Missing Radar Option on a Garmin® Chartplotter

Checking Power

The radar has a LED light near the power and network cable check for what color displays.

With the radar turned off, check the fuse in the power cable. If the fuse has blown, replace it with a properly rated fuse (check the radar’s installation instructions for proper fuse ratings).

Check the cable for any loose connections. Repair or replace the cable as needed.

Some open array radars have a voltage converter box installed. Two readings are necessary, one before the converter box and the other at the end of the power cable. The two measurements need to be nearly identical.

NOTE: The converter must be connected to the boat battery through an appropriately sized fuse. All GMR™ xHD2 radars that utilize the voltage converter will include a 30A slow blow fuse. GMR™ xHD radars that use voltage converters require a 15A slow blow fuse (not included). For more information, consult the radar’s installation manual.

Power Cable and Power supply

• Fuse - Check the inline fuse on the power cable. The fuse holder installs on the red wire of the power cable. Check the fuse and replace if blown. Sometimes broken wire in the fuse is difficult to see— connect a multimeter to both ends of the fuse and measure for resistance or continuity setting. If the fuse is good, it should be close to 0 ohms shown on the multimeter

• Power Supply - If the power cable is going to a panel or switch, connect the power cable temporarily to a fully charged 12volt battery and check to see if the unit powers on. If the circuit panel or the switch has other devices connected, move the Garmin device to a different switch or circuit panel

• Wiring - There are three primary areas to check

  • Wire size: Are there extensions on the power cable or from the panel to the battery? What gauge of wire is on the power cable? It may not be a low enough gauge wire for the distance or load

  • Installation: Look for loose wire, low-quality wire , faulty termination points, or incorrect terminals. If corrosion is present on the wire at the electrical termination points, cut the old ends of the wire off (power and ground), strip back sheathing, and make a brand-new connection or replace the power cable

  • Check for fuse panel or wire block used. Temporarily bypass any fuse panel or wire block and wire directly to the battery. Ensure good connection points

• Power Cable Connector Head - Check the brass contacts on the power cable connector head. These should be tight, not loose, and should show no signs of corrosion. Clean light corrosion with a brush and some dielectric grease to clean the brass contacts, also clean the port power side. If corrosion is extensive on the port side, it’s likely that this has seeped inside and damaged the unit. If corrosion is extensive on the power cable, replace it as it could have spread into the cable

• Voltage - Use a voltmeter to check the power cable connector. Testing the connector head verifies whether more than 12 volts are coming through the unit’s power cable. Garmin chartplotters and fish finders are consumers of power, and the voltage needs to be more than 12 volts. If it’s under 12 volts, the unit may not successfully power up

  • Power Converter - The power through the converter, when the converter is not under load, should match the power as it goes into the converter on the other side.

  • Set the multimeter to DC. Some multimeters have symbols representing AC, DC, and other test modes. Check the owner’s manual that came with the unit, but the character is typically represented by a V, mV, or A with a line and a dashed line if that’s not available. Some meters will have a letter combination that usually makes it straightforward for DC and AC

Test the Battery – Charge the battery fully, remove from the charger, and allow the battery to sit for 12 hours before trying with a voltmeter. When testing the battery for voltage, the engine should not be running.

Check for Voltage Drop - What’s an excessive voltage drop? On boats, the ABYC (American Boat Yacht Council) dictates a maximum voltage drop is 3% for critical circuits. What is considered critical? Circuits used for navigation lights, bilge pumps, VHF radios, GPS, radar (devices and systems which bring the boat safely back to port). 

Advanced Voltage Test

1. Verify that the device is connected correctly. Verify ground wire is not loose or has corrosion build up

2. Use a voltmeter on the bare wire end of the power cable

3. Watch the voltage readings on the meter. At the same time, try to power on the device. You will either see a steady reading or a drop-in voltage

   • Voltage Drop: - If the voltage drops when the device tries to power on, there is not enough power getting to the device. For example, when powering on the engines or increasing speed, the device powers off. Try wiring the device directly to a new power source

   • Steady Voltage: If the voltage readings are constant, contact Product Support

Other Causes of Voltage Drop

1. Follow the steps above for Testing the Battery – note volts

2. Switch on the circuit to be tested. Connect your voltmeter to the power cable connector head (8-pin, 4-pin, and 2-pins power cable)

3. Deduct the power cable volts from the battery voltage. Divide the sum by the battery voltage (move the decimal point move to show the percentage)

Example: Battery Volts 13.3

Power Cable Volts 11.9

Balance 1.4 / 13.3 = 0.1052631579 Move the decimal point over two, and the drop is more than 10%

Check Marine Device List:

• On current GPSMAP® chartplotters¹, select Options >  Settings > Communications > Marine Network > Device List to view the devices connected to the Garmin Marine Network. 

 To quickly troubleshoot the Garmin Marine Network, take a new Marine Ethernet cable and plug it into the radar and directly to the chartplotter. If the radar displays with the test cable, follow the instructions below.

1. Inspect the network cable running from the chartplotter to the radar for damage at both ends. If possible, check the cable for continuity with a network cable tester. Recently replaced Ethernet ends verify installation use the Marine Ethernet Installation Instructions to ensure proper installation. Replace the Garmin Marine Ethernet cable if needed. If there are multiple Garmin Marine Ethernet ports on the chartplotter, try another port

2. Does the system utilize a GMS™ 10 network port expander? Check the LEDs above the ports on the GMS 10, are those for the radar and chartplotter lit? If the LEDs are not lit and flashing, check the network cable running from the chartplotter and radar to the GMS 10. Try connecting the radar / chartplotter network cable to a different port on the GMS 10. Repair or replace the network cable as needed. If the GMS 10 has a broken port, contact Marine Product Support to set up a repair

3. Finally, connect the radar to a compatible, working chartplotter and turn on the device. If the radar does not appear on this device’s network list, contact Marine Product Support as a repair is needed.