2012 Tundra code C1340 and C1311

I was towing a trailer today and noticed that the VSC light was on. I checked codes and found C1340 (Center differential lock circuit) and C1311 (open in main relay 1 circuit). I think this latter is for ABS. The light would usually turn off when the rig was parked for a while and then came on again after some driving, always about the same distance.

My truck is fitted with an aftermarket brake controller, I believe a Tekonsha. It has a number on the screen that indicates braking force applied to the trailer. When braking, this number is usually between 1 and 4, but as soon as the VSC light came on it would sit solidly at 0 unless I used the brake lever on the controller itself. I think trailer brakes worked normally despite this.


Since when does the Tundra have a center differential?
Where is main relay 1?
Could a mismatch between front and rear axle speeds cause this? The rear tires may have squished down a bit under the load.
How on earth does this interact with the brake controller???

 

Bump. Any ideas anyone?

 

Do you have the same symptoms without the trailer?

 

Well, sort of. Before I hooked up the trailer the light would come on at start up and go away after a few feet of driving. With the trailer hooked up, it would come on and stay on for miles at a time. Oddly enough, it seemed to go off if the truck/trailer sat still for long enough but always came back again. I haven't driven the truck since then.