I made a 3 foot long jumper wire with alligator clips on each end. I used 14 gauge silicone hookup wire because it is very flexible. I have been trouble shooting the temp sensors on my flathead V8 (8BA) motor. Just jumpered across each wire between the two sensors, and each wire going to the gauge to check continuity, then check the temp gauge to see if any change occurs. Then I grounded the temp gauge to make sure it went all the way to "cold" then took off the jumper and it returned to "Hot" (with the ignition switch on) to verify that the gauge is working.

Sometimes simpler is better.