So my car was vandalized while in winter storage......Someone had the bright idea of trying to steal a 98 Bose deck as if you could get a dollar for it at your local pawn shop and mangled the head unit. I have been dreading this replacement due to all of the information I read, boy did I over study this one. I ended up giving the car that I purchased to keep off the road for another 10 years until it was a "classic" to my son when he graduated. If I need a radio when driving a 18 year old kid must have one. In short he ran to Best Buy and dropped $130 on a Pioneer DEH-150-MP and the Mettra 7550 wire harness.
I am posting this because EVERYTHING I have read said that this would not work. You need the 7551, a 4 ohm deck won't work with the Bose 2 ohm speakers etc. etc. etc.
I hooked it up color for color, only issue was the black ground from the Mettra harness needed to be grounded further back than the part that the radio screws into. Maybe once all installed the ground will continue through but I would recommend getting it back to some of the rougher metal you will see.
It sounds 20 time better than with the stock unit. Rear speakers actually produce some thump and while it doesn't bang like my 04' G35 the quality is better I would argue, just not as much base but the 98 doesn't have the sub in the middle of the back window like the 04.
In short:
Don't be scared to go the obvious route. I literally laughed at my son and almost didn't hook it up for him as everything I read said it would not work under any circumstance.
I was going to replace the stock head unit, $120 + shipping was the cheapest I could find it. $10 more and there is a modern head unit, way better sound with AUX input and RCA input for a amp and sub should he wish to go that route.
Quick FYI-
I don't know if we have steering wheel cruise control or not but I don't use cruise and he wouldn't bother to take the time to figure it out.
Hopefully this helps alleviate anxiety for anyone that has been sweating over the same install.
Feel free to email should you run into any problems, I am an electrical contractor by trade and could probably solve some basic wiring issues as the principles are the same.
I really hope this helps someone, I have received so much invaluable information on these forums I felt it was my obligation to share my experience in the hopes of reciprocating.
I may post video if anyone wants and will probably diagram the sub install which I am tackling this or next weekend

I put in an aftermarket Pioneer unit and the installer used a $29 adapter for the Bose and the sound is way better than the stock unit. Getting to stream rocks, couldn't do CD's and FM radio anymore, I am amazed how great those Bose speakers sound with a better source.

Can you tell me what the part number for the adapter is, or provide a link to it? Can't figure out where I can buy it. Thank you.

Just call Crutchfield they will know what to sell you, they are cheap. I don't know about the exact part they used, all I know is I was worried about it and wanted to update the sound system to modernize the car, they immediately had an off-the-shelf part that did the job for 30 bucks.

So technically 'any' headunit would work on this car?

Crutchfield doesn't list any wiring harnesses for a 99 Q45... I know the harness has 2 sets of RCA plugs on it to plug in to the aftermarket stereo. That powers the amp and such. I am stuck though, because I want to put a sub in the trunk. Anyone done that yet? lol

Thanks to this thread I've upgraded my Head Unit using a 7550 adapter... Just like Ebixler said, its as easy as matching the colors.

Are you referring to the Metra 70-7550 Adapter Harness?

Skibane wrote:Are you referring to the Metra 70-7550 Adapter Harness?

Yes that is correct. As well as the antenna conversion.

I like the looks of that. I own a 92 Q, and the Bose OEM has issues (static, balance, etc), not to mention how passé cassette tapes are. The 92's had (I believe) powered speakers front and rear. Is that same as in the 97 models? I guess what I hope to know is will this same setup play well in 1992 model.

Also, can you let me know the model of the receiver you installed?

TY.

Looking at the schematic in 1992 FSM, the audio wiring between Bose unit and powered speakers is shielded. This says that signals are low level, in comparison with signal levels to non powered speakers, as are output by off the shelf receivers. Can anyone say if the adapter harness attenuates audio signals?

All of the Bose systems have powered speakers.....GRRR..I used a Pioneer 3600 replacement unit which is working great, however, I am starting to get drop outs on the various speakers and so if i am still driving this car in 2-3 years I will be looking at replacement speakers and power. However, if you are still good with head unit your probably good to just drop in a replacement head unit. I am still more than fine save the occasional drop out at some speaker location.

Don't know if I'm too late but I still have the 1997 receiver I took out. Casette player does not work but all else is well.

For that matter I do too with working cassette, but the cost is so small to buy a decent double DIN unit why replace with the old POS....Drake, pay shipping and I will send you my old 97' as well.

Does anyone have a diagram for the stock harness they could post?

I just got a 1995 Q45. The HU was AFU. Cheapest replacement was $90 on Ebay. I wanted to add an AUX input or a full blown Bluetooth interface, so I bought a 2006 Altima Bose HU for $30. bought a Metra reverse harness for it and a radio harness for my 95 Q45 Bose HU. They both have 16 pin connectors, different from one another. The Metra harness for the 95 Q45 only has 13 pins, so I had to jumper the ILL Control, Amp Power On, and a chassis ground to the 2006 Altima harness. I connected a GROM AUX1 NIS02 aux input adapter(XM Sat version). I had to do some cutting to make the dash trim piece fit, but sounds great. I still using the original; Bose speakers and amps. I wired a dual USB power outlet in line with my front cigarette lighter with a 5 amp in-line fuse. It sounds great, and only cost me $127 total. That's for altima HU ($30), ALtima reverse harness ($9), Q45 harness ($4.73), GROM aux in kit ($66), antennae adapter ($6.54), and $10 in miscellaneous parts.

Charlie,
very interesting, I have a 94. Can you post some photos and perhaps some wiring notes.

Search posts by q45guy who was making these adapters for the G50. At least a couple of his posts had the schematic for making the cables you describe.