I'm new to 300ZX ownership so apologies for the number of questions I'm asking. 

I'm acquiring components to upgrade the infotainment system, this includes an Android head unit with matching amplifier connected by SPDIF. 

I understand that if my car has the Bose system I'll need a bypass, but I don't want to buy one if I haven't got Bose. 

So my question is, how can I tell if it does or doesn't without taking off a door card or rear speaker enclosure? 

Take the rear speaker cover off (they pull up and off). If you have a black plastic speaker enclosure then they are

Bose  (if you see a speaker mounted on a metal bracket then you have a non-Bose system).

Bose speakers were always fitted front and rear as a set from the factory.

EL90-91.pdf

Edited January 3Jan 3 by AndrewG

Having just seen your post about buying that lovely grey UK spec Zed, I'd say you'll have the OEM Clarion amplifier on the rear speakers, which most UK-spec cars came with. 

So yes, if you want to upgrade your system without using the OEM amp, then you'd have to by pass it. As far as I know, you won't need a by-pass kit - you should just be able to re-wire the rear speakers. Which you'd no doubt be doing, when you install your after-market amp anyway!

If you decide to keep the OEM amp, then all you have to do is ensure that the amp has a live power feed from the new head unit, otherwise the rear speakers will not work! The "Nissan-to-ISO" adapter kit does not facilitate this (it didn't when I installed a new head unit), so I had to bridge the connection from another live feed, on the head unit side of the adapter. I think I used the electric aerial one....

I take this means it's not Bose.

RicharsS, where would the Clarion amp be situated? 

They look like this and are under the speaker mounted lower down. 

 

15 hours ago, KD88 said:

I take this means it's not Bose.

RicharsS, where would the Clarion amp be situated? 

 

I'd say you don't have the Bose set-up; and it looks like someone has already fitted after-market speakers in there. It's quite common, as the original 6x4 speakers will be past their best after 30 years - although they probably weren't that great in the first place!

Lee has posted a pic of the Clarion amp above - and an insight as to its location. I can't remember where it it in my Zed, I don't recall seeing it inside the speaker enclosures, I thought it was behind one of the rear boot panels, next to the suspension turrets. But I could be wrong 😉 

My series 4 had the amp and it was located down where the ABS unit was to the right side.

Obviously not under the ABS cover but rather under the speaker side.

 

6 minutes ago, JaiKai said:

My series 4 had the amp and it was located down where the ABS unit was to the right side.

Obviously not under the ABS cover but rather under the speaker side.

 

That sounds familiar Lee.... I would have seen it when I removed the trim, to replace the boot/fuel flap release cable.

On 03/01/2025 at 20:30, KD88 said:

I'm new to 300ZX ownership so apologies for the number of questions I'm asking. 

I'm acquiring components to upgrade the infotainment system, this includes an Android head unit with matching amplifier connected by SPDIF. 

I understand that if my car has the Bose system I'll need a bypass, but I don't want to buy one if I haven't got Bose. 

So my question is, how can I tell if it does or doesn't without taking off a door card or rear speaker enclosure? 

I did a search on that every connection to the speakers will have 4 wires on the connector when you open the housings the speaker is connected as usual with 2 follow this 2 and you I’ll find the speaker wires 😉

Btw I got the JL c1 speakers and I queried if I need an amplifier.. very happy with the results as is just thinking to add an integrated amplifier/woofer for bass low frequencie and leave the speakers alone as a high frequency controlled by the head unit Less wiring 

and you will need this

https://www.ebay.co.uk/itm/185251812710?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=g_UaOp-ZS5a&sssrc=4429486&ssuid=bWDN5m4JSrq&var=&widget_ver=artemis&media=COPY

And the adaptors for the front and back 

I've test fitted the new head unit without the new amp connected. I've got sound to the front speakers but not the rear. There is a Clarion anp below the off-side speaker, will this be preventing sound to the rear? 

There's also this connector down there, is this for the amp and speakers? 

My apologies I put the wrong wiring diagram for a UK spec up before. The one below is correct. The Clarion amp will have had a signal

from the stock radio to switch on. The Clarion amp will also have received line level L&R signals from the radio for the rear channels. You can

trace the various wires used from the UK spec wiring diagram (the photo shows the Black/White and Blue/White wires and are the stock right

channel output from the Clarion amp). The Red/Yellow/Brown set of wires and white connector is for the rear electronic shock absorber actuator.

EL-93 (UK spec).pdf

Edited January 12Jan 12 by AndrewG

In short, yes, the clarion amp is preventing the rear speakers working. I had the same issue - it's because the after-market adaptors from Nissan to ISO do not provide for a power supply to the amp.

You can either re-wire your old speakers or, as I did, bridge the after-market adaptor leads to deliver a live feed to the amp connection. It's easy to trace the amp's power feed from your loom - then you just pick one of the live feeds from the new head unit cables and connect it to the amp feed wire in the car. 

Worked for me - I kept the Clarion amp in place and it works fine 😉 

That's a great help (I think).

So the Clarion amp has to receive power from the head unit for the rear speakers to work and the only way for them to work from another amp is to re-wire them?