Radio Wiring and What I’ve learned (Updated 03/16/2021)
Since the head unit article was published, I’ve had a few questions about wiring a later model Nissan stock radio into the S13 without cutting the stock harness. For those that are familiar with car audio bare with me, some of us are getting our feet wet and a basic audio setup is as far as I’m ever going to go. Before I was able to do anything, I had to replace the stock harness/plugs because they were cut. If you own an S13 and find yourself in the same position, this is the harness that you need:
To wire a head unit without doing any cutting, you will need the following harness, it plugs directly into your factory harness (and the above harness) leaving you with wire extensions (just like you would have after cutting your harness) to wire directly to an aftermarket harness.
Connecting a later model Nissan/Infiniti head unit is the same as an aftermarket unit. Unlike an aftermarket unit, stock head units do not come with a wiring harness, so you can either cut the harness from the car you are taking the unit from or simply buy a new one. Let’s take a look at the head unit I just picked up.
Here’s a rear shot of it. For this to work, it has to be compatible with my system* and I will need a nissan OEM radio harness for a 1995 or higher.
NOTE* to my knowledge, all these units will not work with the factory speaker system and will require you to run new speaker wire.

To complete this setup, the 1995 harness plugs into the head unit and the loose wires are color connected to the loose wires from the adapter harness. Using the proper adapters ensures that your factory harness stays intact and your wiring clean.
Below you will find the wiring Key for 1989 + Nissan/Infiniti vehicles.
Wiring diagram for 1989+ Nissan/Infiniti OEM radios.
Thanks for posting this information! Excellent for an audio noob like myself.
My pleasure.
Hi
Any idea on the what wires needs to go on a factory CD player, 5 din pin from the cassette deck and what 4 wires needs to be hooked up?
That’s just the thing, you don’t need to “think” or do any custom wiring. You need to get the proper harness adapter for your car. All the wires are labeled so you can easily match them to any aftermarket or OEM harness.
Thanks so much for this info. I’m doing the reverse swap (a 1991 radio into a 1995 vehicle) but just having the pinouts and connectors listed is super helpful.
Glad you found it useful.