Why are these lights on?

I was driving my truck the other day and the rr diff lock light and the abs light both flickered and then came on and have been on since. Pretty sure the locker isnt on cause its seized and hasnt worked in years but the light is on. I had previously done the grey wire mod and i put everything back the way it was but the lights are still on. The truck runs fine but those lights are getting annoying so if you have any ideas i would love to hear them. Thanks!

 

You can pull the ABS codes by connecting pins 4 and 13 on the OBD2 connector with a test wire. The ABS light will flash like blink-blink-pause-blink-blink-blink (this would be code 23).

But, if I had to guess, the wiring harness which connects to the rear axle is loose or broken. That's the only common failure point between the diff lock and the ABS. I bet your ABS codes will be 33 and 34 for the rear sensors. The connector is up by the gas tank above the rear axle.