Garmin FORCE® Pro Trolling Motor Transducer Replacement Instructions

Getting Started

⚠ WARNING Always disconnect the motor from the battery before handling or working with the propeller, propeller drive motor, electrical connections, or electronics enclosures to avoid serious injury or death.

⚠ CAUTION For the best possible performance and to avoid potential injury, damage to the device, or damage to your vessel, installation by a qualified marine installer is recommended.

When stowing or deploying the motor, be aware of the risk of entrapment or pinching from moving parts, which can result in personal injury.

This manual covers replacing the transducer on a Force Pro trolling motor. If you are upgrading a Force trolling motor with the GT56UHD-TR transducer, you should refer to the Transducer Replacement Instructions for the Force trolling motor on garmin.com/manuals/force_trolling_motor.

You should read these instructions completely before beginning this service, and make sure that you have the tools and skill set needed to complete it. If necessary, you should use a qualified marine installer to ensure proper service.

Tools Needed

• #2 and #3 Phillips screwdrivers
• 3 and 4 mm hex bits or drivers
• 4 mm ball-head hex bit or driver
  NOTE: A ball-head bit is highly recommended due to the angle of some screws.
• Torque wrench
• Medium-strength thread-locking compound, such as LOCTITE® 243™
• Canned compressed air or an air compressor

Device Overview

Diagram showing the overview of the trolling motor components: [1] Shaft cap, [2] Power and transducer cables, [3] Steering system, [4] Mount, [5] Depth-adjustment collar, [6] Shaft, [7] Propeller drive motor.

Disconnecting the Shaft Cables

1. Open the shaft cap (refer to "Opening the Shaft Cap", page 3).
2. Disconnect the cables in the shaft cap (refer to "Disconnecting the Cables", page 4).
3. Remove the transducer cable from the shaft cap (refer to "Removing the Transducer Cable", page 5).

Opening the Shaft Cap

⚠ WARNING Always disconnect the motor from the battery before opening the shaft cap. The power cables in the shaft cap may carry high current, and accidental discharge may cause serious injury or death.

1. Using a #2 Phillips screwdriver, remove the four screws that secure the lid of the shaft cap.
2. Carefully lift up the lid of the shaft cap to access the cable connectors inside.

NOTICE: There are two cables connected to the top of the shaft cap. Take care when opening the shaft cap to avoid damaging the cables or connectors.

Disconnecting the Cables

1. Take a picture or note the arrangement of the cables in the shaft cap, so you can reproduce it correctly when you reconnect the cables and close the shaft cap.
2. Unscrew and disconnect the GPS data connector [1]. Ensure the o-ring remains in place inside the connector.
3. Release the latch and pull the connectors apart to disconnect the motor data cable [2].

NOTICE: To avoid damaging the cable, pull only on the connector body. Do not pull on the wire itself.

4. Carefully cut off the zip ties that secure the cables to the sides of the shaft cap.
5. Slide the rubber sleeves [3] away from the connection points on the power cables.
6. Using a 2.5 mm hex bit or wrench, loosen the set screws that secure each power cable connection.
7. Disconnect the power cables.
8. Remove the rubber sleeves from the power cables and set them aside.

Removing the Transducer Cable

1. Using a #2 Phillips screwdriver and a 3 mm hex bit or wrench, remove the three cable clamps that secure the power cable and the transducer cable to the trolling motor mount.
2. If necessary, pull the transducer cable out of the channel in the trolling motor mount.
3. Remove the plastic cable clamps that secure the transducer cable to the coiled power cable. Keep these cable clamps in a safe place for reinstallation.
4. Push from the inside out to remove the square grommet [1] that holds the transducer cable [2] in the shaft cap.
5. Remove the grommet from the transducer cable. The grommet is split on one side for easy removal. Keep the grommet in a safe place for reinstallation.
6. Feed the transducer cable through the shaft cap from the outside in until it is no longer routed through the square hole.

