GTM 21 Woes

abalaam · Occasional Visitor Joined: Nov 23, 2007 Posts: 3

With the large amount of posts on this forum (and other places on the web) I should imagine that none of you are surprised by the title of this post...

I have recently got a Nuvi660 with GTM21. The Nuvi arrived with version 3.8 firmware. I don't recall what the firmware version of the GTM21 was. Once I got it all set up in the car, I went out and about. I noticed that all the time I was out, the status LED on the GTM21 was always solid amber and the traffic info diamond on the main menu screen was greyed out.

The next time I went out, a little further afield, the status LED went green, and the info diamond was no longer greyed out, and I could then select the traffic incident screen and see traffic problems (albeit over 100 miles away!)

Subsequent times I went out, most of the time the status LED was amber, and I got no traffic info.

This, I think, is the same behaviour as most people have reported on this forum. My car is a 10 year old Mondy with heated front screen, which probably won't help!

I installed the webupdater and updated the Nuvi to version 4.1 and accepted the GTM firmware upgrade (4.5 I think). Went back to the car, turned it on, and after the unit had upgraded the GTM21 and sorted itself out, saw the status led go green. Wow, good upgrade, I now have traffic info. Wrong! the info diamond on the main menu was greyed out. No traffic info. The unit seems to perform in the same way as before -I get traffic info where I got it before, and don't get it were I didn't get it before. The main difference being that the status LED is now always green, never amber - not even when starting it up.

A few days after installing V4.1, I saw that V4.2 was available, and with it V4.6 of the GTM firmware -'Great' I thought - they must have found a bug with the LED colour setting and have now fixed it. I upgraded. The GTM21 status LED is still always green, and most of the time I do not get any traffic info.

I have noticed that this green status LED flashes occasionally, but not in any regular manner - just seems random.

So, two upgrades have taken me from almost constant amber and no traffic info to constant green and no traffic info! As an experiment, I took the whole setup indoors, folded the antenna up so it could not get a signal, and turned it on. The status LED is still green (but random flashing a little bit more) and there is no traffic data.

I have twice spoken to support people at Garmin, two different people, two different days, two different explanations neither of which was convincing!

Has anyone else seen this behaviour? Is there any way that I can get the Nuvi to tell me the signal strength and station that it thinks it is getting traffic info from? I have seen mention on this forum of two different diagnostic screens, but neither of them seems to have any useful information.

If I turn the unit on whilst holding down the top left of the screen, it will go into maintenance mode. This has two or three screens that seem to have something to do with the traffic info, but don't say anything useful - and when the unit is in this mode, the traffic status LED does not light up at all - so I think the GTM21 is not turned on when in maintenance mode or maybe there is a way of turning it on, but I've not found it.

If I press on the time for 6 seconds, it goes into some sort of test mode (where it forgets the time) but does not give me any useful info on the GTM either - though the GTM remains on (the status LED is green)

trafficinfo · Occasional Visitor Joined: Nov 25, 2007 Posts: 6

hi, go to the odometer screen and press the center of the odometer for 6 to 8 seconds. then press next 6 times aprox and you will see the GTM Status Screen.

Now, if the GTM 21 LED is green then Mode should be only 5 (locked to RDS subcarrier and receiving messages). If Mode is either 3 (scanning frecuencies) 2 (analizing data) and even 6 (IDK) the LED should be AMBER unless Mode was 5 a few seconds ago and the receiver is still in mode 2 or 6 trying to decode messages again then after a certain timeframe the receiver will give up on that frecuency and start scanning the hole spectrum again , Mode 3.

Depending on how many FM stations show on the FM table (not all necessarily belong only to Garmin's traffic provider, here in Toronto Canada it also shows their competitor Navteq RDS frecuency) and how many other frecuencies the receiver thinks it has TMC messages then the receiver will start analizing those few frecuencies only for a few 2 or 3 seconds but spending more time on YOUR VALID LAST RDS-TMC CARRIER until it finally gives up and start the before mentioned scanning of the hole spectrum searching for at least a new frecuency with valid TMC messages.

I have a c550 and just updated my GTM 20 firmware and the unit keeps performing perfectly as indicated above. Too bad here in Canada (only Toronto, Ottawa and Montreal) we only get updates (including Slow Traffic events) from Mon-FRi 5 am to 8 pm but in the weekends it still show the old construction events.

In regards of the Flow Info we (c550) get (Slow Traffic events) most of them are only a 1 minute Delay. With last Nuvi 6xx firmware it seems that now those unit show Delay Times higher than 1 minute. The same happens with the TomTom units here in Toronto , only 1 munite delays. On my unit a have seen a few 4 or 5 minute and just a few more but iot is always a combination of 2 or more events. Here, Tomtom uses the same TTN from Clear Channel provider as Garmin.

My question for you UK users is Are you getting ONLY 1 MINUTE DELAYS when using RDS-TMC either Trafficmaster or ITIS? and also How about the Tomtom Plus Traffic via GPRS , Does it show only 1 minute delays as well. We do not get Tomtom Plus Traffic service here in Canada (only road conditions but no traffic events) yet but in US it seems to show the actual delay times accurately.

Thanks

mwfox · Posted: Sun Nov 25, 2007 8:05 pm Post subject: Traffic delay times

I am using a Nuvi 660 with Trafficmaster data - and get relevant traffic delays of any time (not just 1 minute).

How is the signal strength in Canada - do you get good reception with just the aerial provided with the unit? I have had to connect mine to the car aerial to get reasonable reception in the UK.

abalaam · Occasional Visitor Joined: Nov 23, 2007 Posts: 3

trafficinfo · Occasional Visitor Joined: Nov 25, 2007 Posts: 6

then definetely there is something wrong. do a back up first then try a master reset just in case. if it does not help roll back the firmware (I always keep a copy of every firmware for my c550 just in case) . there is a website that has them. see what happens and then reinstall the latest firmware again (it fixes the delay times for nuvi 6xx). there is nothing else I can think of.

Here in Canada and I could say also US (tested Detroit, MI traffic service from 30 km of US border) with the only exception NJ/NY and maybe Chicago, IL , ERP power levels from FM stations are quite high , usually around 40 kW and even more , therefore reception is very good everywhere within the coverage area. I have never seen mi GTM going amber within the coverage area which covers a circle of 60 km radius from the CN Tower where the transmiter are. Montreal, PQ is an exception so far because they are still broadcasting far away from one of their Clear Channel FM stations in Vermont, US. The rest of us are quite happy. my GTM 20 is just laying on top of the dash and goes down to where the cig lighter is. That is more than enough around here.

Our only complain so far is that it only works in Canada from 5 am to 8 pm Mon - Fri and of course the usual innacuracies of the reports.

abalaam · Occasional Visitor Joined: Nov 23, 2007 Posts: 3

swing · Posted: Tue Nov 27, 2007 8:20 am Post subject:

	PocketGPS
	Web