a harness adapter with RCAs so it's mimicking what the factory Bose head unit did: sending low level signals to the amp. The only issue is that the Sony I chose (AX4000) has rather weak 2V outputs so volume is a tad low, but it's still louder than my ears can take it at max. I also have a LOC that I purchased from Crutchfield (PAC-ROEM-NIS2) just in case my plan A (using the pre-amps) wasn't loud enough, but I haven't felt the need to install it. The stereo beeps are relatively quiet. The whole thing sounds exactly like it did with the Bose head unit, just with more flexibility thanks to the EQ, time alignment and crossover settings. I hated the Bose's very limited bass and treble options. I'm in the same boat. I don't mind the Bose amp+speakers one way or another. I know it can be much worse or much better. My speakers seem to be intact, not blown or distorting, but the front set, for being components, are definitely not great. The tweeters have no definition and mid-frequencies could be clearer. I'd also prefer not replace the amp. Bypassing it is easy enough. I found these instructions and I like that you don't need to take apart half of the interior to lay new wiring, just crimp some existing wires together. I guess if I were to commit, the best option would be a 50/50 approach. Keep the rear speakers driven by the factory amp and bypass the front amps and put a good set of components, driven by either a small amp or the head unit. For now I think I'll keep the Polks in a drawer since I don't think it makes sense to replace Bose components with aftermarket coaxials.

I have 4 coaxial Polk Audios (DB651) that I removed from another car where I upgraded everything. The Polks still work just fine and sound good for what they are. They have surprisingly good bass for being 6.5". I also installed a Sony head unit in the Pathy a few months ago, but I'm still using the factory amps and speakers. It sounds ok-ish, as these Bose systems did, nothing to write home about but serviceable. Now, instead of throwing the Polks in the trash, I thought that perhaps they could find a new home in the Pathfinder, but I have no inclination to add a dedicated amp or anything else, so they would be powered by the Sony's head unit. The car is not used often enough and I have 3 other rust buckets where I would rather invest in audio. Would you leave the Bose system alone, 200W amp (allegedly), 22 year old paper cone speakers or would it be sightly better to drive the Polks from the HU's amp (about 20 RMS x 4) and bypass all the Bose stuff? I'm sure the new speakers would sound better, but I'm not so sure how much the Bose amp levels the play field with the stock 1 Ohm speakers. If anyone has bypassed the factory amps and can share their experiences, I'm all ears.

I had to order everything individually. Finding the right bolts was a particularly painful endeavor. Buy the arms from Rockauto, for the bolts you can either find the closest match at your local hardware store (or online) or get a kit which is what I did but they tend to be on the expensive side. There was an old thread that specifies the right bolts you need. You can replace everything at home but it's 99% guaranteed you won't be able to remove the old, rusty bolts. They need to be cut.

Not sure what the question is, but yeah, the amp fuse is confusingly the one that controls power to the stereo. Back when I had it, I had to pull that fuse sometimes after I modded the cassette player with an AUX input. The cassette deck "thought" there was a cassette stuck in it at random times which necessitated the good old fuse reset. My guess is that your amp fuse was loose or is glitchy or something else in the fuse box is wrong (corrosion, loose wire, bent tabs).

My GF used to have a Sentra B13 years ago and those two bulbs failed (recirculation and A/C) and we never found replacements. I know this is not it, but for anyone interested in the digital climate control module, it has easily replaceable bulbs, they're called T5 which you can find pretty much everywhere: https://www.amazon.com/gp/product/B0CKZCYTXM?smid=A12JRGT98I4B0G&th=1

Are you after an actual improvement in light output and pattern? Or are you mostly looking for an aesthetic change? If it's the former, you should do what I did. None of the Chinese eBay "projector" headlights will be good. Those projectors are usually meant for H1 halogen bulbs, have a very narrow beam pattern, crappy output and blurry cutoff. Here's my car: If you're mostly after halos and other sort of DRLs, I can't help you with that but there are places you can ship your headlights to to get them modded (e.g. Lightwerkz).