Removing the Shaft

⚠ CAUTION You must make sure the motor is securely latched in the deployed position before you proceed with this service. Working on the motor while the latch is not securely engaged may cause the motor to shift, potentially leading to entrapment or pinching, which can result in personal injury.

1. Remove the shaft cap (refer to "Removing the Shaft Cap", page 6).
2. Remove the depth limiter (refer to "Removing the Depth Limiter", page 6).
3. While supporting the weight of the propeller drive motor, loosen the depth adjustment collar on the base of the steering servo.

NOTICE: We recommend having a second installer support the propeller drive motor while you loosen the depth adjustment collar. The shaft may suddenly slide down and out of the steering servo, potentially hitting the ground and causing damage to the propeller drive motor.

4. Slide the shaft down and out of the steering servo, taking care not to damage the skeg and transducer or snag the cables or connectors as you pull it through.

Removing the Shaft Cap

1. Take a picture or write down the number of times the coil cable wraps around the shaft. This is needed for correct reinstallation.
2. Using a #3 Phillips screwdriver, remove the 1/4-20 bolts [1], lock washers, and nuts [2] that secure the shaft cap to the shaft. Keep these parts for reinstallation.
3. Lift up the shaft cap to disconnect it from the shaft.
4. Pull the cables completely through the shaft cap, taking care to avoid damaging the cable connectors.

Removing the Depth Limiter

1. Remove the screws from each half of the depth limiter and pull the pieces away from the shaft.
2. Lift up to remove the bushings [1] from inside the steering system housing.

Removing the Existing Transducer

1. Remove the skeg and nose cone from the propeller drive motor (refer to "Removing the Skeg and Nose Cone", page 7).
2. Remove the propeller drive motor from the shaft (refer to "Removing the Propeller Drive Motor", page 8).
3. Remove the transducer from the nose cone (refer to "Removing the Transducer", page 10).

Removing the Skeg and Nose Cone

1. Using a 4 mm hex bit or wrench, remove the four screws that secure the skeg to the propeller drive motor.
2. Remove the skeg.
3. Using a 4 mm hex bit or wrench, remove the two screws that secure the front of the nose cone to the propeller drive motor.
4. Using a 3 mm hex bit or wrench, remove the single screw that secures the bottom of the nose cone to the propeller drive motor.

NOTE: Keep all screws and parts in a safe place, as they will be reused when reassembling the skeg and nose cone.

Removing the Propeller Drive Motor

NOTE: When removing the propeller drive motor, using a ball-head hex bit or wrench is highly recommended because of the angle needed to reach the head of the screws.

1. Using the tool [1] included in the transducer replacement kit, remove the recessed nut [2] that secures the transducer cable to the shaft.
2. Using a ball-head 4 mm hex bit or wrench, remove the screws [3] that secure the shaft base to the propeller drive motor. Dispose of these screws, washers, and O-rings; new parts are included with the kit.

Diagram showing the propeller drive motor being separated from the shaft base.

3. Straighten the cables at the top of the shaft, and slowly pull the propeller drive motor away from the shaft base until you can see the power and data cables [4] connected to the propeller drive motor.
4. Holding the cables only, slowly pull them out of the shaft, taking care that the cable connectors do not get caught on the top of the shaft.

NOTICE: When removing the propeller drive motor and pulling its cables out of the shaft, pull only on the cables themselves and do not let the cables support the weight of the motor. Pulling on the propeller drive motor or letting the cables support the weight of the motor may damage the cable connections inside the motor.

5. Pull the propeller drive motor cables completely out of the shaft and set the propeller drive motor aside.

Removing the Transducer

Before you can remove the transducer, you must remove the propeller drive motor (refer to "Removing the Propeller Drive Motor", page 8).

1. Carefully pull the transducer cable straight down [1] through the bottom of the shaft until it is completely removed from the shaft.
2. After pulling the transducer cable through the shaft, pull it through the hole in the front of the shaft base [2], along with the rubber cable gland and the recessed nut. Dispose of the cable gland and recessed nut; a new cable gland and recessed nut are provided in the transducer replacement kit.

