1987 Nissan Maxima stereo replacement help.

[vaultroamer92]

Hello all,

The factory stereo in my 1987 Nissan Maxima has been giving me problems recently so I decided to replace it. I picked out a Sony CDX-GT575UP and ordered it from Sonic Electronix' eBay store. After receiving the unit I wired it up to the Scosche harness that was included and proceeded to connect it to the appropriate connectors behind the dash. I turned the car on to test everything and the stereo turned on fine but no sound, no static, nothing was coming out of any of the speakers. Since I've never installed a stereo I called Sonic to see if they could help me out. After getting transferred a few times I finally was told to call Scosche and see if they could help me out. My car has an equalizer that apparently has an amp as well so the guy at Scosche had me bypass the amp by connecting the blue wire w/ a white stripe (amp) from the harness to the red (power) wire on the stereo. After doing this the stereo would make noise like it was going to turn on but wouldn't actually turn on. I then hooked up the stereo the same way I had it originally and wired the violet and violet w/ black stripe wires (right rear speaker) directly to one of my speakers. The stereo would turn on but still no sound came out of the speaker. I then tried the grey and grey w/ black stripe wires (right front speakers) directly to the speaker and lo and behold it worked. However during all of this I discovered that if I disconnected the violet w/ black stripe wire the stereo lost power. The guy at Scosche said it sounded like the stereo might be bad and suggested I try a different stereo which I don't have. I'll be able to borrow one on Sunday but I figured in the mean time I would see if anyone online had any suggestions or could help me.

As a side note the factory stereo still works fine, it just has a loose connection somewhere inside the unit that causes the left speakers to cut out. I hooked it back up and everything works fine. I'm not sure if this is how it's supposed to work but the factory stereo only works if the equalizer/amp is hooked up to it. Since the stereo and equalizer/amp are factory they have some really strange proprietary connectors so I can't hook the new stereo up to the factory equalizer/amp.

Thanks in advance for any advice!

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[vaultroamer92]

Ok so here's a bit of an update. I hooked up another stereo and it is having the same issues so I know it's not my stereo. I was looking at the wiring harness from Scosche and the plugs that connect to the harness. The plugs that come from the stock wiring in my car don't have wires running into some of the slots so essentially the wires that go from the Scosche harness SHOULD work but they aren't able to plug into anything so that's probably my issue. So I suppose my next question is this. Should I contact Scosche and see if they can get me a different harness that will work or should I look around and see if anyone else has a harness that looks like it will fit? Or would it be better to try and find the original wiring diagrams for the car and either have it rewired or wire it myself?

Another side note is that I noticed when I unplugged the stock stereo and stock amp/equalizer my fans have gone a little wonky. They work but every time I turn the key to ACC the fans will cut on and then off. They also randomly shut off when I have the fans running. It almost seems like the fans were somehow wired into the stereo or amp/equalizer.

I have a feeling I'm going to end up needing someone to look at it and do it professionally. I really don't want to do that because of the excess cost. At the same time I don't want to do it myself (although I'm certain I could) because I fear I would wire it up wrong and end up with some of my electrical systems not working.

 

[keep_hope_alive Premium Member]

seems like the Scosche adapter doesn't properly interface with the stock amplified system.

figure that the stock radio feeds other components before feeding the speakers. one simple solution is to bypass the stock speaker wiring and just run new wiring from the new head unit to each of the speakers. this will ensure everything will work properly. i typically bypass factory amplification when making head unit changes.

another alternative is to try a different harness.

Metra Part # 70-1764 | Nissan wire harness | Metra Online

you'll notice that this harness includes RCA output jacks to allow the new head unit to feed signals to the factory amplifiers. it also includes amplifier turn-on wiring (which is what the guy on the phone was trying to get you to do).

if the inputs to the stock amplifier are unbalanced, then it can be shorting out the aftermarket speaker outputs.

modern head units have a "balanced" or "differential" output - meaning there is signal on both positive and negative outputs. older stereos did not have that wiring method and the negative output was grounded. if you short a speaker wire on the aftermarket deck, it won't output sound (buy can stay on).

you can try the Metra harness for amplified 1987-1994 Nissan Maxima and probably have success Or you can just bypass all factory speaker wiring and wire each one directly. While you are in there, replacing the speakers is worth the effort (and a good use of the money you saved thanks to DIY).

