We may earn a referral commission from some links on this page. It doesn't change your price or our recommendations.
Owning one · troubleshooting
Bow thruster not working? Find the cause before you call the yard
You push the joystick and get nothing, or it turns and the boat does not move. Most failures come down to a handful of causes. Find your symptom, then work down its checks. None of them need anything taken apart.
- Every check from a maker’s manual
- Nothing to take apart
- Won’t stop? Switch the main battery off first
- Check first The main switch › Then the battery voltage, then the fuses.
- Fuses to check 2 › One on the controller, one near the battery.
- Weak since the day it went in The cable › A long or thin run loses volts before the motor.
- Spins, but no push Shear pin › Or damaged blades. Both sit inside the tunnel.
- The one tool you need A voltmeter › All but the look inside the tunnel can be done afloat.
- Kinds of thruster covered 3 › Tunnel, external and retractable, each from its maker’s manual.
Find yours by symptom
- Nothing happens at all. Check the main switch, the battery voltage and the fuses, in that order. Then look for something jammed in the tunnel. No response
- It turns, but weakly. It has been run hard and is protecting itself, something is wrapped around the propeller, or the cable is too long or too thin. Weak thrust
- It spins, but the boat does not move. The motor is fine. A sheared pin or damaged blades inside the tunnel are the usual cause. No push
- The panel will not switch on. Usually a missed startup step, not a fault: the second press came too late, or the joystick was off center. The panel
- A light is flashing, or the panel beeps. One of the thruster’s own protections has tripped. Open your maker’s codes to see which one. Light codes
- It runs and will not stop. Switch the battery main switch off now, then find out why. Its own page
The checks follow a VETUS BOW PRO owner's manual, which says what causes what. Other makers do not always fail the same way, so a number on this page says whose it is. External units and retractables have their own sections, from their makers’ manuals.
At the stern. A stern tunnel thruster is the same kind of unit as a bow one, and 95 of the 140 tunnel models this site lists are sold for either end. So it is covered by the tunnel checks on this page. The units made only for the stern are external, from Max Power, Sideshift, Sleipner, Yacht Thruster and ezDrive, and the sections below on the other kinds cover the Sideshift and DockStar ones.
Before you open anything: the power
Check three things, in order. Each one rules out the one before it.
- Is the battery main switch on? It sounds obvious, and sometimes it is the answer. A switch left off after the last Lifting the boat out of the water on a travel lift or a trailer so work can be done below the waterline. It is billed separately from the job itself., or bumped by a knee, looks exactly like a real fault: total silence.
- Is the battery voltage in range? On VETUS's BOW PRO line the controller starts cutting power once a 12 volt system The drop in a battery’s voltage while a heavy load is drawing from it. The battery recovers when the load stops, but the motor only ever sees the sagged figure. to about 10.5 volts, and stops the thruster around 10. It runs again the moment the voltage recovers. On 24 volts the figures are 21 and about 20. For 48 volts the manual gives only the working range, 42.0 to 57.6 volts, and no stop figure.
- Has a fuse blown? There are usually two to check: the small control-circuit fuse on the controller, and the main supply fuse near the battery. Either one gives the same symptom from the joystick. The two fuses
It does not do anything at all
Say the joystick gets no response and the power light on the thruster's motor housing stays dark. The cause is one of the three checks above, or one more: an overload.
If something briefly jammed in the A tube bored straight through the hull below the waterline, with a propeller in the middle of it. It is the conventional thruster. Installing one is mostly a labor job rather than a hardware one., the motor's own protection may have shut it down. The light comes back on by itself once the controller has cooled, and the thruster works again.
Before you write it off as electrical, check whether the propeller turns freely by hand, with the battery switch off. A piece of wood or debris caught between the blade and the tunnel wall is a common mechanical cause. From the panel it looks exactly like a dead thruster.
Two fuses, two places. On VETUS's controllers, either of two fuses can be the reason. A small control-circuit fuse lives on the controller itself. It protects the low-current wiring that runs to the panel.
A larger main supply fuse sits near the battery and protects the whole thruster circuit. Either one blowing gives the same symptom from the joystick: nothing.
A replacement fuse has to match the original rating. A bigger one defeats the reason the fuse is there.
It turns, but weakly
A weak thruster is a different symptom from a silent one, and it points somewhere else. Three causes cover almost every case.