Diagram showing the transducer cable being pulled down and out.

3. Using a 3 mm hex bit or driver, remove the screws that secure the transducer to the nose cone. Dispose of these screws, washers, and bushings; new parts are included with the kit.
4. Remove the transducer and neoprene pad from the nose cone. Dispose of the neoprene pad; a new pad is included with the kit.

Installing the Replacement Transducer

After you remove the existing transducer, perform these actions to install the replacement transducer:

1. Install the new transducer in the nose cone (refer to "Installing the Transducer", page 11).
2. Install the propeller drive motor on the shaft (refer to "Installing the Propeller Drive Motor", page 12).
3. Install the nose cone and skeg on the propeller drive motor (refer to "Installing the Nose Cone and Skeg", page 14).

Installing the Transducer

NOTICE: You must use the new screws and seals provided with the transducer replacement kit. Reusing the original screws or seals may lead to product damage.

1. Place the new neoprene pad on the new transducer. The kit includes pads for different transducer sizes; select the one that fits.
2. Using a 3 mm hex bit or wrench and the new screws and bushings from the kit, secure the replacement transducer to the nose cone.
3. Place the 25 mm (1 in.) O-ring on the recessed nut in the transducer replacement kit.

Installing the Propeller Drive Motor

Before you can install the propeller drive motor, you must install the new transducer and route the transducer cable through the shaft (refer to "Installing the Transducer", page 11).

1. Remove the large 78 mm (3 in.) O-ring on the shaft base and discard it.
2. Using the packet included in the transducer replacement kit, apply grease to the new 78 mm (3 in.) O-ring.
3. Place the new 78 mm (3 in.) O-ring in the groove on the shaft base.
4. Using canned compressed air or an air compressor, blow out any dirt or debris in the four threaded holes on the top of the propeller drive motor.
5. Apply a medium-strength thread-locking compound such as LOCTITE® 243™ to the threads in the four threaded holes on the top of the propeller drive motor.

NOTICE: Thread-locking compound is required in these holes to maintain a tight connection between the shaft base and the propeller drive motor. Failure to use thread-locking compound can lead to water ingress and damage to the motor.

6. Remove the 36 mm (17/16 in.) O-ring from the top of the propeller drive motor and discard it.
7. Thread the cables from the propeller drive motor through the new 36 mm (17/16 in.) O-ring in the transducer replacement kit.
8. Using the packet included in the transducer replacement kit, apply grease to the new 36 mm (17/16 in.) O-ring.
9. Place the new 36 mm (17/16 in.) O-ring in the groove on the top of the propeller drive motor.
10. If the power and data cables from the propeller drive motor are not already aligned and bundled, straighten, align, and bundle them with tape. If the cables are not straight and aligned, they may not feed through the shaft smoothly.
11. Feed the power and data cables from the propeller drive motor up through the shaft until they emerge from the top.
12. Gently pull the ends of the power and data cables as you feed them the rest of the way through the shaft.

NOTICE: When feeding the cables, you must pull on the cable and not on the cable connectors. The data cable connector is fragile and may break if you pull on the connector.

13. Prepare the four bolts that came with the transducer replacement kit by placing a washer and a 4.75 mm (3/16 in.) O-ring on each one.
14. Using the grease packet included in the transducer replacement kit, apply grease to the 4.75 mm (3/16 in.) O-ring on each bolt. Avoid getting grease on the bolt threads.
15. REMEMBER: If you did not previously apply thread-locking compound in the four mounting holes for these bolts, you must apply it before installing these bolts.
16. Using a ball-head 4 mm hex bit or wrench, thread all four of the prepared bolts approximately halfway to make sure that the shaft base and the propeller drive motor are properly aligned.
17. With the shaft base and the propeller drive motor properly aligned, lightly tighten all four bolts by hand.
18. Using a torque wrench, tighten all four bolts to 4 N-m (35 lbf-in).

Installing the Nose Cone and Skeg

Before you can install the nose cone and skeg, you must install the propeller drive motor on the shaft base (refer to "Installing the Propeller Drive Motor", page 12).

