Repairing a Motorhome Thetford Toilet SOG Unit without Breaking the Bank

We fitted a ‘SOG Unit’ to our motorhome’s Thetford cassette toilet about four years ago (more details about how we fitted ours here), enabling us to stop using chemicals in the loo, and to empty black waste into sensitive rural toilets in Scandinavia and the Baltic states. The system broke recently, and this post quickly looks at the repair.

What is a SOG unit?

The SOG system costs about £170 and is pretty simple:

• It has a small fan fitted to the toilet door.
• The fan is connected with a flexible pipe to a special attachment on the cassette.
• When you open the blade to the loo, a small switch closes and starts the fan.
• The fan pulls air from inside the van through the loo and pushes it outside through a charcoal filter to cut down on any nasty whiffs.

This video shows how to install the kit yourself:

SOG repair without breaking the bank

Our system’s worked perfectly for these past four years. Inside the van we get next to no smell, and in our opinion the SOG works much better at whiff control than chemicals or using washing liquid etc. However on our latest tour our SOG went doolally and the fan only worked every now and again. As soon as the fan stopped working, the smell came, both re-enforcing how good the system works and getting us straight to the campsite shop to buy some blue!

A bit of investigation with our multi-meter revealed the micro-switch was faulty. This is attached to the inside of the toilet housing and switches the fan on when the blade is opened (the above video shows this). Our micro-switch had gotten wet more than once due to a faulty flush mechanism on our van, and was showing signs of corrosion.

We opted to use chemicals for the remaining couple of weeks on our trip. When we got home we looked into the cost of replacement parts, giving us these options:

• Option 1: buy a replacement switch from SOG (£8.45), and a soldering iron kit to re-connect it (£8.99). Total cost: £17.44
• Option 2: same as Option 1 but get the switch from eBay (£3.14 plus £8.99). Total cost: £12.13
• Option 3: buy the switch and wiring loom from SOG, avoiding the need to solder anything (£32.08). Total cost: £32.08

None of the options are massively expensive, and most of the cost of the repair would be for labour if we took it to a dealer to fix. I’m comfortable using a soldering iron, and the one we got is only 60W so runs from our 300W inverter and meant I could do the repair at the storage location where this is no mains power. If I wasn’t comfortable with using solder, Option 3 would be quite simple to do – the hardest part being getting the old switch bracket and cable loom attachments off using a flexible knife.

A few photos from the repair job:

And that’s it. Total cost: £12.13, the system is working 100%, and we’ve now got the soldering iron kit for any future repairs. Jobsa goodun!

Cheers, Jay