- It has been run hard. Bow thruster motors are not built to run continuously. VETUS rates its DC BOW PRO motors for about ten minutes of continuous use, or a similar total per hour, at full current. Run one past that and the thruster turns its own output down to protect the motor and controller from overheating. It does not trip and stop. It comes back to full strength once it cools.
- Something is wrapped around the propeller. Weed and fishing line are the usual suspects. A thruster A tube bored straight through the hull below the waterline, with a propeller in the middle of it. It is the conventional thruster. Installing one is mostly a labor job rather than a hardware one. collects both. The water inside it barely moves, and the boat almost never flushes it out on its own.
- The cable is too long or too thin for the draw. Suspect this one when the thruster has been weak since the day it went in. A thruster pulls hundreds of amps, and every foot of cable between the battery and the motor takes a little of the voltage. Less voltage at the motor means a slower motor and less push, cold or hot, from the first second. The usual layout invites it: the The batteries that run the boat’s lights, fridge and electronics, as distinct from the engine’s starting battery. They are built for a slow, steady draw. aft, the thruster at the bow, and a long cable run between them.
Check your own cable run. Put your cable size and run length into the wiring calculator. It works out how many volts the run loses, and sets that against The American Boat and Yacht Council, the body that writes the standards US boats are built and wired to. A surveyor or an insurer who asks whether wiring is to standard means ABYC’s.'s limits and the cutoffs above.
It turns fine, but nothing happens to the boat
This symptom means the motor is healthy and something between the motor and the water is not.
Most tunnel and A thruster that lives inside the hull and drops down through a hatch when you press the button, then pulls back up. It leaves no permanent hole in the water flow. thrusters use a A small, deliberately weak pin between the shaft and the propeller. If the propeller jams on a rope, the pin breaks instead of the gearbox, and it costs a few dollars to replace. on the propeller shaft. Hit something hard in the tunnel and the pin breaks. That pin is a cheap, replaceable part, and breaking it saves the gearbox behind it. A sheared pin lets the motor spin the shaft with nothing turning at the other end. From the panel, it looks and sounds normal.
Damaged propeller blades are the other common cause, from the same kind of debris that shears a pin. Both need a look inside the tunnel, which usually means a Lifting the boat out of the water on a travel lift or a trailer so work can be done below the waterline. It is billed separately from the job itself. or at least a diver.
Tell the yard on the phone that the motor runs and the bow does not move. That narrows the job to a pin or a propeller before anyone climbs aboard. The shear-pin page says which makers use one and what the manual says to do next.
The panel itself will not switch on
This one is almost never a fault. VETUS's panels are pressed twice, on purpose, within about six seconds of each other. The first press wakes the panel, and the second confirms it.
Two things stop the panel finishing its startup:
- missing that six-second window
- having the joystick off-center when you press the switch
Both look like a dead panel until you know what to check.
What the lights and beeps mean, maker by maker
A flashing light or a beep from the panel means one of the thruster’s own protections has stepped in. Each maker uses its own codes, so open the fold for your thruster and leave the others closed.
VETUSLight and tone codes
On VETUS’s system, the panel sounds a single warning tone and flashes its LED red the moment any of its own protections engage. That covers:
- the motor or controller running too hot
- current too high
- a short circuit
- battery voltage out of range
- the motor jammed
The tone and the color are the same whichever one triggered it. So the light tells you that something tripped, and not what. For that, go back to the power checks.
Once the condition clears, the panel confirms it with a different, shorter tone. The red LED goes out on its own, with no button press.
From the VETUS BOW PRO owner’s manual.
DockStarLight codes
The light is the LED in the on/off switch. Each pattern repeats every one and a half seconds. Press the switch to read the battery before you lower the unit.
| The LED | What it means |
|---|---|
| Dark | Off, or asleep. |
| One long glow | Switched on, battery low. Charge it. |
| A long flash, then one short blink | Switched on, under 25 percent charge. |
| A long flash, then two short blinks | Switched on, 25 to 50 percent. |
| A long flash, then three short blinks | Switched on, 50 to 75 percent. |
| A long flash, then four short blinks | Switched on, over 75 percent. |
| Fast, even blinking | Lowered all the way down the track and ready to run. |
| One to four short blinks, on the charger | Charging. The count is the charge: one under 25 percent, four at 75 to 100. |
| On, with one short gap | Nearly full, balancing the cells. |
| Steady on, on the charger | Charging complete. It stays on for two hours. |
| A short blink, a pause, then one to four short blinks | The charger was unplugged before it finished. The count after the pause is the charge. |
| Four blinks, each shorter than the last | Pairing mode, waiting for the remote. |
| Steady on, with a remote button held | Pairing done. |
From DockStar user manual, version 260305, LED Flashing Patterns (page 29) and pairing (page 24).
