Serial number is 1a3100560. Found on heat exchanger. More tests. In gear switch on motor has 5V on ylw/pnk always but blk/ylw has 12v with key in crank position. If a ground is provided to blk/ylw it fires starter relay and starts and runs. 5v on ylw/pnk doesnt provide ground ever. That wire goes directly to harnessA on computer. Blk/ylw goes to start relay. I would think computer would control ground to allow cranking but why 5v on wire? Is my 10-14 adapter wrong for this engine? Is a transom harness with steering sensors and trim control necessary on this application? Few dealers and boat shops called locally have no clue. Nearest boat shops to me dont even have 555 adapter for their scan tool. Hicksville here. Anyone want to sell me a rinda with adapter? Going to run a 17 prop so I can take family out. Boat will run 30 mph like this for now. When asked what engine I say 4.3 not 496 when on water.

When you did the vessel view did you put the correct terminator on it? I had to buy one for my vessel view as it wasn't on my boat. Until I did that, it wouldn't find the PCM.

Is there more than one type? It already had one and that is where I plugged in vesselview and installed terminator on vesselview harness. Check resistance of terminator and it makes connection to join pins.

Well, what color was the one that was installed? I had a cover but not a terminator. I had to buy one. I think the "cover" was purple and the terminator I bought was yellow. I just had a similar problem to you where it wouldn't find the PCM and that was the issue. Hope that helps.

Cover is yellow and I believe it says terminator on it, but will check to make sure. Thanks for the input.

rinda scanner found
 

Scanned engine and repeated codes for pitot sender and fuel level codes, all there as it isnt wired for them. Does this 08 motor need transom harness hooked up and wired to operate properly? Need to water test with scanner still. Still cant find reason why no crank unless I ground 1 side of in gear senor unless that is affected by transom harness as well. No other codes and all pcm and static tests all pass.

Water test done
 

Went out with scanner and all tests and parameters pass. Engine is 100% power available all the time. 42lbs fuel pressure under load. Water pressure at 24 lbs. Ran the original 17 3 blade stainless the alpha setup used to run and boat ran 52 mph @4800 WOT. Seems a little wimpy for a 496 HO in a 23 foot runabout. Engine scan showed much higher hours than was told when I bought engine. 938 after today. Most below 3000 rpm. Is this engine in need of some freshening up? It runs nice and smooth, no smoke and has good compression(170psi) on all cylinders. Anything I can do to get any performance out of her as is or is it rebuild time? I have a spare running 8.1 truck motor I could build as long block to replace this one with and swap but not this summer. Is thru hull exhaust necessary with this engine and maybe that is contributing factor? Install manual I found online says not recommended to just do prop exhaust except in Europe where thru hull not legal. I have merc diverters and compressor, just need to find some side exhaust tips to install.