 

[vaultroamer92]

seems like the Scosche adapter doesn't properly interface with the stock amplified system.
figure that the stock radio feeds other components before feeding the speakers. one simple solution is to bypass the stock speaker wiring and just run new wiring from the new head unit to each of the speakers. this will ensure everything will work properly. i typically bypass factory amplification when making head unit changes.

another alternative is to try a different harness.

Metra Part # 70-1764 | Nissan wire harness | Metra Online

you'll notice that this harness includes RCA output jacks to allow the new head unit to feed signals to the factory amplifiers. it also includes amplifier turn-on wiring (which is what the guy on the phone was trying to get you to do).

if the inputs to the stock amplifier are unbalanced, then it can be shorting out the aftermarket speaker outputs.

modern head units have a "balanced" or "differential" output - meaning there is signal on both positive and negative outputs. older stereos did not have that wiring method and the negative output was grounded. if you short a speaker wire on the aftermarket deck, it won't output sound (buy can stay on).

you can try the Metra harness for amplified 1987-1994 Nissan Maxima and probably have success Or you can just bypass all factory speaker wiring and wire each one directly. While you are in there, replacing the speakers is worth the effort (and a good use of the money you saved thanks to DIY).

Thank you for your help. I did some more research and took a more detailed look at the factory connectors. I was able to find a wiring diagram in my Hanes manual for the stereo and it detailed the stereo and speaker wiring for the vehicle. It had two different diagrams, one for US model Maxima's and one for Canadian model Maxima's. After mapping out the wiring and figuring out where everything went I started to look at the factory connectors. I discovered that the connector in my vehicle is in fact the Canadian model setup and not the US model. I also noticed that the Scosche harness lined up fine for both power wires, illumination, and ground but all 8 wires that were supposed to go to my speakers simply dead ended at the factory connector. I contacted Scosche again to see if they carried a different harness that would actually fit my car and instead of listening to what I was saying the tech guy on the phone said I needed to buy an FAI-3A Interface. That was an additional $15 and didn't look at all like it would work. Instead I just used the half of the Scosche harness that fit provided power and did in fact work. Then I cut the factory connector that went to the amp/equalizer (leaving some extra wire in case I need to reattach the connector) and wired the speaker wires coming directly from the stereo to the wires that run to the speakers. I'm happy to say that all 4 speakers are working perfectly now, I didn't have to run new wire so that was a plus. Hopefully this information can help someone else with similar issues. I will upload the wiring diagram I used when I get the chance.

 

[keep_hope_alive Premium Member]

Thank you for your help. I did some more research and took a more detailed look at the factory connectors. I was able to find a wiring diagram in my Hanes manual for the stereo and it detailed the stereo and speaker wiring for the vehicle. It had two different diagrams, one for US model Maxima's and one for Canadian model Maxima's. After mapping out the wiring and figuring out where everything went I started to look at the factory connectors. I discovered that the connector in my vehicle is in fact the Canadian model setup and not the US model. I also noticed that the Scosche harness lined up fine for both power wires, illumination, and ground but all 8 wires that were supposed to go to my speakers simply dead ended at the factory connector. I contacted Scosche again to see if they carried a different harness that would actually fit my car and instead of listening to what I was saying the tech guy on the phone said I needed to buy an FAI-3A Interface. That was an additional $15 and didn't look at all like it would work. Instead I just used the half of the Scosche harness that fit provided power and did in fact work. Then I cut the factory connector that went to the amp/equalizer (leaving some extra wire in case I need to reattach the connector) and wired the speaker wires coming directly from the stereo to the wires that run to the speakers. I'm happy to say that all 4 speakers are working perfectly now, I didn't have to run new wire so that was a plus. Hopefully this information can help someone else with similar issues. I will upload the wiring diagram I used when I get the chance.

thanks for following up. good work.