The motors are locked out until the unit is fully down on its track, so a unit that runs nothing usually shows a battery pattern, not the fast blinking. A pattern that is not in this table: DockStar asks for a twenty-second video of the LED and says not to use the unit until they have answered.
SideshiftLight and beep codes
The light sits at the receiver’s white connector.
| The light | What it means |
|---|---|
| No light | Check the 10 amp fuse on the receiver’s red wire. |
| A flash every two seconds, for the first two minutes | The pairing window. |
| A flash every seven seconds | Idle, waiting for a joystick. |
| A fast double flash every second | Over-voltage. The receiver wants 12 volts, so a 24 volt thruster needs a separate 12 volt feed to it. |
| Solid red | Paired and talking. |
| Fast beeps, then slow beeps (PT and HB models) | The leg is going down, then it is down. |
| Two beeps (PT and HB models) | The receiver has lost the actuator arm. Check the 6-pin connector, then call Sideshift. |
| One continuous beep (PT and HB models) | The arm is blocked or its linkage is bent, which is what driving with the thruster down does. Call Sideshift. |
SleipnerLight and screen codes
Sleipner uses different signals on different equipment. Open the one that matches your panel or your retractable. The round on/off panels on its tunnel thrusters (8950, 8955, 8960 and 8965) light their LED when on, and their manual lists no codes.
From Sleipner round control panels manual, document 3023 rev 14, 2025.
The 8700 touch panelFlash codes on the retractables’ panel
The panel has three small lights: green on the left, yellow between the two ON buttons, and red on the right. A fault makes two or all three of them flash at the same moment, a set number of times, then pause before it repeats. Note which lights flash, and count the flashes before the pause. Most of these faults make the thruster pull its leg back up by itself.
| Which lights flash together, and how many times | What it means | What to do |
|---|---|---|
| Yellow and green, once | The thruster is too hot. It retracts. | Turn the panel off and wait 20 minutes. |
| Yellow and green, twice | Low power. It retracts. | Turn the panel off and charge the batteries. |
| Yellow and green, three times | Something stopped the leg going down. It retracts. | Turn the panel off, slow down or move to deeper water, and try again. |
| Yellow and green, four times | The leg’s position sensor has failed. It retracts. | Check the sensor’s wiring and connection for a short or a break. |
| Yellow and green, five times | A short circuit on a solenoid output, port or starboard. It retracts. | Check the solenoid’s wiring and connection, and whether the solenoid itself is shorted. |
| Yellow and green, six times | The motor’s temperature sensor has failed. It retracts. | Check the sensor, its wiring and its connection. |
| Yellow and red, once | The actuator has lost power. The system shuts down. | Turn the panel off, check the actuator’s connections, and try again. |
| Yellow and red, twice | An internal fault in the thruster. It retracts. | Turn the main switch off at once, to save the main relays from overheating. It needs a Sleipner service center. |
| Yellow and red, three times | Something stopped the leg coming up. It tries three times, then stops. | Press both ON buttons to lower the leg, turn the main switch off, and clear whatever is in the way. |
| All three, once | The automatic main switch has lost power. | Check the power to the automatic main switch. |
| All three, twice | The automatic main switch’s fuse has blown. | Replace the fuse. On a new install, check its input and output are wired the right way round. |
| All three, three times | The automatic main switch is on manual override. | Pull the automatic main switch back up. |
| All three, four times | The panel cannot reach the thruster. | Turn the panel off, check the main switch, the fuse and the cables, and try again. |
From Sleipner 8700 control panel manual, document 2069 rev 5, 2023, page 8, on the panel’s product page.
The leg will not come up while the boat is going astern at speed. Trying it makes the yellow and red lights flash together three times. Slow down and press both ON buttons before you try OFF again.
