20 Most Recent Garmin GPSMAP 178C GPS Receiver Questions & Answers

I have the same problem. Did you ever figure out why it was not loading? There are no software adjustments to be made. Just plug in the card and wait. It says its reading the card, but never goes any further. Let it 'read the card' for hours with no luck. Help!!!

Garmin GPSMAP... | Answered on Mar 26, 2013


first, reset the GPS. Check the back side of the GPS, on the bottom right there is a reset button, hit it and it should reset.

If it doesn't reset, then you should update the GPS. Updating helps to put the GPS back to order.

1. Plug one end of the USB cable into your GPS and the other end into your desktop or laptop computer. The GPS device will load the appropriate driver automatically, and a message on your GPS tells you that it is connected to your computer via USB.
2. Open your Internet browser of choice and type in the following web addres: "http://www8.garmin.com/support/collection.jsp?product=999-99999-27 "
3. Download the appropriate version of the software for your computer (Windows or Apple) and Install the WebUpdater by following the wizard (accept defaults).
4. Click "Start," "Programs," "Garmin" and " WebUpdater" to update your firmware and your maps. Periodically check and make sure your software is current.

or click: https://www8.garmin.com/support/collection.jsp?product=010-00340-00

If non of the above seems to solve the problem, then there is a problem with antenna. The antenna maybe defective or not contacting very well. As a result of this, there won't be signal and the Gps won't be able to find satellites because of little or no signal.

Perform the above task and give me feedback so that I would know if you need more help.


Garmin GPSMAP... | Answered on Aug 10, 2011

Hello Steven,

I can help out with the manual for your 178c Garmin, but as for being lost on the water, that is all on you :) Click on the link to download your manual.

Garmin has, if memory serves, discontinued your 178 in the last few months, accessories are likely still available for it in retail channels. If there is anything that you would like to have, consider getting them now, while still available.

Garmin GPSMAP... | Answered on Aug 31, 2010


Sounds very much like the wiring plug connections in the back, always overlooked but so important that connections are tight and contacting.

Garmin GPSMAP... | Answered on Aug 13, 2009


Does your unit have an external aerial as shown in the pic, If so double check the connection from the aerial into back of the fishfinder, lube with water proof grease (Non-conductive)

You do not say whether it has worked before.

Also need to know where it is located on boat, it must have a view of sky overhead (If internal antennae)

Ext antennae must also be in view of sky, not under "solid" cover.

Garmin GPSMAP... | Answered on Aug 13, 2009

If unit is as per pic I assume it has external antennae. Ensure the multi pin plug is secure in the rear of the unit and also use a fully charged 12 volt battery, Has it been working before?? Usually a rear plug problem. How old is unit. Just had a another thought, check that the polarity is correct, ie pos wire to RED (Pos) on battery. Very polarity sensitive.

Cheers cbacer

Garmin GPSMAP... | Answered on Aug 13, 2009

hey on the back side of it on the bottom right there is a reset button hit it and that possilble can be the problem if not you may have it in a bad spot on your dash

Garmin GPSMAP... | Answered on Aug 12, 2009

I've had a similar situation with a Magellan, it would power off despite being plugged in.

Its usually a battery issue, perhaps its not getting enough power? You could try to unplug it and do a "hard battery reset" depending on the type of battery. Keep turning it on and let it run out, until it wont even turn on anymore, after that plug it into a charger while off and allow it to charge completely. Turn it on, see if it still shuts off.

Good luck!

Garmin GPSMAP... | Answered on Jun 17, 2009

Check the pins at the connector on the back of your unit. Make sure one of them is not bent or broken off. One of the pins on mine is missing about 1/16" of the tip. My boat repair shop says it's the power lead, but Garmin wants $200 for a generic repair.

Garmin GPSMAP... | Answered on May 25, 2009

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