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4Harness Installation Tips
FOR AUTOMOTIVE APPLICATIONS OF MARINE MEFI HARNESS:
In order for cooling fans to function via Infinity Series 3 ECUcontrol, Pin J1-23 of the FACTORY
HARNESS must be moved to Pin J1-22. Please see pinout documentation for information regarding J1
connector.
Wiring Conventions and EMI
Some wire harness assemblies come pre-wired with all connectors, fuses, and relays needed to operate
an engine. Harnesses that include a PDC generally require extension/termination of the flying leads to
their appropriate devices, and additional sensors and other devices can be wired into the harness as
needed for the specific application. The following guidelines should be adhered to while completing the
required wiring.
A proper wiring job includes proper termination of the wire at the sensor. The wire terminal end must be
moisture tight where it plugs into the sensor and it must have strong, electrically sound terminals. The
preferred method of securing a wire to a terminal is to use a crimp terminal with NO solder. It is
important to use the proper crimping tool for sound terminal construction. Plastic terminal plugs must
have moisture tight seals. Inspect each plug to make sure the seals are in place. Di-electric grease can
be added in the terminal slots to further aid in corrosion resistance.
If a splice into a wire must be made and no solder-less terminals are available, then you must properly
solder the splice.
Noise can be a serious problem and can cause intermittent misfiring of the engine. Every precaution
should be taken to prevent interference to the ECU’s operation. Resistive plug leads are REQUIRED.
To eliminate or reduce the chance of EMI, wires that carry high current must run in twisted pairs. An
example of this would be the power leads froma multiple spark ignition system. These ignition systems
can carry up to 100 amps for a couple milliseconds at the time of discharge, which induces a strong
magnetic field in close proximity of the wires.
The routing of the wire loom is critical to EFI system performance and safety. The following safety
considerations should be made when installing the wire loom:
·
Heat protection: the loomshould be placed away from or insulated from sources of heat. The
obvious item(s) that should be avoided are the exhaust manifolds, EGRdelivery tubes, and
turbochargers. If it is absolutely necessary to route a wire in close proximity to any of these
items, then a suitable insulator must be used. Reflective foil insulators should be used on all
harness lengths that are routed in close proximity to extreme sources of heat.
·
Noise suppression: do not route wires near HT (High Tension) leads such as ignition wires from
a distributor or a CNP (Coil Near Plug) ignition system. For coil-on-plug ignition systems this is
not as critical.
·
Shielding of important signal input wires such as Crank Sensor input, Cam Sensor input, and
Knock Sensor input should be addressed when assembling a harness. VR (Variable
Reluctance) sensors, also known as MAGsensors, are 2 wire sensors that generate a voltage
as the frequency increases of the trigger wheel. These wires MUSTbe wired in a twisted pair
configuration with a shield. The shield should be terminated to chassis ground at ONE END of
the lead while the other end is left unterminated. Failure to shield these wires with proper shield