The retractable’s control boxThe status light on the SR, SRP, ERL and ERV retractables
The control box beside the retractable unit has two lights next to its UP and DOWN buttons: a red one marked FAULT and a green one marked STATUS. They mean the same on every one of these models.
| The light | What it means |
|---|---|
| Red FAULT light, steady | A fault. It can be any of nine: the motor or the controller too hot, the controller not talking, a motor relay failure, low battery voltage, a failed position sensor, no power to the actuators, a failed retractable unit, or a temperature sensor wire broken. |
| Red FAULT light, blinking fast | A dip switch on the box is in a position that is not allowed. |
| Red FAULT light, a short flash every two seconds | The leg has not been calibrated, or was calibrated out of range. |
| Green STATUS light, steady | Normal running, or service mode with the leg worked by the UP and DOWN buttons. It also shows after the down position is set again. |
| Green STATUS light, flashing | No S-Link connection with the rest of the system. |
From Sleipner ERL130 to ERL210 manual, document 7241 rev 22, page 33 and the SR, SRP, ERL100 and ERV manuals, which print the same table.
A steady red FAULT light does not say which of the nine faults it is. Turn everything off, then work through the power checks above, and read the panel’s own code if it shows one.
The S-Link color screen panelsThe PJC panels show a fault code on the screen
Sleipner’s color touch-screen panels (the PJC range) print the fault on the screen as a code. Sleipner keeps the full list online in its Fault Code Navigator. Type in the code and it gives the meaning and the fix. It also links a downloadable list and a manual for older codes.
LewmarLight codes
The panel has one light that changes color. The tunnel and retractable panels use the same colors.
| The light | What it means |
|---|---|
| Steady green | The system is on. |
| Flashing green (retractables) | The leg is moving. |
| Amber | Low battery voltage. A warning only: it does not change the thrust. |
| Flashing red | The motor is too hot. It runs again, and the light turns green, once it cools. |
| Steady red | Fault mode. Press ON once to switch the system off. |
From Lewmar Gen 2 TT manual, 559231 Iss.3 (a dealer’s copy) and Lewmar retractable manual, ref 55110070 iss.4 (a dealer’s copy).
Three things put a Lewmar into fault mode. The first is thrusting one way for more than three minutes. The second is a joystick held to one side when the panel is switched on. The third, on a retractable, is a leg that does not finish its travel in the allowed time. The panel switches itself off after 15 minutes idle on a tunnel, 5 on a retractable.
Max PowerLight and beep codes
Max Power’s panels mostly talk in beeps. Each line says which units it applies to.
| What you see or hear | Which units | What it means |
|---|---|---|
| Beeping, with the green LED flashing | CT tunnels | The motor is too hot. You have about ten seconds of thrust left, then it shuts down until it cools. |
| One beep, then a second a few seconds later | CT tunnels | It is switching itself off after sitting idle. |
| Both joystick buttons flashing red | ECO proportional tunnels | Too hot. The controller first cut the power to 80 percent, then stopped. It will not switch on until it cools. |
| Both buttons blinking, and the light on the controller | ECO proportional tunnels | An error. Max Power’s app names it; the manual prints no list. Reset by pushing the joystick left for ten seconds. |
| The ON light flashing once a second | VIP retractables | The motor is too hot. About ten seconds of thrust are left. Raise the leg; it will not switch on again until it cools. |
| A short beep every half second, Up and Down lights flashing | VIP retractables | You let go of the button before the leg reached the end of its travel. |
| A short beep every three seconds | VIP retractables | The leg is down. |
| The Up light flashing, a beep every second, at switch-on | VIP retractables | The leg is not seen as up. Press Up until it is. |
| Every light flashing, with the alarm | Compact Retract | Manual mode, after the leg met resistance. Lower it until it double beeps, raise it until it double beeps, then switch off. |
| The lights flashing in turn, a short beep each second, then two long beeps | Compact Retract | Too hot. It retracts and switches off until the motor cools. |
From Max Power CT100/CT125 manual, July 2024 and Max Power ECO-PRO 90, 110 and 130 manual, version 4 and Max Power VIP 150 manual, 2025 and Max Power Compact Retract manual, 2026.
QuickLight and beep codes
Quick’s signals depend on the control fitted. Open the one that matches yours.
