Volvo Tach and Speedometer Stopped Working

[Peace42]

I replaced the two transmission speed sensors, crankshaft and camshaft sensor yesterday. The problems still occurring. Before the problem started happening i had a CV Axle and 2 back wheel bearings installed on the vehicle. After switching the sensors and seeing it still did not work, for the hell of it tried pulling the back ABS wheel bearing sensors from under the back seats. Turned the car on still the same problem. However there is another cable behind the driver side rear seats next to the Back Left ABS sensor. I pulled this cable and everything works fine. However i dont know what this cable is or how to find a replacement / the suspected bad part. Could someone point me in the right direction of what this cable is? I have attached a picture.

EDIT : sorry if some of this doesnt make sense or if more information is needed. If this is the case just let me know. Im trying to get to the bottom of why my speedo and tach stopped working. The engine temp gauge and tach start with the car with the wire in the picture attached then after about 1 minute of the car being on they drop to 0 and never engage again until i turn the car off and back on. If i turn the car on with the wire in the picture unplugged the speedo, tach, and temp gauge atleast read properly but seem a little slower than usual to move.