A couple of questions to get started. We really need the answers before we can give you more help.
First, does the Suburban have the factory trailer package with the trailer brake connector already installed in the vehicle? Check the truck's documentation. If there is one, it'll be tucked up under the dashboard near the steering wheel somewhere. Should be a fairly large 4 conductor connector of some kind.
Second, do you already have a trailer brake controller that you want to install? If not, the Prodigy or P3 are the best choices. Prodigy is going to be a little less expensive as the P3 is the latest and greatest version, but still very good.
If you determine that the truck has the connector for trailer brakes under the dash, buy your brake controller with the GM adapter. Makes installation a LOT easier.
Third, does the Suburban have the factory trailer wiring? If so, it'll have a 7 pin connector on the rear of the truck near the hitch. If not, you are going to have to install all the wiring to connect the trailer to the truck.
Speaking of hitches, what kind of hitch is on the Suburban?
It would also be very helpful to know what size trailer you have. Most of us edit our profile to include a signature that includes your trailer model or size so that we don't have to keep asking.
When you say you got the lights working, do you mean plugged into the truck?
The more baseline info you can give us up front, the more help we can give you.
'12 F250 4x4 Super Duty PowerStroke 6.7 diesel
2011 to present: '11 Cougar 326MKS
1999 to 2011: '99 Sunline T-2453
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