Volvo D2-55 MDI Units

[Craig Conlon]

Hi guys,

I’m brand new to this forum not used them very much but I’ve just purchased a new awesome Lightwave 45 cat that is fitted with Volvo D2-55 engines. One engine has actually started itself on two occasions and when the first took delivery would not start at all until I fiddled around with it but I’m not sure what I did to get it started but eventually I got it started.

Now as soon as you push the ON button to activate the LCD and diagnostics it starts. Sometimes!

I understand there has been lots of issues with these units and there was a recall in 2017/18 but now Volvo are saying electrical components are out of warranty but it is is just downright dangerous.

Has anyone had the same experience and did Volvo rectify the situation?

[tkeithlu]

Welcome to the forum, Craig.

I suspect that you've got a starter relay wired to the "on" switch to the panel. Somehow a signal (voltage) is getting to the starter solenoid when you are in the "on" position. I'm also concerned that it may be running the starter continuously.

Go the the starter on that engine and trace backwards. If need be, disconnect the heavy positive lead to the starter, turn on the panel, and see if you get a voltage with your multimeter. Trace that voltage back to the panel. You may find that the lead for starting is on the "on" pole of the "ignition" switch rather than on the "start" pole. You might also find that "on" is connected to the starter circuit farther down, perhaps even at the starter solenoid.

Welcome to the world of tracing DC circuits. It can be fun, and it can be frustrating.

[Craig Conlon]

Hi

Thank you for your reply Volvo ended up coming to the party and have replaced both MDIs and the problem is rectified, there was some discoloration in the start terminal which indicates it may have held in when the engine was running but it appears to be corrected now.
Lucky I am a sparky so fault finding and circuit tracing are in my trade, this was a straight out product failure but at least it’s sorted and hopefully will not return as Volvo have changed or modified these components

[HR42]

MDI’s on that generation of Volvo engine were a disaster. I have a d2 75 installed in 2016. I forget how many replacements they threw my way. Eventually one worked. The company that commissioned the engine even did a parallel wiring job bypassing the MDI altogether. No tacho, engine diagnostics etc but at least when I ran out of MDI’s I could start the thing

A popular you tube catamaran channel running the same generation had the problem too I think

[Craig Conlon]

I have had the latest updated time installed yesterday so time will tell if the have modified them or just changed part numbers. I have details on the bypass switch and I will be installing them for piece of mind and we have a spare MDI on board. Thanks for your feedback