The TCD control panelPush-button and joystick panels for the BTQ tunnels
The panel has enable lights, which show it is switched on, and two direction lights: red for port and green for starboard. A fault that needs a reset is counted out on the enable lights, with a short sound on each flash. Switch the panel off and on again to clear it once the cause is fixed.
| What you see | What it means |
|---|---|
| Enable lights flash slowly, a sound as they go off | The supply has dropped below 10.5 volts. It clears itself when the voltage recovers. |
| The red and green direction lights flash together with the enable lights | About five minutes of continuous running. The panel locks out while the thruster cools. |
| Every light flashes quickly at switch-on | A memory fault in the panel. Call Quick’s service. |
| Enable lights flash once, then pause | An overload or short on the control line to the thruster. |
| Enable lights flash twice, then pause | A break in the control line to the thruster. |
| Enable lights flash three times, then pause | A fault reported by a BTR retractable. Read its light in the next fold. |
| Enable lights flash four or five times, then pause | A fault in a parallel/series switch or a TMS main switch, where one is fitted. |
From Quick TCD 1022 / TCD 1042 manual, REV004A (a dealer’s copy).
The BTR retractableThe red error light on the control unit
The BTR’s control unit has two lights. The red error light counts out a fault, then pauses before it repeats. A second, two-color light shows where the leg is: red closed, green open, orange somewhere between, flashing orange while it moves.
| The red error light flashes | What it means |
|---|---|
| Once, then a pause | The leg would not close after three tries. Something in the mechanism, the boat moving too fast, or the hatch binding. |
| Twice | The actuator’s fuse opened on more than 10 amps: a short or overload on its power line. |
| Three times | Both limit switches report at once. Check their wiring. |
| Four times | The actuator’s control line is broken. |
| Five times | The leg did not finish moving within fifteen seconds. |
| Six times | The dip switches are set wrong. |
| Seven times | The leg would not open. Same causes as one flash. |
| Eight times | A short or overload on the motor contactor line. |
| Nine times | The motor’s thermal cut-out has tripped, and the fix is to wait, or the contactor’s control line is broken. |
The proportional joystick (PCC TJ1)For the new QSY thrusters, and BTQ tunnels with the MSC speed box
This joystick has two separate lights: the enable light, which can show blue, orange, red or fuchsia, and the HOLD light, which flashes orange. For the serious faults both work at once. The HOLD light flashes once for a QSY thruster or twice for the MSC speed box, and the enable light flashes red a number of times that names the fault. A short sound plays with each flash.
| What you see | What it means |
|---|---|
| Enable light blue | The supply has dropped below 10.5 volts for more than a second. It clears above 11 volts. |
| HOLD and enable lights both flash orange, slowly | No thruster found on the network. Check the thruster has power and the network wiring. |
| HOLD and enable lights both flash orange, quickly | Two or more thrusters on one network. Connect only one. |
| Enable light flashes orange once, then pauses | Low supply voltage to the thruster. It clears when the voltage recovers. |
| Enable light flashes orange twice, then pauses | The motor is too hot. It clears when it cools. |
| Enable light flashes orange three times, then pauses | The control electronics are too hot. It clears when they cool. |
| Enable light flashes orange four, five or six times, then pauses | High input voltage, a blocked cooling fan, or no input voltage on the MSC box. The motor stops. See the MSC manual. |
| What you see | What it means |
|---|---|
| Enable light steady red, HOLD light dark | The motor drive lost its commands, and running stopped. Press the enable button to reset. |
| HOLD light flashes once. Enable light flashes red one to seven times | A motor management fault, and the motor stops. Call Quick’s service and give them the number of red flashes. |
| HOLD light flashes once. Enable light flashes red eight times | The motor windings are too hot. Let the motor cool. |
| HOLD light flashes once. Enable light flashes red nine times | The built-in inverter is too hot. Let it cool. |
| HOLD light flashes once. Enable light flashes red ten times | A short circuit or overload. The motor stops. |
| HOLD light flashes once. Enable light flashes red eleven times | The supply voltage is too high. Check the power source. |
| HOLD light flashes once. Enable light flashes red twelve times | The supply voltage is too low. Check the power source. |
| What you see | What it means |
|---|---|
| HOLD light flashes twice. Enable light flashes red eight times | A broken connection to the direction contactors. |
| HOLD light flashes twice. Enable light flashes red nine times | The MSC box’s temperature sensor has failed. |
| HOLD light flashes twice. Enable light flashes red ten or eleven times | An overload on the contactor output, or on the line switch output. |
| HOLD light flashes twice. Enable light flashes red twelve times | Both of the box’s cooling fans have stopped. |
| HOLD light flashes twice. Enable light flashes red thirteen times | A broken connection to the line switch. |
| HOLD light flashes twice. Enable light flashes red fourteen times | The thruster is drawing too little current. |
| HOLD light flashes twice. Enable light flashes red fifteen times | A short circuit or overload on the motor output. |
| What you see | What it means |
|---|---|
| Enable light flashes red, very fast or fast | A memory fault in the joystick. Do not use it. Call Quick’s service. |
| Enable light flashes very fast in fuchsia or blue | A lever calibration fault, or a setup fault in the joystick. Do not use it. Call Quick’s service. |
From Quick PCC TJ1 B00 manual, REV 001C, section 4, pages 37 to 39.
