97 Cummins 12v Trans Fault help
 

THE TRUCK HAS LOST OVERDRIVE AND THE TRANSMISSION TEMP LIGHT IS ON... THE TEMP SENSOR WAS REPLACED BUT DIDNT REMOVE THE LIGHTS. HAD THE TRUCK PLUGGED IN AND FAULT CODE P1765 CAME UP. WHICH IS: TRANSMISSION 12 VOLT SUPPLY RELAY CONTROL CIRCUIT. I HAD A LOOK MYSELF AND SWAPPED RELAYS CHECKED FUSES AND PLUGS TO NO SUCCESS.

ANY IDEA WHAT COULD BE WRONG