1. From the transducer replacement kit, select the cable gland that fits your transducer cable: For a 4-pin transducer, select the cable gland with the smaller hole. For an 8- or 12-pin transducer, select the cable gland with the larger hole. NOTE: A cable gland without a hole is provided if you are not installing a transducer or not routing the transducer cable through the shaft.
2. Measure 20 cm (8 in.) from the point the transducer cable enters the transducer, and mark the transducer cable using a permanent marker.
3. Using the packet included in the transducer replacement kit, apply grease completely to all surfaces of the cable gland you selected.
4. Place the cable gland [1] at the marked location on the transducer cable.
5. While keeping the cable gland aligned with the mark on the transducer cable, gently pull the excess cable through the top of the shaft until the cable gland fits into the hole on the shaft base.
6. Using the packet included in the transducer replacement kit, apply grease to the 25 mm (1 in.) O-ring on the recessed nut [2] on the transducer cable.
7. Place the recessed nut into the hole on the shaft base, and tighten it using the included tool.
8. Tighten the recessed nut until it stops.
9. Place the nose cone onto the propeller drive motor.
10. Using a 4 mm hex bit or wrench, secure the front of the nose cone to the propeller drive motor using the two existing screws.
11. Using a 3 mm hex bit or wrench, secure the bottom of the nose cone to the propeller drive motor using the existing screw.
12. Using a 4 mm hex bit or wrench, secure the skeg to the bottom of the propeller drive motor using the four existing screws.

Reinstalling the Shaft

NOTE: We recommend having a second installer available to support the weight of the propeller drive motor while you feed the shaft through the steering servo housing.

1. Feed the transducer cable up through the steering servo housing.
2. Insert the shaft into the bottom of the steering servo housing, guiding the power and data connectors into the steering servo housing to prevent snagging the cables or connectors. NOTE: The shaft fits in the steering servo housing only in a certain orientation. If you encounter any resistance, remove the shaft, rotate it a few degrees, and try again. When it is in the correct orientation, the shaft will slide into the steering servo easily.
3. Push the shaft up the steering servo to a comfortable height for you to access the top of the shaft, and tighten the depth adjustment collar on the base of the steering servo housing.
4. Place the keyed bushing over the keyed side of the shaft, and slide it down until its lip rests on the servo housing. NOTE: The keyed bushing fits in the steering servo only in a certain orientation. While someone supports the weight of the propeller drive motor on the bottom of the shaft, you can loosen the depth adjustment collar and rotate the shaft and bushing to match the position of the notch in the steering servo housing.
5. Install the smooth bushing over the other side of the shaft and slide it down until its lip rests on the steering servo housing.
6. Place both halves of the depth limiter around the shaft so that one half fits over the key on the shaft [1], and both halves overlap the top of the steering servo housing [2].
7. Using a #2 Phillips screwdriver, install the 3 mm pan head screws to secure both halves of the depth limiter together. When the depth limiter is installed properly, it rotates with the shaft and cannot slide up the shaft.
8. Reinstall the shaft cap (refer to "Installing the Shaft Cap", page 17).

Installing the Shaft Cap

1. Insert the rubber wedge [1] into the bottom of the shaft cap. NOTE: The rubber wedge fits in the shaft cap in one orientation only. Examine the shape of the inside of the shaft cap and the shape of the rubber wedge to determine the correct fit.
2. Pull the cables from the shaft completely through the shaft cap.
3. Place the shaft cap on the shaft, making sure the coil cable wraps around the shaft the same number of times it did before you removed the shaft cap.

NOTICE: Ensure the coil cable wraps around the shaft the same number of times it did before you removed the shaft cap, to prevent unnecessary wear that may lead to a premature failure of the coil cable.

NOTE: Check the orientation of the shaft cap relative to the orientation of the propeller drive motor. The cables exiting the shaft cap must be on the same side as the propeller, so that the arrow on the shaft cap cover will point forward, relative to the propeller thrust.

