Engine Subharness

[cronux]

okay, in the sohc to dohc swap, it says you need a new engine subharness (tranny harness) if you switch from auto to manual. i have a 89 chassis, and a 95 engine. i am using full s13 dohc electrical up top, im just wondering if the 95 automatic subharness will plug into the s13 dohc engine harness, or if there is a difference between s13 and s14. and i only need the speed sensor to work, i dont care about anything else.

[S14DB]

S13 and S14 VSS are different. I thought the S13 MT harnesses were the same sohc and dohc.

[cronux]

i have a 97 transmission. and a 95 subharness. i just want to know if that subharness will plug in my s13 dohc harness.

[S14DB]

No, you need a S13 VSS and harness.

[cronux]

god dammit. i have to wait fucking again...

EDIT: i could still get it running without hooking up the vss right?

[g6civcx]

god dammit. i have to wait fucking again...

EDIT: i could still get it running without hooking up the vss right?

The motor itself will physically run, yes. Most ECU uses the VSS signal to adjust idle speed. You may not notice a difference, but it will help the engine run slightly better.

Use the VSS that's correct for your gauge cluster. You can calibrate the VSS signal between the VSS and the gauge cluster but it's a pain.

[projectRDM]

The auto lower harness will also have the starter, alternator, and OPS wiring. It can be used (and should anyway) since the manual harness won't plug into an auto fusebox. The VSS won't effect anything by not being plugged in.

[cronux]

nah, its a 89 manual body, with the tranny from a 97, the auto subharness from a 95, 95 engine, and then s13ka engine harness. so i need a manual one to plug into the manual fuseblock then right?

[S14DB]

Yes you Manual one should work. Just hook up everything but the Tranny sensors.

[cronux]

i dont have a manual one. i have a 95 engine, a s13 engine harness, a 97 tranny, and a 89 manual body. i also have my left over 95 automatic tranny harness, and want to know it it will work.

:edit so do i need a manual tranny harness is the question?

[g6civcx]

The auto lower harness will also have the starter, alternator, and OPS wiring. It can be used (and should anyway) since the manual harness won't plug into an auto fusebox. The VSS won't effect anything by not being plugged in.

These plugs on the tranny harness should be reused if possible.

On the tranny itself the only plugs you need are the VSS and reverse light. Everything else may be left disconnected.

The ECU does do something with the VSS signal, but for all intensive purposes it's not noticeable. A lot of shops recommending connecting the VSS signal between the speedo and the ECU, but a lot of people leave them off without noticing anything. Your choice.

[cronux]

okay, stupid newb question, i thought the vss was for the speedo, as well, so if i leave this unplugged, then my speedo wont work, right? but the lower harness also has the starter, so that has its own plug? or am i just a retard..?

[g6civcx]

i thought the vss was for the speedo, as well, so if i leave this unplugged, then my speedo wont work, right?

Correct. No VSS signal no speedo.


but the lower harness also has the starter, so that has its own plug?

Each item listed has its own plug. The wires ride on the same harness for compactness and durability, but each connector has its own plug to the individual component.

[cronux]

okay, so will my 95 tranny harness have a plug that fits right into the plug from the s13 engine harness?

[g6civcx]

okay, so will my 95 tranny harness have a plug that fits right into the plug from the s13 engine harness?

No. You need to reuse as much of the S13 lower harness as possible, and cut/splice as necessary.

Lay out the S13 engine harness, the S13 lower harness, and the S14 lower harness over the actual engine and transmission you're going to use. Open your FSM for the correct year S13 and S14.

Look at it and think about it for a second.

[cronux]

i dont have an s13 lower harness. at all.

i had an automatic s14, that was totaled. then i took the engine from it. and used a s14 manual tranny, and put it in a sohc body. then i bought a s13 DE engine harness. i still have the automatic s14 tranny harness, and was wondering if there was any posible way i could make it work.

[projectRDM]

The lower harness plugs into the underhood fusebox.

89-90 cars uses the same plugs as the 91-94 cars, but the harness is physically different since the alternator and power steering pumps are on opposite sides.

The 95-98 cars use a different harness with different plugs, they will not work on any S13 chassis.

Additionally, auto and manual versions differ per year as well. In fact, the 97-98 lower harness is even different from 95-96s since the later models use a 4wire rear O2 sensor, not the early 3wire.

Viewing an FSM for each chassis will tell you all you need to know.

[Snott Rocket]

"The lower harness plugs into the underhood fusebox.

89-90 cars uses the same plugs as the 91-94 cars, but the harness is physically different since the alternator and power steering pumps are on opposite sides."

So you could not use a lower MT harness from an 89 - 90 on a 91 - 94 AT chassis? I ask because I'm wanting to use a SOHC MT harness for my 5 speed swap into a 91 DOHC harness. That make any sense?

[projectRDM]

"The lower harness plugs into the underhood fusebox.

89-90 cars uses the same plugs as the 91-94 cars, but the harness is physically different since the alternator and power steering pumps are on opposite sides."

So you could not use a lower MT harness from an 89 - 90 on a 91 - 94 AT chassis? I ask because I'm wanting to use a SOHC MT harness for my 5 speed swap into a 91 DOHC harness. That make any sense?

You could, but after cutting the shit out of it, shortening wires, and then having no provisions for the reverse switch, you're better off just clipping the auto harness at the case and hardwiring the switch. Everything else will plug right up. Basically 60 seconds versus 30 minutes.