Help me identify wires! S13

[StryfeS13]

So I pulled out my fuse box harness today to begin my relocation but I noticed a few things wrong with it.

First off, alllll of these wires were cut and taped up near my passenger side fuse box.



They lead back into the harness where it enters the passenger side of the firewall




Next I found these wires cut..which I believe to be the starter relay. The car had a push button start, is that possibly why these are cut?

[compactfean]

All those wires used to go to a tcu for an auto.

[StryfeS13]

You're sure?

5 Speed 240sx's dont have a TCU? I thought you need that for the dash, chimes, wipers, etc..?

[Hijacker]

I think he meant to say ATCU. The wires go into the car through a grommet on the passenger side of that car that manual cars won't have.

The wires match the colors from the AT solenoids. If you want to compare, go to page AT-26 of the service manual.

As for the starter wires, AT cars don't have clutch interlock relays like MT cars. Most times, whoever makes the swap to an MT jumpers the park/neutral switch at the plug to give the car the ability to start anytime. Looks like whoever had this car before was trying to be slick about it and hide the splices inside the harness.

[compactfean]

Yeah what hijacker said. Lol. My car used to be an auto and I was able to get rid of that entire harness on the passenger side by getting rid of those wires and bringing the wiper motor plug under the hood instead of behind the fender.

[StryfeS13]

Okay so I can just leave those wires taped up or remove them in genereal.

What about my cut starter relay wires? Can I just wire them back to the starter relay and call it good?

[Hijacker]

Autos never had the relay. It was put on USDM models. If the car starts, I would just leave it be. As for the rest, you can remove them. They should all go to one of the plugs on the side of the relay box, or he may have left them going to the ATCU. Not sure which end he cut off from the pictures. Either or, they're aren't used anymore. The only wires you need to keep from the trans are the wires from the old inhibitor switch that run your reverse lights, but that's on a separate plug.

[StryfeS13]

Well yeah the car started but it was push button start before. No key was used to start the car.

[StryfeS13]

Alright! So I followed and cut out those "ATCU" wires. They all went to these plugs...





I also found this bundle of cut wires, what do you think these are?

[Hijacker]

The picture with the two black plugs, the one in the back looks to be the one that bridges the ATCU to the ECU. E116/F5. The one in the foreground, I'm having trouble pairing it up with the service manual.

As for the mystery bundle, I'm not quite sure. I have a dissected chassis harness from a base model MT coupe in my garage. I'll run out and take a look at it sometime today and see if I can find that plug. If it's AT related, though, it won't exist on my harness.

[StryfeS13]

I just took the "mystery bundle" and deleted it.

You know by chance which relays I can remove that wont screw up anything else?

[Hijacker]

Oh, you can remove a lot of stuff >_> As far as relays go, there's really nothing associated with the auto trans that can be deleted. I would just suggest pulling out the wires you know go to the ATCU and its associated switches, sensors, and solenoids. Go through the AT section and EL section of the service manual and make notes on what you have on your harness versus what's in the wiring diagrams. If you can match up the plug to the harness layout diagrams, you can find out what part of the service manual should have a diagram for you to look at. In sections like the AT section, if you go forward to the Trouble Diagnosis page, it will have a sub-table of contents and the wiring diagram will be listed there. Sections like that typically don't list the diagrams in the main table for some reason.

When I started working on my custom main harness, I probably spent a few hours going through the service manual, section by section, to map out what could be removed. Since I did that, I have a fairly comprehensive list of every wire that passes through the Super Multi Junction connector under the driver's dash. I ended up pulling out around 26 circuits, and associated relays, but since I swapped to a Silvia front, a lot of those were related to the pop up motors.

[compactfean]

I wish I could get rid of my pop ups just for that reason! So far I've made it from deleting all extra a/t wires to the atcu, removed and consolidated all the wiring in the fuse box (added a spot for fan relay) and removed other power window/seatbelt wires. Also removed all extra wires that go to the trans (vg trans swap) so all I have is speedo and reverse. Im at a point now where I'll have to start pulling stuff apart up to the smj to finish ”gutting” my harness.

[Hijacker]

I removed all the stuff related to pop ups, AC, clutch interlock, headlamp timing unit, and the associated relays. I added a circuit for my e-fan, a circuit for the coil packs like the JDM units would have, and I split signals the circuits for running the parking lights so the silvia side markers will work. I did find out that S13s have provisions for fog lights already built into the harness, but there's no mention of it in the service manual.

The idea was to have a custom harness that would look factory to anyone who was under my hood.

[liquid_cool]

omg..what a mess man...first thing i would do is weel and deal a new used harness..thats a friggin franken built nightmare..and after getting a new harness man..id burn that thing so it never enters the 240 comunity again!..sucks you have to go throu this due to some franken builder butchering up that precious 240 to death..thank god you saved her!

[SoCal-S13]

Next I found these wires cut..which I believe to be the starter relay. The car had a push button start, is that possibly why these are cut?

[StryfeS13]

Alright so I'm just about done with the tuck...The car used to be an auto as we've figured out since it had the ATCU plugs. I have removed all of that crap. Also since it was an auto it had no clutch interlock relay. How are the black/yellow black/white wires ran on an auto car then?

These two...can I just connect them together?

[compactfean]

On an auto it goes straight from ign switch to starter. Its the black wire/white stripe.

[Hijacker]

On an auto car, the park/neutral safety switch is what keeps the car from starting in gear. That's why the circuit gets jumpered during conversions since the switch is removed with the auto trans. Fean's correct on the wire colors, but since your harness has been hacked into, telling you where the are is a bit of a pain. I can tell you that both wires are thick since they carry a fair amount of current. The B/Y wire would have ran from a 2 prong plug under the pass. fuse box down to a 2 prong plug going to the lower harness. Just look for a B/W wire running from the driver side across the front and the B/Y that runs to the lower harness then make sure they're connected somewhere in the middle.