Garmin GPS 400W User Manual (English)

Other manuals for Garmin GPS 400W

Questions and Answers:

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Katelyn GillespieAug 29, 2025
What to do if Garmin 400W Series GPS unit does not transmit?
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  Kristina MayAug 29, 2025
  If your 400W Series unit isn't transmitting, consider these potential causes: * PTT input not being pulled low: Verify that the PTT (mic key) input is pulled low for transmit. * No transmit power to the COM: Ensure power input is connected to the COM 25-pin connector P4002 11 and 12 and ground to P4002 21 and 22. * Low input voltage: Increase the input supply voltage to >12 VDC (>24VDC for 420 AW and 430AW models).
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Jerry PierceAug 25, 2025
How to fix a Garmin GPS 400W Series unit that does not power on?
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  Samantha NixonAug 25, 2025
  If your Garmin GPS 400W Series unit isn't powering on, the issue might be a lack of power to the main connector P4001. Ensure power is connected to the main 78-pin connector P4001, pins 19 and 20, and ground to P4001, pins 77 and 78. Also, check the circuit breakers and the main avionics switch.
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Jeff PughAug 25, 2025
What to do if my Garmin GPS 400W Series unit does not compute a position?
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  williamwatsonAug 26, 2025
  If your Garmin GPS 400W Series unit isn't computing a position, it could be due to not receiving signals. Check the GPS antenna connections and ensure the aircraft is clear of obstructions like hangars, buildings, or trees. Alternatively, the unit may need to complete its cycle, so wait 20 minutes.
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Jonathon MaloneAug 26, 2025
Why do Garmin GPS signal levels drop when avionics are turned on?
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  Carol Wilson MDAug 26, 2025
  If the GPS signal levels drop when avionics are turned on, it's likely due to noise interference from other avionics. To resolve this, turn off all avionics, then turn them on one at a time to identify the source of the interference. Route the GPS cable and position the GPS antenna away from these interference sources.
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Karen TaylorAug 26, 2025
How to improve low GPS signal levels on my Garmin?
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  stephen40Aug 26, 2025
  Very low GPS signal levels can be caused by a few things. First, check the GPS antenna installation, connections, and cable routing, ensuring the antenna is mounted on top of the aircraft. Also, make sure the aircraft is clear of hangars, buildings, trees, etc., which could be shading the antenna from satellites. Finally, RF interference at 1575.42 MHz from VHF COM can be a factor; try moving the GPS antenna further from the COM antenna, adding a 1575.42 MHz notch filter in the COM coax, fixing or replacing the COM, or disconnecting the ELT antenna coax to check for possible re-radiation.
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aarcherAug 27, 2025
What to do if my Garmin 400W Series GPS unit does not transmit?
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  barbaravasquezAug 27, 2025
  If the 400W Series unit doesn't transmit, it could be because the PTT input isn't being pulled low; check that the PTT (mic key) input is pulled low for transmit. Another reason could be no transmit power to the COM; ensure the power input is connected to the COM 25-pin connector P4002 11 and 12 and ground to P4002 21 and 22. The input voltage might also be too low; increase the input supply voltage to >12 VDC (>24VDC for 420 AW and 430AW models).
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Steven TapiaAug 27, 2025
Why does my Garmin 400W GPS keep 'searching the sky'?
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  Heidi HendrixAug 27, 2025
  The unit is actively searching for GPS satellites. Allow up to 20 minutes for the unit to complete its cycle or until your current position is located.
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Jason HorneAug 27, 2025
What to do if Garmin GPS signal levels drop when avionics are turned on?
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  jacobssamanthaAug 27, 2025
  If the GPS signal levels drop when you turn on your avionics, it's likely due to noise interference from other avionics. To resolve this, turn off all avionics and then turn them on one at a time to identify the source of the interference. Also, try routing the GPS cable and positioning the GPS antenna away from potential interference sources.
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Bailey JohnsonAug 28, 2025
What to do if Garmin 400W signal levels are very low?
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  Jamie HollowayAug 28, 2025
  Low GPS signal levels can stem from several factors: * Improper antenna installation or coax routing: Ensure the GPS antenna is correctly installed, with proper connections and cable routing. The antenna should be mounted on top of the aircraft. * Antenna shaded from satellites: Make sure the aircraft is in an open area, away from hangars, buildings, and trees. * RF interference: If there's RF interference at 1575.42 MHz from VHF COM, try moving the GPS antenna further from the COM antenna, adding a 1575.42 MHz notch filter in the COM coax, fixing or replacing the COM, or disconnecting the ELT antenna coax to check for possible re-radiation.
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Kelly AlexanderAug 28, 2025
Why Garmin 400W Series GPS unit does not compute a position?
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  lauraserranoAug 28, 2025
  If your 400W Series unit isn't computing a position, there could be a few reasons: * Not receiving signals: Check the GPS antenna connections and ensure the aircraft is clear of obstructions like hangars, buildings, and trees. * Unit cycling: Wait 20 minutes for the unit to complete its cycle.