GTM21 traffic issues

[emmanueld]

Swing, if the traffic does not work EVERYWHERE, what is the point? It is a bit like if the SatNav itself wasn't working everywhere.
At least, you would expect it to work wherever Garmin / 'everyone selling it' says that it should work, i.e London, some main cities and all main motorways. Basically, you would hope that it will work where you need it to work.
From my short experience, and what I have read here or there, it works from time to time. There are certain places where it NEVER works (M25, most of the M4). The rest of the time, it is very unpredictable. In any case, way below my expectations, expectations that were given to me by Garmin.

This being said, the communities of users like PGPSW are very useful, because altogether, we maybe able to find solutions to our problems. I really would like Garmin to participate to these types of forum, as it would probably speed up a fix.

[peaton]

I am prepared to accept that the traffic information may not work everywhere, that is to be expected. I would like it to work somewhere though. So far my GTM 21 has been of no use at all. It has been little more than a distraction as I peer down to see it it has the LED turned green and then on the odd occasion it does receive a signal looking at the still greyed out traffic icon on my C510. I don't want to bring it back again. I want it to tell me about traffic at least some of the time, that is what I was sold and that is after all what the GTM 21 is designed to do.

[paul3]

Hello everybody!

I have finally bitten the bullet and connected the aerial lead to an externally fitted mobile phone aerial that had been (fortunately) installed by the previous owner of my vehicle. While sat in the car-port with the vehicle, I've finally received a traffic warning. But as others have found, the two cars on the bottom taskbar were greyed-out and the amber light was also on. (Previously, I could not get a signal in the car-port).

So, obviously there is an improvement with reception by having an external aerial of some sort. (At this point I have not been out on the road).

I understand that a lot of people will not have such a facility, but I'm only trying to help people in a similar situation. Because as I understand it, phone and radio aerials are normally a certain length to receive corresponding transmission frequencies.

Please feel free to correct me if I'm wrong!

Paul

[JoshT]

I have to agree with others the GTM21 is not fit for purpose.
Garmin have stated to me that GTM12 (latest) & 21 are no different in their receiving capability. I disagree Its been proved on this forum that the GTM21 receives 3 or 4 levels below that of the GTM12 meaning the difference in picking up or not picking up traffic information.

I understand that RAC live is a subscription services - Albeit that Garmin include life time subscription in the cost of the product. I'm guessing Garmin pay some kind of royalty fee for this service (I may be wrong) - so surely Garmin can put some pressure on RAC live to crank up the volume/ install additional transmitters etc.

Alternatively, replace the GTM21 with a receiver that has the ability to connect to an external car aerial

[portman]

Yesterday we drove from Portsmouth to stansted airport via north london and then back, a total of about 8 hours driving. The only time i got traffic was between chichester and home for about 2 minutes on the way back. I tried several things to make it work but nothing seemed to work.
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[Harveyc]

My daily commute is from just outside Portsmouth to the Heathrow area, up either the A3 or M3 and round the M25.and the only place where I've noticed the 660 not receiving traffic info is just north of Hindhead on the Thursley bypass. As I've posted here before I've been well impressed with the traffic performance of this unit, especially throughout the south east. Two colleagues have bought Nuvis after trying mine and neither has any complaints with the TMC, one commuting from Lewes, the other from Salisbury.

Clearly the hardware works, so it must be the antenna placement and/or weak signal depending on your location. As a parallel, my friend's struggle to get reception on their telly isn't Panasonics's fault but is due to their geographical location in Cumbria and being poorly served by the transmitter infrastructure.

I've just come back from southern France where the 660 was a lifesaver routing around some very nasty accidents. I don't understand it, the TMC thingy can't just be working for me and my workmates.

[leehenty]

I have been doing some comparisions between the Nuvi 310d with GTM12 and the Nuvi 660 with GTM21 and the results are as follows:-

Nuvi 660
Software Version 2.70
Audio Version 1.40
GTM SW Version 3.70
GPS SW Version 2.90
Bluetooth SW Version 2.40
GTM 21 (Part No 10R-023487)

The Nuvi 660 hardly ever picks up the TMC Live traffic reports (in a 4 hours journey I had traffic for all of a few minutes between Reading and London). When I had a Nuvi 310D with GTM 12 traffic receiver I never had any problems with picking up a traffic signal or keeping the signal. The Nuvi 660 with GTM21 hardly ever picks up a signal and if it does then it loses it if you start driving.

