LS1 To S13/S14- Engine Harness Installation Guide

Wiring Specialties | 458 Danbury Rd, Unit A9 | New Milford | CT | 06776 | [email protected]
LS1 To S13/S14- Engine Harness Installation Guide
Thank you for purchasing the Wiring Specialties pre-made wiring harness. Please read these instructions carefully before
attempting the installation.
This LS1 Engine harness is designed to work with all LS1 engine platforms based off a 99-02 Fbody or GTO ECM
installed in an 89-98 Nissan 240sx chassis.
NOTE: For easier wiring fitment, install the harness on the engine PRIOR To installing the engine in the car!
NOTE! We will begin by connecting all the engine components first then proceed to the interior of the
car to connect the ECU and the interface connectors.
Feeding the harness into the car
Remove the PCM covers and feed the
harness through the firewall with the ECU
(PCM) and the interior interface plugs
leading the way.
On the S13/S14 chassis the diameter of the
firewall opening is small and will likely
require the fan box to be unbolted to create
more space for the PCM to slide through.
Wire Layout
Starting at the front of the engine, drape the
harness over the EFI parts.
Refer to the last page for complete
connector identification.
TIP- It is easier to lay out the LHD Driver
side connectors first (this side contains the
Alternator and TPS, MAF wiring
connectors), followed by the passenger
side, and finally the transmission drop,
which should be dropped behind the V of
the heads and down to the bottom of the
This is a picture of the LHD Driver side
When installing the injector connectors, use
the longest branches for front injectors and
the shortest ones for the rear injectors.
Crank Sensor / Starter
Some engine mounting kits have the
headers close to the block and will require
the starter to be lowered to reach the crank
sensor connector.
Two ring terminals are found on the
passenger side of the harness.
The Start Signal is the smaller, polished
ring with the black wire. The Larger silver
ring terminals is the Alternator power wire
(red) and should be installed on the MAIN
power terminal of the starter. A battery
cable should be installed on the same
terminals of the starter. MAKE
ABSOLUTELY SURE that the two
terminals do not come in contact with each
other. Some GM factory battery cables will
need to be filed for correct fitment. OEM
240sx battery cable can be used as well.
Coolant Temperature Sensor
This engine harness is designed to work
with the 99+ 2-pin F-Body/GTO coolant
temperature sensor. The picture shows a
sample of the correct sensor required.
Nissan Coolant/ Oil Gauge Adapter
The Nissan coolant and oil pressure
sensors are required for factory gauge
cluster operation.
The adapter kit offered by WIRING
SPECIALTIES allows the OEM S13/14
coolant temp sensor to thread into the rear
passenger head, and the OEM S13/14 oil
pressure sensor into the block in the factory
GM oil sensor location. The Nissan oil and
coolant sensors can be found on your
Nissan engine.
Nissan Coolant Gauge (Non adapter)
Alternatively, tap the coolant passage on
the passenger side head to 12x1.25.
Then, connect the 1-pin temp connector to
the Nissan temp sending unit.
The factory Nissan temp gauge requires a
Nissan temperature sensor. This 1-pin
sensor can be found on your factory Nissan
engine. This sensor needs to be installed in
the GM head for proper operation.
Oil Pressure Sensor (Non adapter)
If the adapter kit is not used, you will
receive a factory GM oil pressure sensor
connector. Make sure to use the oil
pressure sensor designed for the oil
pressure light as shown.
If the connector on the harness does not fit
the sensor, you can either replace the
sensor or install the connector from the
original GM harness . It is very easy as the
terminals should simple re-pin from one
connector to the other. Excludes GTO
Harness Ground
The main engine EFI ground is located at
the factory GM location on the back of the
LHD Driver-side head. Use the stock bolt to
secure the ground.
Reverse Sensor
The reverse sensor connector is located on
the US passenger side of the harness and
is a 2-pin black connector with a green
rubber seal.
Due to various engine installations,
transmission tunnel may need to be
modified for proper fitment of the reverse
Install the connector with the transmission
lowered or engine out of the car.
