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Garmin GSD 25 Sonar Module wiring diagram

Name: Garmin GSD 25 Sonar Module
Brand: Garmin

See the Garmin GSD 25 Sonar Module connection points and wiring example. Open the diagram in Crimp to add your equipment and plan the cables between them.

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Open this example as a new project. Use your own parts and cable lengths to make the plan yours.

Cable sizing for this example

Use the diagram as a starting point for your installation. Replace the example equipment and cable lengths with your own, and check the connections against your exact model's instructions.

3 m one way

12 V system

Wire: 1.5 mm² · 16 AWG
Example fuse: 4 A
Design current: 2.3 A
Voltage drop: 1.3%

Sized against ABYC E-11. The design current is the part's continuous draw. The length is one way; voltage drop includes an equal-length return.

Run-length and manufacturer assumptions

The editable example uses 3.048 m (10 ft) runs unless a shorter run is stated. Metric overviews round these to 3 m. Adapt the parts and lengths to your installation before choosing cable and protection.

This supply example retains the manufacturer's 4 A fuse. Follow the complete installation notes for connector polarity, mounting, controls and commissioning; verify the actual cable route and equipment revision. Manufacturer installation manual

Show sizes in AWG

Wiring diagram

How the GSD 25 is wired.

Open this example in Crimp to use your own parts and cable lengths. Review the assumptions and installation notes as you adapt the circuit.

Garmin GSD 25 Sonar Module wiring example with 3 components: House bank, Fused DC distribution, GSD 25. 4 cable connections. Crossings are not junctions.Red = positive · dark = return · dashed = signal. Cable labels are example values; use the equipment instructions and actual installation lengths.Scroll sideways to inspect all components and connections.

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Installation notes

Connections and installation requirements.

Guidance for this model, with sources linked beside the relevant advice.

Verified against the manufacturer's documentation (rev. 190-01833-02_0A, December 2014), checked 2026-10-01. Manufacturer documentation →

A sonar processor with its own power feed

The GSD 25 supplies sonar data to a compatible Garmin chartplotter over Garmin Marine Network. It requires a compatible transducer and a separate power connection. The network cable is not a substitute for the DC cable. The manual lists 27 W maximum electrical input; 27 W / 12 V gives the catalog’s 2.25 A nominal planning value. Actual input current depends on supply voltage and operation. The 1 kW RMS transmit specification describes sonar capability, not continuous DC input.

Preserve the factory fuse and connectors

The supply range is 10–35 V DC, covering nominal 12/24 V systems. Retain the supplied 4 A inline fuse holder. Connect the power cable’s positive and negative leads to the protected DC supply and negative return, checking the harness markings before energizing. Align each plug’s notch before tightening its locking ring; a correctly aligned plug should not require force. Cable extensions need their own length and voltage-drop check because this short guide does not publish a universal extension gauge.

Leave room for cooling and transducer cabling

Install where the enclosure cannot be submerged, with ventilation and visible status LEDs. Its IPX7 specification is not permission to put it in a routinely flooded bilge. Allow connector access and use supported Garmin transducer extensions when necessary. A cable-routing grommet does not by itself seal a deck or bulkhead penetration; apply suitable marine sealing where weatherproofing is needed.

Check discovery before interpreting the picture

Connect the network cable directly to the chartplotter or through a supported GMS 10 expander. After the chartplotter is turned on, a slow green blink indicates connection and normal operation. A slow red blink points to missing chartplotter communication; check network connections before replacing the sounder. Rapid red sequences indicate an error reported on the display; correct it and fully disconnect/reconnect supply as instructed. Verify transducer selection and plausible depth in known water after communication works.

Manual and scope

Garmin installation manual, 190-01833-02_0A, December 2014; pp. 1–2, including connections, blink codes and the specification table. The original PDF is retained in the marine source ledger. The drawing represents the identified electrical interfaces; it does not simulate the equipment’s mechanical performance, radio signals or fluid system. Unpublished connector ampacity and startup current remain unspecified.

Build it out

Connect it to the rest of your system.

Add GSD 25 to your diagram, then connect your batteries, chargers and loads. Crimp calculates cable sizes and checks the connections as you draw.

Every cable you draw there is sized against ABYC E-11, from the same tables as the reference on this page.

Technical reference

Specifications, terminals and supporting parts.

Check the model, ratings and connection points against your own unit before choosing installation hardware.

Catalog specification

Nominal voltage: 12 V
Compatible systems: 12 V / 24 V
Rated power: 27 W
Continuous draw: 2.3 A

Supporting parts

6.1 m total of 1.5 mm² (16 AWG) marine cable
Terminations for 1.5 mm² cable, matched to the equipment's screw terminals, leads or studs
4 A fuse and holder on the positive run
Heat-shrink, strain relief and terminal boots sized to the cable

Check stud sizes, fuse type, run length and how warm the space gets against the gear you actually have before you order.

Terminal map

Catalog connection points, current direction and planning limits. Check the manufacturer's pinout and connector ratings before installation.

TerminalPolarityRoleLimit

pos

positive · input

positiveinput—

−

neg

negative · input

negativeinput—

Marine Network

network

signal · bidi

signalbidi—

Transducer

transducer

signal · bidi

signalbidi—

A dash means a current rating is not specified here.

Method & provenance

Where the specifications and sizing come from.

Manufacturer specifications describe the equipment. Crimp calculates cable results from the circuit and assumptions you enter.

From the maker

What the catalog says

Manufacturer, model, ratings and which terminal does what come from the catalog. A newer revision, or the nameplate on the unit in your hand, can say something different — when it does, the nameplate wins.

ABYC E-11

What Crimp worked out

Sized against ABYC E-11. Boats built to UK or EU rules answer to ISO 13297 — check these figures against it before you build. The run length and the current above are what drive the result. Crimp doesn't know how warm your space gets; draw the cable inside an engine-bay zone on the canvas and it sizes for the heat.

Read how the sizing works

Next step

Plan your installation with GSD 25.

Open this example as a new project. Add your equipment and cable lengths, then review the sizing and checks for your setup.