2003 240 Sundeck Smartcraft problems!

[rv8tor]

I have a 2003 240 Sundeck and I have been having Mercruiser Smartcraft issues. It started last year when my Smartcraft guage begin sending erroneous messages to the other guages. The fuel guage was all over the place, the tach and speedometer began moving together from zero to max and then back again, and would then oscillate back and forth together. Also, all these crazy readings were running across the display on the Smartcraft guage itself! The drive trim also was also inaccurate. Mind you the speedometer hasn't worked at all since I bought the boat 5 years ago. This is the first time I've seen that needle move at all! One other thing is that it doesn't matter whether the engine is running or not! After asking around at the marina but before just having a mechanic take a look at it, I decided to just replace it.

Ordered one online that also came with the wiring harness. Replaced just the Smartcraft guage and everything now worked! That was 6 months ago. Several days ago, it began doing all the same things again! ...with a brand new Smartcraft guage no less!! So now I'm thinking that perhaps the problem is in the harness somewhere or somewhere else on the boat.

I figure since I have this new harness sitting in my toolbox raring to go, that I would go ahead and replace it. Seems easy enough, except I can't find the Smartcraft junction box to plug the other end of the 10 pin connector into! As best as I can tell, it is not behind the instrument cluster in that area, although there are a number of wires and other harnesses back there. I've looked all through there and I can't find it!!

Can any of you familiar with this help me on this??

Thanks in advance!

Jeff

 

[Leardriver]

Every problem I have ever had with a gauge on a boat was due to a poor ground, which is a constant boat thing.

 

[Boatech]

Depending on how yours is wired it may not have a jbox. Some have the Main harness from the engine goes straight to the gauge with a pigtail for the system link gauges. Check all your wire connections. Try unplugging each link gauge one at a time and see if the issues go away.