Check for a good ground. They are usually grounded through one of the mounting screws onto the frame - often with a "star" washer under the flange to help make a good connection. Either take out the mounting bolts and clean up where the mounting flange touches the frame, or run a ground wire directly from a bolt on the motor head to the frame or battery.....
Bill & Kate - Stone Harbor, NJ
w/ Bailey (standard poodle) and Zeke (partipoodle)- both rescues
2018 Ford F-250 Super Duty Crew Cab w/ 6.2L gasser
2014 Forest River Wildcat 272RLX fifth wheel