Overview

The MotorGuide 8M4004178 is an HD+ sonar adapter cable that connects a Tour or Tour Pro HD+ trolling motor to a Garmin fishfinder that uses an 8-pin transducer port. It carries traditional 83/200 kHz 2D sonar and 455/800 kHz high-definition down-looking sonar signals so you can read bottom and structure directly under the trolling motor.

This is the clean way to use the trolling motor’s built-in sonar without adding an external transducer to the bracket. It is meant for HD+ enabled motors and it is not compatible with Xi Series motors.

Key features

• Connects MotorGuide Tour and Tour Pro HD+ sonar output to a Garmin 8-pin transducer port
• Passes 83/200 kHz 2D sonar and 455/800 kHz high-definition down-looking sonar signals from the trolling motor
• Compatible with Garmin GPSMAP and echoMAP series that use the Garmin 8-pin transducer connector
• Garmin SV models that use a 12-pin sounder connection require Garmin 8-pin transducer to 12-pin Sounder Adapter Cable with XID (010-12122-10), sold separately
• Not compatible with Xi Series motors

Compatibility and fit

Use this cable only when you have a MotorGuide Tour or Tour Pro that is HD+ enabled and you want to plug that sonar into a Garmin unit with an 8-pin transducer input. If your Garmin unit does not have an 8-pin transducer port, confirm what adapter your display needs before ordering.

Installation and setup

Connect the motor end to the HD+ sonar lead from the trolling motor, then connect the Garmin end to the display’s 8-pin transducer port. Route the cable with a gentle drip loop and secure it so it cannot rub on the shaft, hinge points, or steering cables when stowing and deploying.

For the cleanest sonar picture, keep sonar cabling separated from high-current trolling motor power wiring where possible, and use strain relief at the head unit so vibration and trailering do not pull on the connector.

Use cases on board

This is a good match for bow-mount setups where the angler wants sonar that tracks exactly where the trolling motor points, especially on bass boats and multi-species rigs that run Garmin electronics at the bow. It also helps on boats where you want fewer exposed transducer mounts and a simpler rigging layout.