2002 2500hd
Its been a problem for awhile now. It started ABS and parking light would come on with moderate acceleration or hard braking and would make hazards on dash flicker on and off dimly, lights would disapear in a couple seconds then return with hard accel/braking. I plugged it in, got A. Missing/bad left front speed sensor. B. Rear speed sensor C. Loss communication with EBCM. So I replaced from speed sensor, cleaned up ground below drivers door. Now ABS light is always on and hazards don't flicker on as often but still do. Problem is when this happens when braking, people behind me can't see brake lights or turn signals. Don't know what to try next. Thanks, Colton

Edit: Also cause hard shift and if hazards illuminate to regular glow (like when u actually turn them on) the truck will "bog" or not want to go, so I let off gas and let it return to "normal state"

Edit #2 Sitting thinking about it, I looked at all the codes sitting at work right now and I decided to clear them, took the truck around the block and plugged it in again. Nothing showing up in powertrain, antilock... ect. ect. kinda baffled by it, will let it run for a day and check it again tomorrow when I get back into work. Still utterly baffled that the ABS, Brake and Hazards are still flickering on dash. hopefully just a ground rather than a new EBCM