Furuno GP3-400-183-06 6m NMEA0183 Cable Assembly for GP340

The GP3-400-183-06 is the factory NMEA0183 cable assembly Furuno built for the GP340 GNSS receiver. It's six meters of cable, about 19.7 feet, terminated at the factory so the data connector matches the GP340's port exactly. No crimping at the helm, no guessing at a pinout diagram taped to the console. You plug it in and the receiver starts talking to the rest of your electronics.

Here's why that matters. NMEA0183 is a serial data standard, and it's fussy about wiring. Swap the transmit and receive lines, or get a cold crimp on one conductor, and the GP340 will look alive while sending nothing your plotter can read. We've chased that exact ghost on more than one install. A factory assembly takes that whole class of problem off the table, because the wire order and the connector are already correct for this receiver.

Six meters covers most boats. On a center console with the GP340 mounted under the leaning post or behind the dash, that's plenty of slack to route the cable cleanly and still leave a service loop. On a taller flybridge boat, where the receiver might sit a deck below the upper helm, six meters can come up short, so measure your run before you rig it in. If you need more reach, plan the extension carefully and keep every connection weatherproof.

Routing is where most NMEA0183 headaches start. Keep this cable away from engine harnesses, alternator leads, and any high-current DC runs. Electrical noise off a diesel or a hard-charging alternator can bleed into a data line and show up as dropped sentences or a jumpy position. Run it along a separate path where you can, and if you have to cross a power cable, cross it at a right angle instead of laying it alongside.

A couple of small things save you grief later. Don't over-tighten the connector. The wires inside an NMEA0183 plug are thin, and cranking the shell down hard can pinch or break a conductor. Snug is enough. And on any boat that pounds or vibrates, sailboat or powerboat, secure the cable with tie-wraps near the plug so vibration doesn't slowly back the connector loose over a season.

One thing to be clear about: this is a data cable, not a power cable and not an antenna. The GP340 is a GNSS receiver, and this assembly handles the NMEA0183 side of it, the serial output that other instruments listen to. If you're troubleshooting a GP340 that powers up but won't share a position with the rest of the helm, the data cable is one of the first things worth checking, and having the correct factory assembly on hand makes that a quick swap instead of an afternoon.

NMEA0183 has been the workhorse serial standard on recreational and commercial boats for decades, and plenty of working helms still run on it. It's simple, it's proven, and one talker like the GP340 can feed several listeners when it's wired right. If you're landing more than one instrument on this output, pay attention to how each listener is connected and terminate the run properly so you don't load the line down. Done cleanly, a single GP340 can hand its position off to an autopilot and a plotter at the same time without complaint.

This is the cable to reach for when you're commissioning a new GP340, replacing a data cable that got cut or corroded, or bringing a receiver back to life after a refit. It carries the GP340's position and navigation output to a chartplotter, an autopilot, or radar over standard NMEA0183. It's black, it's the correct length for the job, and it's the genuine Furuno part, so you're not gambling on a no-name cable to feed your navigation data. Before you power everything up the first time, take a minute to confirm the connections against the GP340's wiring notes. Get it right once and this cable will sit quietly behind the dash doing its job for years.