4. Push the shaft cap down until the bolt holes on the shaft cap align with the grooves [2] on the shaft.
5. Apply a medium-strength thread-locking compound such as LOCTITE® 243™ to the ends of the 1/4-20 bolts.
6. Install the 1/4-20 bolts and split washers into the bottom of the shaft cap. NOTE: The bolts should slide all the way through the bottom of the shaft cap easily. If you encounter any resistance, rotate the shaft cap from side to side while pushing down on it until it is seated correctly and you can easily insert the bolts all the way through.
7. Using a #3 Phillips bit or screwdriver, secure the bolts to the nuts and lock the shaft cap in place. NOTE: The holes on one side of the shaft cap are shaped to hold the nut in place while you drive the screws from the other side.

Reconnecting the Shaft Cables

1. Install the transducer cable in the shaft cap (refer to "Reinstalling the Transducer Cable", page 18).
2. Connect the cables in the shaft cap (refer to "Reconnecting the Cables", page 19).
3. Close the shaft cap (refer to "Closing the Shaft Cap", page 19).

Reinstalling the Transducer Cable

1. Feed the transducer cable [1] completely through the square hole in the shaft cap.
2. Install the grommet [2] on the transducer cable. The grommet is split on one side for easy installation.
3. Push from the outside to secure the square grommet in the shaft cap.
4. Route the transducer cable alongside the coil cable, using the cable clamps to hold the cables together.
5. Route the transducer cable through the mount base alongside the coil cable, using the cable clamps to secure the cables to the base.
6. Route the transducer cable to the chartplotter and connect it.

Reconnecting the Cables

1. Add dielectric grease to the connectors on the GPS data cable [1], the motor data cable [2], and the motor power cables [3].
2. Place the rubber sleeves on the power cables from the shaft, so that you can later slip them over the power cable connections.
3. Reconnect the power cables and, using a 2.5 mm hex bit or wrench, tighten the set screws.
4. Slip the rubber sleeves over the power cable connections.
5. Secure the power cables to the sides of the shaft cap using cable ties, following the arrangement you noted before cutting the original cable ties.
6. Reconnect the GPS data cable to the connector on the shaft cap cover, and tighten the collar.
7. Reconnect the motor data cable, aligning the connectors so that the latch is engaged and the connection is secure.

Closing the Shaft Cap

1. Place the lid on the shaft cap.

NOTICE: Ensure the cables are routed away from pinch points before securing the shaft cap lid to avoid damaging the cables.

2. Using a #2 Phillips bit or screwdriver, install the four screws you removed previously to secure the lid of the shaft cap.

Appendix

GT56UHD-TR Transducer Specifications

Contact Information

Manufacturer: Taiwan International Aviation Electronics Co., Ltd.

Distributor: Shanghai Garmin Aviation Electronics Management Co., Ltd.

Address: 391 Gui Ping Road, Xuhui District, Shanghai (Xin Cao He Jing International Business Center, Block A, Floor 37)

Phone: 021-60737675

Customer Service Hotline: 400-819-1899

¹ The device withstands incidental exposure to water of up to 1 m for up to 30 min. For more information, go to www.garmin.com/waterrating.

² Dependent upon water salinity, bottom type, and other water conditions.

Substance Declaration

This table declares the presence of hazardous substances in components, based on SJ/T11364 standard.

○: Indicates that all homogeneous materials in this component contain the hazardous substance below the limit specified in GB/T26572.

X: Indicates that at least one homogeneous material in this component contains the hazardous substance above the limit specified in GB/T26572.

* This product manual provides detailed explanations of the product's environmental warranty period and special markings.

© 2025 Garmin Ltd. or its subsidiaries. Garmin, the Garmin logo, and Force are trademarks of Garmin Ltd. or its subsidiaries, registered in the USA and other countries. These trademarks may not be used without the express permission of Garmin. LOCTITE® is a trademark of Henkel Corporation in the U.S. and elsewhere.

GT56 Transducer (for Force Pro Trolling Motor)