I installed one of those LED 3rd brakelights on ebay into my 94 Z28 in the process of restoring the engine and stuff. I start the car back up and the ABS inop light keeps coming on. I keep wondering what I might have not reconnected up front by the ABS module, but everything is plugged in. Then I read on here that the 3rd brakelight not working could cause the light to come on. I start thinking that the LED brakelight I installed probably doesn't draw the same current as 2 conventional bulbs, I take the light out of the spoiler and put back the bulbs in their sockets behind the new LED 3rd brakelight and now the ABS inop light doesn't come on. Thanks everyone for the info on here.

 

There's a way to use the LED CHMSL in the SS spoiler.... maybe that would work with your LED's:

http://shbox.com/1/relay_for_ss_spoiler.jpg