2000 toyota camry speedometer not working?

2000 Toyota Camry speedometer quit working had the codes pulled and it was P0500. Changed out the speed sensor still not working. Changed out a wheel sensor still no luck. Did a soft reset on the ECU it started working but stop again after a few weeks. Did a soft reset on the ECU and it started working again. Does anyone have any idea what I need to do to fix this problem?