To clear a red-light fault, hold the enable button for at least three seconds. The light turns blue, the beep stops and the light goes out. If the fault comes back, the joystick shows it again.
Two makers print no codes. ezDrive’s installation guide has none, and we have found none for Yacht Thruster. For those, the checks above are the whole list.
Your kind of thruster: its own checks
Five kinds of unit have checks of their own in their makers’ manuals. Open yours. The others stay closed.
SideshiftIts own checklist, for a sealed external unit
A Sideshift has no tunnel to foul, and its motor is sealed. Its installation manual (Rev 3.1, November 2025) gives one order of checks for a unit that will not run, runs weakly, or whose joystick switches itself off after a few seconds:
- Battery switch first, then the joystick. The thruster’s battery switch has to be on before the joystick is powered up.
- The joystick’s blue light. Hold the power button for a second; a beep and a solid blue LED mean it is on. It switches itself off after twenty minutes unused.
- The voltage on the fuse holder. Sideshift’s fuse holder carries a display. Before you power the joystick it should read 12.6 volts on a 12 volt system, 25.2 on 24, by the manual’s operating page. If the display is dark, look at the A flat, bolt-down fuse made for heavy loads like a thruster or a windlass. It is built to carry a big overload for a while and open only on a short circuit. for a blown element, or check it with a meter.
- Load-test the batteries. The manual’s test is a burst of three to five seconds while you watch the display. The lowest reading must stay at or above 10.9 volts on a 12 volt system, 21.8 on 24, or the batteries may be due for replacement. Then check the cable gauge between battery and motor controller against the manual’s tables.
- The voltage keeps sagging? The charging system is the suspect, and after that the batteries themselves.
The receiver’s light, and the beeps on the retracting pontoon and houseboat models, are in Sideshift’s codes above.
If every check passes, the manual’s last line is that the motor may need replacing. The unit is sealed; there is nothing to open. Two run limits are worth knowing while you test. The first is the burst: the manual says 3 to 5 seconds, never more than 20 to 30, and the FAQ says 5 to 10 seconds with 10 to cool, never more than 30. The second is no more than five seconds with the propeller out of the water.
DockStarIts own fault table, for a unit with its own battery
A DockStar carries its own battery, so most of the checks above do not apply: there is no cable run, no battery bank and no main switch. Its user manual (v.260305, linked from the DockStar review) has a troubleshooting table, and it starts somewhere a tunnel owner would never think to look.
It will not run at all. The motors are locked out until the unit is fully lowered on its track; a sensor stops it running dry. Seat it at the bottom of the track, then read the LED: its flashing pattern says whether the unit is armed and how much battery it has. Below half charge, charge it. Then confirm the remote is paired and that the remote’s own coin cell (a CR2032, replaced yearly) is not flat.
It runs briefly, then fades. That is the battery. Read the charge from the LED pattern and charge fully. The manual asks for a full charge and balance after no more than ten minutes of total running.
It is hard to lower. Check the track is straight and undamaged, and that the track guides on the unit are all there, straight and aligned. Guides gripping too tightly can be lightly sanded on the back; the track and guides take a water-based silicone spray. A bent track means stop until it is repaired.
It vibrates. Take the propeller off and refit it turned through 180 degrees, and check the cap and blades for damage or debris.
It will not charge. Seat the plug firmly; the charger’s LED should go from green to red when it connects. No light at all points at the outlet or the charger’s own cord. Green that never turns red points at the supply: the charger wants a clean 110 to 120 volt, 60 hertz sine wave with 4 amps behind it.
