LMT or LM.

Garmin shows the traffic receivers for the 2557LMT are built into the cord.

https://buy.garmin.com/en-US/US/on-the-road/automotive/2013-...

GTM™ 60 HD Digital Traffic Receiver
010-01031-00
$69.99 USD

GTM™ 36, North America
010-01009-02
$69.99 USD

Which cable came with your 2557?

The Garmin site for the nuvi 2557 states "Lifetime traffic antenna/vehicle power cable" and not a "traffic receiver/power cable" so I expect that the traffic receiver is built into the GPS itself and the power cord is used only to supply power to the nuvi and to serve as the antenna for the traffic receiver. Knowing the cord's Garmin model number should help clear this up—or further muddle things for us

If you live in or frequent an area covered by traffic coverage, you could also see if traffic is active on the device. Here's the coverage list:

http://www.navteq.com/rdstraffic/

Here's a bit of a discussion:

http://www.gpscity.com/questions?qid=33831

some have them in the cord and some not?

It could be since there have been earlier nuvi models that had a mid-series hardware change. If so, you'll need your nuvi's serial number, then either get lucky with a Google Search or contact Garmin.

But first, tell us what model power cord you received—and if you have traffic available where you live, the results of a search for traffic using your nuvi in your vehicle with the cord attached. Remember that the nuvi itself, unattached to the Garmin power cord, will not provide traffic results.

Charger cord.
Garmin TA20 Charger P/N 320-00239-70

The TA20 is a traffic antenna so I expect your receiver is built into the 2557 itself. Here's a faq and a bit of a discussion:

https://support.garmin.com/support/searchSupport/case.faces?...

http://www.poi-factory.com/node/41397

So it looks like I have an internal traffic chip. It's too cold now but tomorrow I will take it for a drive on a major Hwy where I used to get traffic with my older unit that I gave to my daughter.

Thanks for all your replies.

If you had a older unit with traffic you may find the newer models display different.Prior to my 2597 I had the 265 and was use to seeing the traffic icon with color coding all the time.Not so now. I took this from the Garmin FAQ.

How do I view traffic information on my nuvi series device that uses map tools?

This article only applies to automotive devices that use the map tools menu, which include the nuvi 55, 56, 65, 66, 2407, 2408, 2507, 2508, 2509, 2609, 2707, 2708, 2709, 3507, and 3508 series devices.

If you have a nuvi connected to a traffic receiver or antenna cable, and you are in a traffic coverage area, in order to view the traffic information on your device, you will need to use the map tools menu. Even when you are not using the traffic map tool, if there is traffic along your route, the device will verbally notify you of any upcoming traffic.

Please view the following FAQ about how to use the map tools on your device: https://support.garmin.com/support/searchSupport/case.faces?caseId={f7dc4bc0-6715-11e2-f3fb-000000000000}

You can also browse the map to view the traffic in your area:

Touch View Map
Touch the screen on the map
Touch and drag you finger on the screen in any direction to move the map to view other locations

The traffic can be viewed on the device using either method.

The following FAQ provides the information about the traffic icons: https://support.garmin.com/support/searchSupport/case.faces?caseId={ce5da670-0fc9-11dd-dc9c-000000000000}

Info on Traffic trends.

Do I need an FM traffic service to use trafficTrends on my device?

You do not need an active FM traffic service in order to use trafficTrends on a device. Rather than live traffic alerts, trafficTrends uses collected historical traffic information. As such, it can be used with or without an active traffic subscription or receiver. Using a trafficTrends-enabled device with an FM traffic service will provide you live traffic alerts, if available, but will not enhance the trafficTrends feature since the information used does not come from live traffic services.

You can learn more about trafficTrends by reviewing the following article: https://support.garmin.com/support/searchSupport/case.faces?caseId={9b48d480-abc6-11df-6dba-000000000000}

Please note: The zumo 590 can only connect to traffic information with a subscription in the Smartphone Link app (User's data plan charges, if any, will apply.)

I have been using my Nuvi 2797 since Christmas and found it a little disconcerting the first couple of times I used it not to see any indication that the traffic feature was indeed working. My older units had a traffic icon on the map screen and this changed color depending on the state of the traffic and you had to go to a different screen to actually see the traffic information.
The first time I knew that the traffic feature was working on my 2797 was a verbal traffic alert stating that there was an accident a few kilometers ahead on my route and then a traffic summary appeared on the screen where the junction view normally is and the section of highway that was affected was shown in red hatch marks on the map itself. I have grown used to this now and find it a lot easier to use compared to the old system. The traffic updates in my area are quite accurate and have been very helpful during the recent bad weather.