I was never satisfied with my factory reflectors. I restored the lenses and they were crystal clear, I used the very best H4 bulbs from Koito, checked voltages and they were still too dim, so I retrofitted HID projectors. Trust me on this: No LED bulb, no HID bulb will give you proper illumination if you stick to the stock reflector. Not only will you be glaring everyone but the light pattern will be terrible with dead spots, low CRI and mediocre low and high beams. Here's the result: The beam pattern on those aftermarket headlights is very likely awful. Put your car against a wall at night and turn them on. I'm sure there's no clear hotspot, cutoff and no width to the beam at all. Designing a headlight reflector is not something any generic manufacturer can do well. Also, if you do a proper HID projector retrofit, there are plenty of options that are pure white, not blueish. In HID the blue bulbs are usually the cheap ones and LED bulbs also tend to be 6000K or higher.

That's good info on the PAC steering wheel module, if it's glitchy I might skip it. I also had that planned but I honestly didn't use the steering wheel controls that much, in any car. I'm a perfectionist and I hate having things in the car that don't work so that's my only motivation but I've always found easier to just reach out and use the head unit controls instead. EDIT: This is how it ended up looking BTW:

I almost bought the PAC line output converter but thought that using the preamp outputs was a more elegant and correct solution. It's just that voltage needs to be a tad higher since you can't play with amp gain. As far as I've read these amps can't be adjusted. The plan is to eventually replace the whole factory setup so for now this is good enough.

Thanks, man! It was the amp remote signal. I was using the wrong wire from the adapter harness (instructions that came with it are worthless so I struggled a bit, should've gone with common sense instead). Anyway, it's all good now, EXCEPT for one detail: Apparently these Bose amps expect at least 4V coming from the pre amp outputs. The Sony I bought (XAV-AX4000) has 2V so volume is a tad low. You have to really crank it up (volume bar goes from 0-50 and under 35 it's inaudible unless it's very quiet outside). The max volume is just on the edge of what's comfortable so I'm not too upset, but if the audio source is quiet you'll be struggling. I didn't research this beforehand. I don't blame myself as it's something too specific and would've never stumbled upon that unless looking for it, but there you go, in case someone else is thinking using the factory amp with an aftermarket head unit: don't skimp on preamp voltage.

I just installed an aftermarket Sony stereo on my 2003 and I have the same issue, i.e. the stereo powers on and works perfectly but there's no sound. I used a harness adapter with RCA (pre-out) According to the service manual (EL section), the BOSE amp only powers the rear speakers. The fronts are driven straight from the head unit. Is that true? I'm checking to see if I wired the amp remote properly, but shouldn't I be getting audio from the front speakers even with the factory amp off? Is the amp also powering the front speakers through this "audio amp relay" circuit?

Yup. I wish the R50s had separate high beams so this wouldn't be an issue. In any case, it's not something I use that much. I found more useful my mod of being able to turn on the fog lights with the parking lights, especially when I need a bit of light, but not a gamma ray burst. Projectors can look aesthetically weird and can be a lighting downgrade, depending on what you go for. I've had great results with Morimoto and I especially love how wide and gradual the beam pattern is. Some projectors are extremely narrow and put too much light right in front of the car, which kills your night vision. The only thing that I don't like is that blue tint on the lenses but apparently it's a special coating. Pathy looks a bit surprised now, but for someone who is not that familiar with R50s it could pass up as OEM. Heck, the R51 had a version with projectors and looks, dare I say, more aftermarket?:

I didn't realize I never posted the results of my projector retrofit. My original reflectors were borderline dangerous at night and trying LED bulbs in them only made things worse (no light on the road, glared oncoming traffic). I used Morimoto Mini D2S 5.0 bi-xenon projectors with Morimoto ballasts, round chrome shrouds and standard Osram D2S bulbs. I didn't paint the reflector bowl as I prefer a more OEM look. I may upgrade to Osram Lasers at some point in the future (or M-LED projectors) but for now this is more than enough light, better than most new cars. The only downside is that flashing your high beams causes the ballasts to quickly cycle on/off which wears them down, so I try to avoid doing that. This is my 4th retrofit and by far the easiest. Original headlights are super easy to take apart, they need minimal modifications to fit the projector and the only real drawback is that nothing prevents the projector from rotating, so adjusting the cutoffs is a bit of a pain. Low beam pattern and cutoff:

Thanks, guys! The folks at 4x4parts offered me a good deal so I got their bolt/nut kit. Even getting only 8 of 54368-0W02A at Courtesy Nissan was more expensive than what I ended up paying, so all good. Still a bit more than your solution @hawairish, but not too bad all things considered. Is Mevotech "Supreme" good quality for the 4 arms with bushings?