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Garmin GSD 25 Sonar Module wiring diagram
Black-box sonar module with its own 10–35 V supply, 27 W maximum input and 4 A inline fuse. The 1 kW sonar transmit rating is acoustic-system output capability, not a 1 kW battery load. Garmin Marine Network and transducer ports do not supply generic DC loads.
- Nominal voltage
- 12 V
- Compatible systems
- 12 V / 24 V
- Rated power
- 27 W
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.
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
Edit this wiring exampleCable 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
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.
Installation notes
Before you install.
Open a question for model-specific guidance and sources.
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.
Technical reference
Specifications and terminal map.
Check the model, ratings and connection points against your own unit before choosing installation hardware.
Catalog specification
Black-box sonar module with its own 10–35 V supply, 27 W maximum input and 4 A inline fuse. The 1 kW sonar transmit rating is acoustic-system output capability, not a 1 kW battery load. Garmin Marine Network and transducer ports do not supply generic DC loads.
- Nominal voltage
- 12 V
- Compatible systems
- 12 V / 24 V
- Rated power
- 27 W
- Continuous draw
- 2.3 A
Terminal map
Catalog connection points, current direction and planning limits. Check the manufacturer's pinout and connector ratings before installation.
+
positive · input
−
negative · input
Marine Network
signal · bidi
Transducer
signal · bidi
A dash means a current rating is not specified here.
Sources and sizing method
Equipment specifications. Model details, ratings and terminal roles come from the catalog. Check your unit’s label and current manufacturer documentation for its exact revision.
Example sizing. Sized against ABYC E-11. Boats built to UK or EU rules answer to ISO 13297 — check these figures against it before you build. Results use the example current and run length shown above. Set your actual equipment, lengths and installation conditions in Crimp before choosing hardware.
Read how the sizing worksNext step
Plan your installation with GSD 25.
Open this example as a new project, or add this component to your existing diagram. Use your equipment and cable lengths to review the sizing.
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