How do I activate the 1490T lifetime traffic?

I'll stand corrected if someone says otherwise, but I think the nuvi xxxxT GPS units with ad-based free Traffic are traffic-active right out of the box.

Aha, check page 34 of the Owner's Manual:

http://www8.garmin.com/manuals/3130_OwnersManual.pdf

Just turn the Nuvi while powered by the traffic receiver in your vehicle and your service is activated. You may not see any icons on the map screen indicating traffic reception unless you are in an area covered by the traffic service. Unlike the TomTom traffic receiver which shows on the screen all the time, the Nuvi's only shows once traffic data is actually being received.

When I go to setting/traffic..it not on..and I need to go to garmin.com/fmtraffic to obtain a code ..then it ask me to input the code to activate??? I bought the unit for about a month now, and I've never receive any traffic information. I am in Vancouver,BC. and the lifetime traffic should cover this area.

Make sure you have the latest traffic update from the Garmin website. Use the WebUpdater program to update the unit.
Ignore inputting the traffic code, this step is not needed.
Your receiver has not has not received traffic signals yet.
I have a 1490t and it took me several days to receive traffic info. Be patient.

It sounds like a call to Garmin's tech support is in order. If done, please post your results to help others that may be in your situation.

[Edit] Or, as gadgetman suggests, wait a while longer. As described in the owner's manual, "The susbcription activates automatically after your nuvi acquires satellite signals while receiving traffic signals..." Be sure you're in a strong FM Traffic signal area and leave the nuvi/traffic receiver on for a while. Take note if traffic in your area is available 24/7 or just at certain times of the day. Also, it can only help to loop your power cord over your windshield's rear view mirror rather than have most of the power cord dangling down by the floor of your vehicle, since the cord serves as the traffic antenna.

A few other thoughts: Does your traffic receiver have LED lights indicating when FM traffic is being received? If so, check and see that it is receiving a traffic signal. Does your windshield have any built-in heater or antenna features that may limit the traffic FM signal from reaching the traffic antenna? Note also that the traffic receiver is active only when connected to an external source of power. The nuvi's internal battery will not power the traffic receiver so you will need to have it connected to a live 12V "cigarette lighter" socket in your vehicle.

It appears that Traffic for the Vancouver area is available only 7 AM to 8 PM on weekdays:

http://www.totaltraffic.com/CoverageAreas/CoverageMap.aspx?M...

Seattle, on the other hand, has Traffic available 24/7.

I am also in Vancouver and I have gotten a few (ie, 2) traffic alerts, but they seem very rare (and outdated). Areas of coverage are also minimal. One of the alerts was when I was driving downtown (during the Olympics) and the other one was on the Knight Street bridge.

Not sure how the alerts work with your units. I'm in Burnaby and mine works (i think). Goes off yellow quite a bit. So far the yellow warning never warranted me changing course and i wouldn't say it was moderate to heavy traffic either. WongFeiHung could be right in saying the alerts are out dated. Haven't had a red one yet, not willing to travel the hwy during rush hour to find out. I do notice that my unit takes at least 10-15 minutes when i first turn it on before the traffic icon shows up. Guessing traffic updates are 15-30 minutes apart. I now also only travel in traffic map mode, get caught pushing buttons when driving gets u a fine now. Gotta be all hands free now.

What's yellow and red?..I've never had any of those appear on my unit.The only red is Hwys and yellow for main roads..But I think I do have that traffic icon on the left, near the top..Does that mean that I have traffic alert? I remember one time when I am approaching the US border, American Jill suddenly said.."traffic ahead"..Was that traffic alert is all about?

Best thing to understand the icon's is to look in the manual. In this way it will show you the icon as and where it should appear. If you do not have the manual it can be downloaded from Garmin.

On mine i see two green car icons side by side a about the middle, on the left side of my map. When traffic is a bit heavy it blinks Yellow. You can then click it and you'll get another screen where you can click 3 other icons