Df300 motor wiring harness replacement

[La0306]

I have a 2008 Df300 , I have 485 hours on it , I love this engine have had no major problems until now , have always done the regular maintaince schedule on it.
Well here is what happen , ran fine all day then the next day i started it in the boat stall ran for about 12 to 15 seconds and died , tried to start it again but couldn't because it threw all kind of fault codes , I got rid of the others codes the only one I couldn't was the 4-2 , so I ordered a new one CKP sensor and replaced it . same thing ,fault code 4-2 still exist . And engine will not try to start.
So I took it to the dealer , he got the motor started but it was still throwing the 4-2 code , he said in the last year , motors ranging from 2007-2016 models df300 only that he has worked on 4 of them came in and doing the same thing , that engine wiring harness had to be replaced .
Just trying to see if y'all have some input or advice to check anything else . As I find it hard believe it's time to replace the wiring harness , but I could be wrong
Any help greatly appreciated
Thanks

[redlowrey]

This is only the start of problems to come, communication between modules ecms bcms and so on, can bus lines high speed communication, Salt air, salt water, moisture between connectors, I think you would not have to change wiring looms, you just need the right technicians finding the problems.

[redlowrey]

I should of added, what where the other fault codes, and what did the dealer do to get it started. Sounds like a communication error between the bcm and the ecu, the engine is running so obviously it must be receiving a crank signal.

[La0306]

There were other codes when they got it started , 3-2 , 7-2 or 7-3 . So it looks basically boiling down to connectors because of corrosion? What would be your best recommendation , as the dealer wants to replace the whole wiring harness . Which I don't agree with .Check every connection from the bcm to the ecm and all other sensor connections ?

[redlowrey]

Mate I would disconnect the wiring plugs and spray electrical cleaner in all of them and the ecu and bcm , I think myself the problem is in your can bus lines, communication between your ecu and bcm. You need a wiring schematic so you can check all your powers and grounds and your can bus lines ext. How is it when they changed the looms they fixed the problem, more like when they disconnected the plugs they fixed the bad connection. When it wouldn't start did you check the crank sensor too see if it was switching. good luck.

[La0306]

Found the problem, but how to solve it!!!!

Hey i clean all the connections with cleaner and re hooked them back up and tried starting it every time after cleaning each connection from the each to
The Bcu with no luck. But I FOUND The problem in the FUSE BOX , I replaced the fuses last year expect for the relays , so I went ahead replaced relays as well this time and fuses , but There is loose connections or
Corrosion in the spades connectors , you can here the relays clicking as you touch the relay with a little pressure ,I use electrical cleaner and electrical grease but still not making good connection, . How can i take the fuse box apart with out tearing it up as you can not buy a fuse box only you have to buy whole wiring harness . I don't mind buying special tools. For recrimping the spade terminals. What would you do? They had to assemble at the factory some how. is there plastic tabs to take it apart or did they sonic weld them in place?