got a 2 channel lab scope handy? if so let me know and I will gladly walk you threw how to really test cmp/ckp concerns.
If not I would suggest ohming out the cmp and ckp circuits.. if they test good move on to a load test. if all that passed let me know.
IMO another harness issue.
cmp and ckp circuits are shielded and not really repairable even if you were lucky enugh to find the open