Volvo D2-40 will not turn on

[rickpalm]

I've got a problem with a Volvo D2-40 that I could use some help on.
About two weeks ago we returned to the dock and the engine would not shut down. Stopped the engine using the control arm on the engine. When I checked to see if it would start up I found the engine control panel would not turn on.
Came back to the boat to troubleshoot and the panel turned on and the engine started up. Repeated several times and all worked well.
Next time at the boat and the engine panel would not turn on. It's not that the engine wold not start but that the panel does not turn on to allow a start.
Troubleshooting and replace parts:
We have had the problem with the engine panel before so I swapped it with an new one. No change
Swapped the engine computer box with a new one. No change
I have 12.8V at the battery and all the way to the computer and starter motor connection.
All fuses in the circuit are good and tested.
Removed and checked engine ground all clean and bright connections.
Checked all connections to sensors and oil pressure switches. They look good with all pins clean no visible corrosion.
I suspect a sensor has gone bad and that brings me to the point of asking has anyone run into this problem and is there a test set I can buy to check the engine for a fault. Swapping sensors does not seem like a good idea.
Thanks for the help.

[catmancan2]

I had the same D2-40 problem on a Catana 47, no power to the stb start engine and ECM bayonet fuse was OK . Removed port ECM and connected to stb engine like I think you did and all was fine with panel/tack/engine. So ordered 2 new ECMs so I have one as a back up. Might be time to get a VP tech in the loop?

[catmancan2]

I should have added, I don't know why a bad sensor would prevent having at least power to the engine panel?

[rickpalm]

Thanks Catmancan2 for your reply.

We found the problem yesterday and it turned out to be a lose connector on the extension cable from the engine panel to the port engine. We hooked up the control panel directly to the computer and it turned on right a way.
Next we checked for continuity of the cable from the engine panel to the engine and found two wires open. Running down the cable looking for a place where two wires could have been chafed through I ran into the lose connector joining two extension cables each 22.5ft long.
Fortunately, that fixed the problem.

[catmancan2]

Fantastic, you saved $600 not buying a new ECM and earned yourself extra Rum!