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The Doomsday box came about for two reasons. The first is because the MDI box on Volvo D Series are notoriously unreliable and the second reason, I'm pretty sure, is so Mads could have a box on the boat and call it the "Doomsday box" ;)

There is an MDI box on Volvo D Series engines (Mechanical Diesel Interface). The MDI box connects instruments from the cockpit to the engine. Also, it measures oil pressure and temperature, two things that are very important to know, as I've been told. It's a great little thing that allows us to monitor and know exactly what's going on with the engine. However, it's great when the MDI box is working and has not failed. As I mentioned above, the MDI box on the Volvo D series has a reputation for dying, which happened to us this summer before leaving Denmark. We were perplexed and did not know how the failure occurred. We suspected liquid damage, but the connectors were dry when Mads inspected it. Even though we were clueless about why it was not working, we still had to scramble to find a new box before we left. Luckily, we could still start the engine without the MDI box. However, that involved using a screwdriver to turn the engine on, which would not be easy in any sea state. Not ideal for the long run, and that also meant no oil pressure or temperature monitoring.

Getting a new box was difficult. MDI boxes are expensive, around $600.00, and because of supply chain issues due to the pandemic, MDI boxes were nearly impossible to find. Then, after many google searches, emails, and phone calls later, we finally found one in Sweden. We were grateful to have found one but did not want to be again in that situation. Thus, the creation of the Doomsday Box.

We can start the engine with our new spiffy box and monitor it if the MDI box dies. Plus, the Doomsday box makes Athena feel more like a spaceship. Win-win for everyone ;)

In this Video

Doomsday Box Supples:

Box Wiring Diagram:

Double Relays: Part: 42-145

Adaptor Plate:

Oil Pressure Switch:

Temperature Controller:


Engine Start Button:

Red Switch:

Light Switch:

  • I just removed the red cover from the red switch above ;)

Black Box:

100 AMP Relay:

Oil Pump:

Mads Tools:

Oscillating Multi-tool Tool

Bosch Circular Hand Saw

Bosch 150 Turbo Sander:

Bosch Drill and Impact Driver:

Makita Jigsaw:

Bosch Router:

Camera Gear:

Sony A7C:

Tamron 17-28mm f/2.8 Lens:

Go Pro Hero 9:

Sony Z-V1:

Sony GP-VPT2BT Handgrip for Sony Z-V1:

Wireless Microphones:

Manfrotto 290 Xtra Aluminum Tripod:


Mar 28, 2023

I am doing this on my 2x 2014 D2-40's on my catamaran as full backups to the MDI and Volvo Control panel with the ultimate goal of utterly removing the MDIs and going to relays and gauges. So on the Oil pressure plate I also ordered a fluid gauge in the 0-100 supporting the Volvo 30-70PSI oil pressure range. -- Stephen SV Flying Tigress


André Albuquerque
André Albuquerque
Aug 09, 2022

Hey there, what alternator brain box did you use?


T Aksoy
T Aksoy
Feb 28, 2022

Hi. Spelling : Volvo mispelled in the title ;)

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