Troubleshooting No Or Low Audio from Microphone on a 2006 2013 Using a Garmin/Road Tech

Troubleshooting No or Low Audio from Microphone on a 2006 – 2013 using a Garmin/Road Tech 660 or 665 GPS.

Problem: The person I am talking to does not hear anything or my voice is low.

Make sure you are using a Harley Headset or J&M headset made for the Harley. To test the headset talk to the passenger on intercom or make a CB call. You can also use the intercom push to talk switch and blow into the helmet microphone, you should be able to hear yourself in the helmet speakers. If you do not hear yourself then see your maintenance manual and look under “Low or No Microphone Volume” Make sure your intercom in on and the volume is adjusted.

Substitute the helmet headset by using another headset.

Testing the Input & Output resistance of the H-D Bomm. To perform this test you will need a quality digital volt/ohm meter.

Output: With an Ohm Meter set on the ohms function place one of the meter probes on the tip of the 2.5mm jack and the other meter probe on the shaft of the plug. You should read about 74 ohms give or take a few ohms.

Input: You will need to remove the Bomm for this test. With an Ohm Meter set on the ohms function place one of the meter probes on one of the wires from the Bomm and the other meter probe on the other wire from the Bomm. The wires may be Black, Orange or Green in color. It does not matter what the colors of the two wires are. You should read about 44 ohms give or take a few ohms

Testing the Output Signal of the Bomm. To perform this test you will need a quality digital volt/ohm meter with a Milli-Volt scale (thousands of a volt).

Connect your meter to the 2.5mm jack of the H-D Bomm using alligator clips, see picture below. Touching the meter leads with your fingers will result is a bad reading. Set your volt meter to test AC volts and place the scale of the meter to Milli-Volts. Be sure the meter leads or alligator clips are not touching one another.

You should read between 0.10 to 0.70+ milli-volts AC when talking into the helmet microphone. The louder you talk the higher the voltage will go. It is not uncommon to see a reading over 0.100mv. This voltage will vary according to the lever of your voice If you do not see the voltages above then test the input of the H-D Bomm by checking the voltages described below.

If you have connected to pin 33:

Test the DC voltage at pin 33 & ground of connector 28A. Set your meter to DC volts and place it on the 00.0 scale.

You should read 3.5 to 3.7 Volts DC.

If you do not have this voltage then troubleshoot the radio using your maintenance manual. Look under Low or No Microphone Volume.

If you have connected to pin 9:

Test the DC voltage at pin 9 & ground of connector 28A. Set your meter to DC volts and place it on the 00.0 scale.

You should read 7.5 to 8.5 Volts DC.

If you do not have this voltage then troubleshoot the radio using your maintenance manual. Look under Low or No Microphone Volume

Testing the 660/665 GPS mount/wiring harness.

This testing procedure requires that you have the Car mount that comes with the Garmin Zumo.

Connect the 2.5 mm microphone jack from the HD-Bomm into the side of the car mount cradle Connect the power output between the cradle and the cigarette lighter on the inner fairing Connect the 3.5 mm audio cable between the side of the Garmin unit and the aux input on bike’s radio Once connected:

 Link up the phone  Connect the helmet  Turn on the ignition switch  Make a call

If you can make a call and the person can hear you then you have a BAD bike mount/wiring harness. Call Garmin for a free replacement.