A flashing pattern that is not in the manual’s table. DockStar asks for a twenty-second video of the LED and says not to use the unit until they have answered. Over-current protection is a self-resetting fuse inside the unit; there is nothing for an owner to replace.
Every LED pattern, battery and charging included, is in DockStar’s codes above.
Sleipner SX stern unitsThree faults that need a dealer
An SX stern unit runs off the boat’s batteries through a main switch and fuses, so the power checks above apply first. Sleipner’s user manual then adds three faults a dealer has to fix.
- It will not stop when you let go. Switch the main battery switch off. The manual says the control system is damaged and to call a Sleipner dealer.
- It only pushes one way. Switch the main switch off. A relay is damaged, and the manual sends you to a dealer.
- It runs in pulses. That is the controller’s own error response to a failed solenoid. Switch the main switch off and call a dealer.
From the Sleipner SX user manual, document 5924 rev 10, 2025, on the SX35 product page.
Max Power stern podsFour checks from its manual
A Max Power stern pod is wired like a tunnel unit, through an electronic control box and a relay. Its manual gives four checks before you call a dealer.
- The panel will not light. Check the 6-wire plug behind the joystick and the one on the control box, the breaker or switch on the boat’s DC panel, and the control box’s 8 amp fuse.
- The relay clicks, but the motor does not run. Check the motor’s fuse, the battery switch, and the batteries and their connections. The manual says only a qualified technician should check the relay contacts inside.
- The motor runs, but nothing happens. Check the propellers are on, look at the motor and drive leg, and clear anything in the propellers.
- It lacks power. Check the propellers, the battery size and charge, the connections, and the cable size against the manual’s table.
From the Max Power stern pod manual, troubleshooting guide.
Any retractableThe leg, the hatch and the actuator
Once the leg is down, a retractable is a tunnel thruster, and everything above about voltage, fuses, debris and shear pins applies. The leg adds its own parts: an A small electric motor and screw that pushes a part into position. On a retractable thruster it is what lowers the unit out of the hull and raises it again., a hatch, and a pair of A small switch that tells the controller a moving part has reached the end of its travel. It is how a retractable thruster knows it is fully down or fully up. A dirty or failed one stops the unit from running. that tell the controller where the leg is. It will not thrust until the switches say it is down, and most of a retractable’s own faults live there.
Lewmar’s retractable manual (ref 55110070) reads its panel light in five colors, listed in Lewmar’s codes above. For a leg that did not finish its travel, the manual says check the down switch, the wiring to the actuator, and the adjustment of the up and down switches. Its fault-finding table then runs:
Fuse keeps blowing: the wrong rating, or a jammed propeller loading the motor.
Poor thrust, or thrust one way only: at least 10 volts at the motor while running (21 on 24 volts), a clear tunnel, the propeller washers the right way round, Small carbon blocks inside a motor that press on the spinning part and carry the current into it. They wear down, they shed dust, and they are the usual reason an old thruster motor stops. and their springs seated, the D1 and D2 terminals tight.
Motor turns, no drive: a broken shear pin or broken blades. Stop running it.
Noisy and vibrating: the propeller touching the tunnel wall; on the 140 and 185, the hub height.
Quick’s BTR manual (rev 002A) counts faults out on a red error LED, from one flash to nine. They are in Quick’s codes above.
Both makers say the same thing about the hatch: if it does not close flush and the leg comes up hard, stop and look for the obstruction before you look for an electrical fault.
ezDrive and Yacht Thruster print no checklist of their own. For those, the checks above are the whole list.
When it is time to call someone
You can check everything above with the boat in the water and no tool beyond a voltmeter, except the look inside the tunnel. Two things push the job past that.
The first is a sheared drive pin or a damaged propeller. Both live inside the tunnel, and getting to them usually means a Lifting the boat out of the water on a travel lift or a trailer so work can be done below the waterline. It is billed separately from the job itself..
The second is an electrical fault that survives a fresh battery, a known-good fuse and a clean connection at the switch. That points at the wiring or the controller itself. It is slow going without a meter and the wiring diagram in hand.
If you are weighing a repair against a new install, see what a bow thruster costs installed. To sort the work you can do yourself from the work that belongs to a yard, read what is realistically a weekend job.
The failing thruster may have been undersized for the boat to begin with. If so, the thruster finder, our free tool that matches a thruster to your boat, will tell you what fits.