SGI-5 Speedometer
The speedometer Calibration box should
be setup as followed:
Power-Pink Wire
Ground- Black w/ White Stripe
Input- Green w/ White Stripe
Output 3- White
All Dip Switches Down
*** Refer to SGI Manual for calibration
The Wiring Specialties harness includes
relays, fuses and wiring for two electric fans
and is designed to work with any factory or
aftermarket style fans. The harness side
connectors can be found in the front of the
passenger head. The male mating
connectors and terminals have been
supplied along with the harness, and
should be wired to the fans using the
following wire layout.
BLUE - Fan 1 Signal +12v
GREY - Fan 2 Signal +12v
***Make sure to test fans for airflow. Air
must be pushed or pulled towards the
engine. If needed, reverse polarity on the
fans by reversing the fan side wires.
T-56 Transmission sensors
To avoid improper installation on the
transmission sensors, a diagram has been
provided. Again, note that laying out the
harness in the early stages is crucial for
proper fitment.
4L60E AutomaticTransmission
Included with the automatic version of the
LS Harness are two subharnesses for
Park/Neutral Safety Switch and the
Reverse Switch. Each has a mating end on
the fusebox and must be wired into either
an aftermarket gear selector switch, or
directly to the transmission. (Setup may
vary based on donor vehicle)
Park/Neutral Safety Switch- This
subharness must be wired into a gear
selector switch to provide a signal to the
starter in the park position
Reverse Switch- This subharness must be
wired into an automatic gear selector for
the use of reverse lights
Main Power Interface
This covers both S13 and S14 chassis
S14 (top picture)
Plugs into the LS harness by the ECU with
a white rectangular connector and into the
S14 chassis harness with the white
connector with a black over. Make sure that
once installed, the chassis interface
connector has the latch lowered to fully
secure the connector in place.
S13 (bottom picture)
The Grey and Dark Brown 8-pin connectors
are plugged into the 2 chassis connectors
by the S13 US Passenger Headlight.
In the passenger foot-well we find the dash
connectors (white and brown). The White
connector is used for the SOHC 240sx
(1989 and 1990) and the Brown connector
is used for the DOHC 240sx (1991-1994).
Connect the correct interface plug to the
dash connector behind the glove box
(remove the glove box for easier install).
Connect the ECU and tighten the mounting
bolt lightly.
Install the LS fuse box in the white
connector, closest to the PCMs.
S14 Wipers
Connect the wiper motor plug (White for
95/96 models and Grey for 97/98 models).
REMOVE the unused connector by cutting
the clip off and taping up the exposed wires
Wiper Amplifier & Cruise Control
Make sure to connect the Wiper Amplifier
(black or brown box mounted on the inside
of the fender, next to the wiper motor) to
the black 8-pin connector in the picture.
The 4-pin grey connector is used for Cruise
Control available on the SE/LE 240sx
models. Just plug it into the CC module.
For ABS users, please make sure to use
the connector shown in this picture and not
the Grey ABS connector, as they will
Auto to manual Conversion Option
For Auto to manual conversions, connect
the two Grey extension plugs to the
firewall-side of the fuse box, where 4
chassis plugs are located.
Auto connectors are located on the right
side of the fuse box in the image. You will
need to connect the TOP 2-pin grey
connector and the middle 8-pin GREY
Power Cable
This harness has a self-contained charging
cable for the alternator and starter,
therefore the only cable needed is from the
battery to the starter power terminal. We
recommend using a 2-Gauge wire for the
MAIN power supply to the starter.
Fuse Box Power
The fuse box needs to be wired directly into
the battery, as in the factory connections.
Use wire ties to ensure the wire harness
does not come in contact with rotating or
hot engine parts.
A/C Option
When the A/C option is selected you will
receive a 3 pin connector wired from the
ECU, which connects to the GM A/C
Pressure Sensor. This pressure sensor
does NOT exist on the 240sx. We
recommend welding on a fitting on the
high-pressure A/C line, near the firewall
opening. Connect the 3-pin connector to
the standard GM sensor.
The second sub harness connects directly
to the LS1 A/C compressor. The ground
ring is connected to the front of the LHD
passenger side head. Last, the blue signal
wire is tapped into the factory 240sx A/C
signal wire on the US driver’s side.