Speed sensor?

[Suburban_Tyler]

I noticed a couple days ago on my 90 R1500 that when I came to a stop that my brake pedal would pulse something like once a second like the abs was kicking in but being really slow or a caliper was sticking on the slides or a piston was bound up. Pedal doesn't seem to go down further with the pulsing settling, feeling. It didn't do it every time I stopped. Just sometimes. The suburban didn't really pull one direction or the other when i applied the brakes. It did seem to take slightly more pressure to stop. I'm a very casual driver. I jumped in the suburban last night and noticed the brake light on the dash being on. I set the parking brake and it lit up a little brighter so I know it wasn't that. I unplugged one of the plugs on the abs controller and plugged it back in. It sounded like something rest inside of it. The brake light also went off. I drove around town a little while (30-35mph) and noticed the converter locking up for a second and then unlocking again. It did this a few times before I hit a hill and it stayed unlocked. That's when I noticed the speedometer going up and down 3 to 5 mph. I got up on the highway, the converter locked as it should have. The speedometer started going up and down 20mph. The brake light came back on. I unplugged it and replugged it again and the light went off. I drove it again and recorded an almost 9 minute video I will hopefully share on here. The bouncing of the needle came and went but right at the end is when it started going crazy and the brake light came back on again. I unplugged the abs controller and left it unplugged. The light went off and stayed off. Speedometer still bounced. I don't know if I have multiple issues or if they're related. I do have the electronic sensor in the transmission for the speedometer. I know or at least i think I know that the abs probably reads off the same sensor. What I am unsure of when the pedal feels like its pulsing. Is it the abs actually activating or is something not moving smoothly all the time and I am feeling it moving in a motion that makes it feel like its settling in a jerking bound up motion. Hard to explain that one.

Here's the video. Don't pay attention to the squeak of the center console lid or the toolbox in the back with the rattling tools. I've got a tire that nobody can seem to balance.

Speed sensor - YouTube