Idea is for cable to pull emergency breakaway switch pin OUT should trailer become unhitched from truck and umbilical cord has been pulled out.
Chains should HOLD/Catch trailer tongue.....that is why cable should not be wrapped/tied/woven thru chains because pin would not be pull unless chains broke.
Cable should be just longer than umbilical cord and shorter than chains
Tie wrapped to umbilical cord and then connected to receiver works.
And YES.emergency switch pin should be pulled to test emergency brake circuit/function CAUTION: Umbilical cord should be unplugged as some brake controllers don't like the FULL Trailer Battery Voltage backfeed that can occur