I have performed some tests with both a Nuvi 310D with GTM12 and a Nuvi 660 with GTM21 in the same car at the same time and the results are as follows:-

Locate car in East Reading (ie between J10 & J11 M4)

Clear the FM table entries on both the Nuvi 310D and 660.

On doing a search the Nuvi 660 picked up 1 TMC Live entry with details as follows:-

GTM Status

Tuned Channel 95
CC 12
SID 7
LTN 7
Level 8
Error 0 (but also showed errors of 9,30,31,56,66,14,7)
Mode 5
N Sync 0

GTM21 was horizontal on the windscreen and the windscreen is a standard windscreen (well actually it doesn't make any difference as you can hold the unit outside of the car and it will only pick up 1 signal in this location).

Nuvi 310D with GTM12

GTM Status

Tuned Channel 95
CC 12
SID 7
LTN 7
Level 5 (arial was not on screen at all but in centre of car and always picked up a signal - if put on the windscreen then signal increased)
Error 0
Mode 5
N Sync 0

In the FM Table Entries the entries were as follows:-

Nuvi 660 with GTM 12 (1 entry only)

Frequency 970
Validation Code 4
CC 12
LTN 7
SID 7

Nuvi 310D with GTM 12 (7 entries)

Entry 1
Frequency 975
Validation Code 4
CC 12
LTN 7
SID 7

Entry 2
Frequency 970 (ie 2 Ten FM - Reading transmitter)
Validation Code 4
CC 12
LTN 7
SID 7

Entry 3
Frequency 1029 (ie 2 Ten FM - Andover Transmitter)
Validation Code 4
CC 12
LTN 7
SID 7


Entry 4
Frequency 970 (ie 2 Ten FM - Reading transmitter)
Validation Code 4
CC 12
LTN 7
SID 7

Entry 5
Frequency 1013 (ie Classic FM)
Validation Code 11
CC 12
LTN 0
SID 10

Entry 6
Frequency 1029 (ie 2 Ten FM - Andover transmitter)
Validation Code 4
CC 12
LTN 7
SID 7

Entry 7
Frequency 1026 (ie Fox FM)
Validation Code 4
CC 12
LTN 7
SID 7

If you drive around then the Nuvi 310D with GTM12 always keeps a traffic signal but the Nuvi 660 with GTM21 does not.

2nd test

Go to West Reading (Near J12 M4)

Nuvi 310D with GTM12 always picks up traffic data

Nuvi 660 with GTM21 does not at ground level

However, if you then go into my house and go upstairs to one of the bedrooms you can then get a traffic signal at last because the unit is a lot higher up.

If you do a FM Spectral Scan then the results from the bedroom show:-

97.0 FM 5 TMC (ie 2 Ten fm)
101.8 FM 5 TMC (ie Classic FM)
102.6 FM 5 TMC (ie Fox FM)
102.9 FM 5 TMC (ie 2 Ten FM)

If you go to the FM Table then you get 4 results (however at time the 4 entries cannot be seen but if you press on lines 1 - 4 on the screen then the items appear. Eventually the results get to appear correctly). The FM Table for the Nuvi 660 with GTM 21 then shows:-


Entry 1
Frequency 1026 (ie Fox FM)
Validation Code 4
CC 12
LTN 7
SID 7

Entry 2
Frequency 1013 (ie Classic FM)
Validation Code 3
CC 12
LTN 10
SID 10

Entry 3
Frequency 970 (ie 2 Ten FM)
Validation Code 4
CC 12
LTN 7
SID 7

Entry 4
Frequency 1029 (ie 2 Ten FM)
Validation Code 3
CC 12
LTN 7
SID 7

The GTM Status on the Nuvi 660 with GTM21 shows:-

Tuned Channel 151
CC 12
SID 7
LTN 7
Level 10
Error 70 (with other errors being shown as - 77, 78, 75, 64, 44, 27, 29, 33, 36, 31
Mode 5
N Sync 0

Another thing to note with the Nuvi 660 with GTM12 is that if you get a Traffic signal as you turn on then it will stay for a while. If you then remove the Nuvi 660 from the cradle and then re-connect (ie to stop the traffic signal and then to start it again) then the unit will never find a traffic channel again (even though you have not cleared the FM table and you either leave it in Automatic or perform a manual search which takes about 5 minutes).

