Replacing your stock Z31 Radio with an Aftermarket head unit

So you got your Z and want to listen to some tunes but your Stock Head unit is just not cutting it any more. Upgrading your Z31 Tunes isn't a hard job but will take some work to do it correctly.

So in the 80's Nissan was one of the companies that decided to show what they can do with Technology and the 300ZX is a fine example of top of the line 80's Tech. The Audio system in the 300zx had many advance features for its time. Some of these include, Digital tuning, External Amplifier (depending on Model), 4 or 6 speakers (depending on Model)Voice Warning System (Bitchin Betty), Antenna Half Mast Operation, Steering Wheel Controls, and Diversity Tuning. I'll explain what all this means below.

Because of the Advanced features found in the 300zx, installing your aftermarket head unit will require more work than just buying a mount kit and harness connector. Here are some of the things you Run into when tackling this upgrade.

Parts Needed

  • Head Unit
  • Mounting Kit (part# METRA 99-7411)
  • 16awg or 14awg double strand Speaker wire
  • Electrical Tape
  • Crimp connectors or soldering iron
  • wire cutters
  • wire taps

Removal of Factory Head Unit

First step of removal of the factory head unit is to disconnect the (-) battery Cable from the battery. This keeps you from shorting out the circuit and blowing fuses.

Now place the hand brake on and move your shifter to the rear most position.

Pull the ash tray out with a firm tug to reveal the two screws that hold the lower part of the bezel. Now with a Phillips #2 screwdriver remove the two screws that were behind the ashtray. With the same screwdriver remove the two upper most screws that are hidden under the lip of the top of the trim bezel.

With the bezel loose, Carefully pull the bezel out to gain access to the connectors for the lighter and its light. Unplug these and place the bezel in a safe place.

Now you have access to the radio and climate control bracket. This is held in with 4 10mm bolts. Two on top like the bezel and two on the bottom under the head unit.

With these bolts removed you can pull the radio and climate control out to access the electrical plugs. Carefully remove all the plugs and pull the mount out being careful not to hit your shifter.

With the mount removed you will see the screws holding the stock head unit to the mount. Remove all 4 screws and the stock unit should slide from the mount including the trim panel.

Now that you have the unit out you will see the wiring harness for the stock head unit. Depending on your model (gl or gll) you will need to wire your new head unit to this. This is where Tap connectors come in handy to not cut your stock harness. Below I will list the Wires to look for and what they will need to connect to on your new aftermarket harness.

Wire Use

Stock Color

Aftermarket Color

12V+ Switched power

Yellow with Green Trace


12V+ Constant (memory)

Blue with Red Trace



None in harness

Black ( Ground to chassis )


Green with black trace

Blue with white trace
( Check your Manual)


Red with Green trace

( Check your Manual)

Right Front(+)

Red with White trace


Right Front (-)

Red Solid*

Grey with Black trace See *

Left Front (+)

Blue with White trace


Left Front (-)

Blue Solid*

White with Black trace See *

Right Rear (+)

Red with black trace (GL)
Red with Green trace(GLL)


Right Rear (-)

Red Solid (GL)*
Red with Yellow trace(GLL)

Purple with Black trace See *

Left Rear (+)

Blue with Black trace(GL)
Light Green with White trace(GLL)


Left Rear (-)

Blue solid (GL)*
Light Green with Black trace(GLL)

Green with black trace See *

*Common Ground

The GL models use a common ground system for the speakers. A common ground system is where a common ground are shared between more than one speaker. The 300zx Z31 has this type of wiring from the factory. The Z shared common Ground between Front and rear speakers per side. Left side share a ground and right side share their ground. In order to wire your newer aftermarket head unit, You will need to split this out so each speaker has its own grounding source to the head unit.

An easy way of doing this on is to run new speaker wires to either Front or rear speakers and use the stock wiring for one. In my case I used the stock wiring in the harness for the front speakers and then ran new wiring to the rear. This way you also keep the Voice Warning system Intact.

Voice Warning System

The 300zx came with a Voice warning system that many call "Bitchin Betty". This system provided a warning for 5 conditions. I will list them below.

  • Left door is open
  • Right door is open
  • Lights are on
  • Fuel level is low
  • Parking brake is on

The Voice Warning system only was available in the 1984-1986 GL and GLL models. Base (SF) models and all 1987-1989 did not have the voice warning system.

The system works by interrupting the signal going to the front left speaker and replacing it with the Voice Warning signal. The signal is generated by the voice working module located above and behind the ECU in the passenger kick panel. Sometimes it is hard to see the module as usually insulation is placed over top of it.

The System only uses the Left front speakers and no amp is needed for it to work including a radio. Most people loose this function by replacing the wiring with new for the front speakers.

Half Mast Antenna Function

In the 1984 to 1986 models Nissan installed an antenna switch for full height/half mast operation. This feature was not very useful but was one of those 80s cool things. Having the antenna at half mast height reduced the reception performance. If you wish to keep this function, you can easily move the switch to the new stereo plate and plug it in. The switch is just a single pole single throw switch if you need to replace it. If you don't care about it, you need to connect the two wires that were plugged into the antenna switch so the mast operates at full mast.

Steering Wheel Controls

On the GLL models, Steering wheel controls were offered for some basic functions of the head unit. These functions include the following:

  • Power on/off
  • Tape selector
  • Tuner band
  • Scan
  • Volume control wheel

The steering wheel controls are operated off an LED built into the steering wheel and the steering column. The LED sending unit is a box in the steering wheel and sends a signal to the LED receiver unit built into the steering column. This box also consists of a transmitter box to send a signal wirelessly to the receiver located under the rear compartment (2 seater) or rear seats (4 seater). Removal of the receiver box will remove your cruise control functionality. Most aftermarket headunits can use these signals via a converter box like the PAC SWI-X converter.