Speedometer and dash lights not working properly and Code PO500

Well, my friend finally caved and had me bring it to the Toyota garage he works at. Found no problems with cluster or electrical. Did find if you removed one ABS sensor from the rear the speedometer works. If two removed it will not. He then found the right rear wheel seal has failed and allowed moisture to get in and screwed with the abs tone ring and whatever else is in that area. He was able to clean it all out and got speedometer working again but recommends I replace both wheel bearings and seals. He has had it for 5 days and is still playing with it to figure it all out. Said all those lights on dash wont go away until the ABS sensor issue is resolved. Most likely after the new components in the rear end. The PO500 code is gone with speedometer working. Will update some more as we figure it out. On another note truck wont last too much longer as it has the dreaded Toyota rust. Truck looks like new but frame is almost toast. Can make an engine that can last 500,000 miles but cant figure out rust. What a shame.

Code C1238, foreign object is attached on tip of rear speed sensor. Never quite figured it out what the substance was. Looked like rubber pigeon crap. Cleaned it all up no dash lights or codes. Test drove 60 miles. All is good. Told to keep an eye and ear and if needed will replace bearings and seals. All is good now. Did find the gas tank is sitting on top of the cradle as the straps have failed from rust and corrosion. Replacing next week.