The Nuvi 310D with GTM12 re-finds the signal almost instantly.

The results have been passed to Garmin and I am awaiting their reply.

[cjthebrave]

Hi people.
Just to add to the debate, I live in Stafford and travel in the M6 corridor a great deal. Had C510D at Christmas and so far it has failed to activate the Traffic Master subscription - allegedly since it has never had both TMC and GPS signals at the same time.
Have tried aerial in different orientations, and used it for several days in my area, plus 2 days travelling E-W to Lincoln via Derby - still nothing.
Someone mentioned "the information included with the product" - well I had none specific to the GTM21 in my product - I downloaded the GTM21 owners manual from Garmins website. . . . . for what it was worth
So far - very happy with C510 - 'does what it says on the tin' - as for the GTM21 - 'does nothing'.
I have reported this to Garmin, but no response yet. Seems to me to be a bit of a con selling this as a working product when from reading above and my own experience, it clearly doesn't. Should have bought the cheaper product without the GTM21 and still sat in the same traffic queues, could have bought a few CD's to listen to instead whilst stranded. I will be taking this up with Garmin, but meanwhile will stay 'tuned' to this channel to see what others discover or suggest.

[swing]

[portman]

There is a difference in signal strength between my car which has a normal windscreen and a citroen picasso with an athermic screen. On the same journey i was getting a signal of between 7-11 compared with 4-7(on dash and side windows, not on windscreen) in the picasso, the difference between getting traffic or not.
I also wonder if certain cars act as a better 'Faraday cage' than others causing them to get bad signals.
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Tomtom 500

[JoshT]

Leehenty - I hope you have more success with Garmin than I did

I used to have a 310D and could pick up TMC in the Reading area on the M4. With my newish 660 I can't. I rang Garmin and explained that people in this forum had actually tested the 310D and 660 side by side (I'd emailed somebody in support with the URL).

Garmin informed me there was nothing they could do - GTM21 and GTM12 have the same level of receptivity.

With your results I hope Garmin can come up with some software tweats for the GTM21.

Thanks

Josh

[emmanueld]

Almost a month after writing to Garmin to let them know that my brand new 660 was not giving me satisfaction because of the TMC, they replied this morning to advise me to buy a GTM10. I have know idea what this is, whether it will help my 660 to work, and I would have to buy an additional accessory to get the features that I should have got when I bought he 660. Anyone can advise?
Anyway, I am amaized by the poor quality of the service in this instance. Obviously, in their email, they do not aknowledge that they might be a problem.

[MarkieT]

Hi all,

I purchased a Nuvi 660 on th 31st December and have to say that I'm glad to report that TMC pretty much works every day, I live just outside Dudley (West Midlands ) and travel around the Midlands area quite a bit.

The way I've got my GTM21 setup (if anyone's interested) is the Nuvi is fixed to the Windscreen at the Lower Right had side and I then have the aerial Lead going up the right hand side of the Windscreen, hooked over the Sun Visor and then stuck onto the Windscreen again. I always have the 2 lights on on the Power Cable, iit ( has only happened once) had 1 light on, so I reseated the Nuvi back into it Cradle and the 2 lights came on!!!

The only thing I have noticed which I think can be quite funny is that the Traffic Info it supplies can be for an area around 200 miles away!!


Thought I'd share my setup and experience!!


Cheers


MarkieT.
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Garmin 660FM
Nuvi 3598 LMT D - Firmware 4.40
iPhone 5S CoPilot Live

[JoshT]

[swing]

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