CAT C15 /6NZ trouble continues

Thanks for the input. The exhaust manifolds are now leak free after CAT replaced the entire manifold, twice. No noise there.
The "tick" is like a ball-pene hammer on hard steel, with a mild echo to it, just as a valve would sound i believe. There is also a Knock under load (which i have previously forgotten to mention). Today i toggled my cruise switch, bringing up flash code 36 and twice 46. Im getting conflicting info on the internet when seeking out the codes under CAT C-15 6NZ. CAn you or anyone confirm what these are please. Im finding code 46 as speed sensor, which makes sense as every time i cruise to a stop after exiting a fast road, or similar, and toggle the high/low range splitter (the black one) down, the speedo needle maxes out to the top, and drops down again , followed by a check engine flash on the instrument panel. But the flash code 36 im seeing; "low oil pressure warning" (my oil psi is 60 to 70 lbs depending ) and also "power supply to ECM low", which, if i understand correctly, there is 3 such power wires feeding the ECM, one from the battery my shop ran a dedicated new wire, fused at battery, about 3 weeks back, but the others are a mystery where they obtain power at...the fuse block at my left kick panel ?....The inframe high amp fuse by left steer tire may be another, or at the key switch ?... i dont really know. Any info on the flash codes and the power sources to ECM would be great.
Re the electronic noise on the surface of the engine is a good idea to remedy. Ill do that this weekend.
Greatly appreciated, beyond imagination !!!

 

i CHANGED ENGINE OIL WHEN I SERVICED TRUCK LAST WEEKEND. mORE THAN LIKELY WHY THE OIL PSI CODE CAME UP, AS SYSTEM PRIMED ITSELF , EVEN THOUGH I ALWAYS FILL OIL FILTER WITH OIL PRE SPINNINGIT BACKON. NOW THAT I THINK ABOUT IT, IT HAPPENED (CODE APPEARED) THE 2ND TO LAST SERVICE AGO.
OOPS, got typing not looking at the screen, i was in capitals.
Anyhoo, im going to put a 2 guage wire, battery negative to block of engine, and another wire from ECM to the 2 guage connection / junction, on block. Getter done tomorrow, Saturday. Also, truck ran absolutely premium tip-top today (with the exception of the engine clatter & knocking under the high end of the torque curve). Pulled stumble free, no chugging etc. Just had truck washed. Stumbled a bit for a few miles thereafter, but cleared up and all felt great.
Monday i have pre-op in morning, but back on the road thereafter, so ill let yall know how/if the ground addition faired by days end.
Surgery Tuesday, off for a while (a week or ??) so truck will be at local shop i use for odds and ends unrelated to my issue.
They have CAT ET program, so if anyone has any ideas related to the CATprogram, i can ask the shop to tackle it.
Thanks guys, greatly appreciate all your continued support.

 

Picked up truck this morning at CAT. They installed brand new ECM and programmed it (sad they had no test ECM at "ANY / EVERY "CAT locations i was at over past 18+ month's)
Anyway, I'm almost scarred to say, and seeing as I've said too much over the past 1 1/2 years, and it's been only a few hours with this brand new ECM, I'll let you know as soon as I'm satisfied of the results .
Regards:
307..