VP dashboard driving us crazy

[MapisM]

The IPS powered boat of a mate of mine is driving us nuts.
She has two independent fuel tanks, each with its sensor level. Consistently, on the dashboard there are two fuel gauges.
One day, out of the blue, the port one stopped working, with the needle stuck on zero.
Today, we opened some floor panels to access the tank sensors, figuring that it might be the faulty bit.
But nope, after swapping the connections of the two sensors, stbd gauge continued to show the level correctly (even when actually attached to port sensor), with port gauge not budging.
So, we moved on to the gauges, but with the very same result: port gauge, after swapping the connectors, resurrected (and stbd gauge did not move anymore).

Bottom line, it seems that all 4 components (2 sensors+2 gauges) work as they should individually, but the signal from the stbd tank to the dashboard gets lost in translation somewhere.
Otoh, the instruments are daisy chain connected (see pic below), so I guess that all signals are conveyed somewhere (engine ECU?) and converted into digital codes which are eventually sent to the dashboard.
So, should the system be checked with Vodia (assuming that it handles also non-engine specific data, though I have no clue about it), or can anyone think of further DIY diagnostic attempts that we could try?

TIA!

 

[Richard.C]

M,

Is it your understanding that the signals from the ECU go to the Tach then digital signals daisy chained to each gauge for that engine? Looks like it from the photo.

Have you isolated the tach to ensure there isn't an issue in sending the signal out to the gauges? So swap the main lines from ECU to tachs?

Looks like daisy chain ends in a blank plug for each loop? If so there maybe some terminating circuit/resistors in the plug, if there is have you tried swapping those?

 

[Portofino]

Sensor might have a modular unit somewhere.
Pulse Width Modulation -PMS saves miles of wires .
Sensor to modular unit to ECU to end user actuator / or in this case a gauge .
If it’s in the ECU then it sounds expensive.
Sometimes with the correct diagnostic tool ( Vodia? ) it’s tells you where the fault is . Can be just a software issue and a re- boot need but theses days with modern engines you are knackered without the lap top and dealer software.

Long shot disconnect the batteries wait 10 mins or overnight then re connect sometimes in cars the ECU ,s re- boot and the faults gone .

 

[MapisM]

See below in red...

M,

Is it your understanding that the signals from the ECU go to the Tach then digital signals daisy chained to each gauge for that engine?
Looks like it from the photo.
Yep, precisely.

Have you isolated the tach to ensure there isn't an issue in sending the signal out to the gauges? So swap the main lines from ECU to tachs?
Nope, but I see what you mean. We might give it a try the next time my mate will be onboard.
He just went back home due to work commitments - someone's got to keep the world economy spinning...
Looks like daisy chain ends in a blank plug for each loop? Yep
If so there maybe some terminating circuit/resistors in the plug, if there is have you tried swapping those?
nope, but all the instruments connected to the stbd tach daisy chain are fine.
It's only the fuel level that doesn't appear to receive any signal.
I suppose that a bad terminator would affect the whole daisy chain...

Worth trying anyway, together with the main tach lines.
Thanks a lot!

 

[MapisM]

theses days with modern engines you are knackered without the lap top and dealer software.

Indeed. This is one characteristic of modern engines which I hate with a passion, I have to say.
Disconnecting current from everything is an intriguing suggestion, but knowing that chap and what he keeps stored in onboard fridges, I guess he would rather live with a dead tank level till the end of the season.....

 

[julians]

Try changing the order of the daisy chaining, ie put the fuel gauge closer to the rev counter.

 

[MapisM]

It would be funny if this trick should work, considering that the instrument worked fine till not long ago...
Yet another attempt to add to the previous list, anyway! :encouragement:

 

[julians]

My wild stab in the dark guess is that it is the instrument (or maybe one of any of the instruments upstream) upstream from the fuel gauge that has the problem, so by putting the fuel gauge directly after the rev counter you eliminate/prove my theory.

 

[julians]

An variation on my theme is that it could be the rev counter itself that is failed, so maybe you should also try swapping the rev counters over as well.

 

[Ratkins]

Ha similar issue with our ips boat, all the cables from dash including ignition ips joystick go to throttle assembly which has its own ecu (helm control unit), from here they go to engine is it only fuel playing up or tachometer as well etc. Maybe lift out throttle assembly and sway cables over they were identified on ours Might help confirm cause or hopefully confirm it’s not the hcu

 

[MapisM]

We didn't trace the main cable connected to the tacho.
I said before that I guessed it came from the ECU, but it makes sense that also the throttle assembly is involved in the chain, so to speak.

Re your question, it's just the fuel playing up, and just on one side.
Btw, the two tanks are normally connected, so having one of the two gauges working is actually enough.
And 'fiuaskme, I'd rather have sight gauges than redundant dash gauges.
But I can see why my mate wants to see all instruments working as supposed to (and actually used to, till recently).

 

[BartW]

there are somewhere 2 x grey box,
interconnection between the gauges, and the engine ECu's, and all controll panels, (at least on a pair of D3's
have you found the sensor cables going to these boxes ?
have you tried swapping these cables on the box side ? maybe faulty connection, / loose connector on that side ?


tell Enzo to relax and enjoy summer instead of worrying about a redundant gauge ;-)

 

[MapisM]

Haha, as if you would just relax and do nothing, when you are onboard BA!

PS: nope, we didn't try any other swaps aside from gauges+sensor tanks. That will join the list of next attempts! :encouragement: