I got the dud! Problem Forum for the Nuvi 7xx series


Received my Nuvi 750 with the objective of using my existing GTM20 FM traffic and MSN direct receivers with it.

BUT the unit locks up when either the MSN Direct receiver or the FM traffic receiver is powered on.
Both receivers work on the respective Nuvi 6xx series. Unit (V2.2) and traffic receiver(s) microcode are current.

Rounds 1 & 2 with Garmin - they were way off in their diagnosis, but I had a good laugh at their ineptness. I vowed to keep trying until I received a better (more logical) answer.

Round 3 with Garmin - sending a new 7xx series mount to try. I am skeptical, but I can see the connector to the unit may be a weak link. ...and I can always use another mount.

...more later.


It sounds like you may have a short in the cable of the traffic/charger. See if you can return it for a new one. Or a short on the unit where it connects to. Shorted cables can work fine on one unit and cause havoc on another...depending on how the cable is laying at the time.

which antenna ?

which antenna charger cable do you have?

etrex vista, Nuvi 350, Nuvi 650, Nuvi 750(3)

Traffic receivers

I have both the MSN Direct and 2 FM traffic receivers. Also tried a friend's MSN Direct - same problem.

The unit locks up whichever is used.
Works ok with just a dc power cord (supplied with the unit)

Linked to Specifc GPS

Aren't the traffic receivers linked to a specific unit? In other words, my GTM 20 is coded to my c550 so it shouldn't be able to work with anyone else's unit.

I'm not sure, just posing a guess.

Gordon - Jacksonville, FL - Garmin Steetmap C550


Reveivers are linked to the power/receiver ID numbers, not the unit


nüvi 880 - nüvi 760 - nüvi 660 - StreetPilot 2620 - Portland, Oregon


To have a baseline, the GTM 20 FM receivers were tested with my 2 Nuvi 660's, and the MSN direct and FM receivers were tested with a friend's Nuvi 680. Receivers worked with these units. Receiver microcode is current. These receivers plug into the mount.


Maybe you could use the GTM-20 but would have to go through the "Add" a subscription portion, since the GTM-20 is currently ID'd to another unit. May be the same with the MSN.

Tools > Settings > Traffic

........Garmin StreetPilot c550 / Nüvi 765...........

A Garmin question & answer

When I asked Garmin tech support...
"Is it safe to assume that if I buy a 750 that I'll be able to swap the GTM-20 from my 660 to the 750 and the vehicle power cable from the 750 to my 660? If so, is the traffic subscription tied to the GTM-20 so if I have 6 months of subscription time remaining at the time I buy a 750, I can just transfer that 6 months to the 750?"
Their answer was...
"Yes, you will be able to use the GTM 20 with the Nuvi 750 as well as the Nuvi 660. The traffic subscription actually lies within the traffic receiver and will work on any GPS unit that is compatible. I use my GTM 20 with a number of compatible Garmin GPS units and you will not have to transfer the subscription, as the subscription sticks with the traffic receiver instead of the unit."

And that makes perfect sense

And logically, that's how it should work.

........Garmin StreetPilot c550 / Nüvi 765...........

Defective Mount - Nuvi 750

The replacement mount resolved the problem and the MSN and FM traffic receivers work with the Nuvi 750.

What is STRANGE is that I tried my defective mount on a Nuvi 750 at the store and it failed as expected. I tried the defective mount on a Nuvi 760 demo model with FM receiver at the store, and the defective mount worked. I can only think that the gps nav unit may have been turned off (put in simulation mode) but did not have time to play with the unit in the store.