Steyr 12M18 service manual?

I agree with Greg. My 16’ Unicat is from the last generation, lots of electronics but not interlinked. No failure in 12 yr/100k mi except 1 out of 2 Sterling battery to battery chargers. I assume that they provide wiring diagrams and component manuals. If so things are easy.
It’s ironic that you have an advanced electronic camper albeit with lots of redundancy and a totally optimized non-electronic chassis. No chance for electronics failure there!
I had the good luck to buy a chassis (the last year) that runs on high sulfur diesel and easily disconnected EGR.
No problem with the multiple computers but only with the “HD” alternator which I eventually replaced with a 28si 200A Delco. One of the biggest advantages of the computers is the automatic shifting 8 spd trans, easy on my mangled right hand and great in city traffic. It takes 3 interacting computers to run it but I have spares and there is a manual backup.
Don’t be afraid of electronics when the system is well designed and has quality components, which I think applies to Bliss.
Congrats on the Steyr!!! I was on the fence 2yrs ago on either the 12M18 or some type of SBU Unimog for a simple build-out camper. I finally decided on the latter due to parts availability...especially here in the states. We'll have to get together sometime for a beer. The wife works bi-coastal in Santa Cruz/St Augustine so I travel with sometimes...projects permitting. Try the guys over @ for a service manual. Great bunch of guys and are Steyr fanatics. Good luck.
I just got back from a two day training session at the Bliss HQ in Breda (they require training to gain access to their manuals database and warranty). They definitely have their act together. The training was well planned out, simple to follow, and provided enough time to dive deeper into personal areas of interest.

My area of particular interest were the electronics. While I still have concerns about the useful life and durability of the integrated electronics, I was happy to find that the major components all have manual overrides and are easily accessible when the needs arise.

I would place their build quality as high second tier behind Unicat, but ahead of builders like Krug and BiMobil. Having purchased a used box, I was curious to see what issues arose for the previous owner. All appeared to be minor (failed solar vent, a cracked storage box mount, and torn mosquito net). Other than some odd modifications made by the previous owner, about all I could find for remaining issues were a couple of slightly warped cabinet doors that require a bit more force to engage the positive locking latches and the rear rack is a bit temperamental to use. Bliss is aware of those, but it’s unclear whether they will do anything should the issues get worse. I’ll keep an eye on those and report back.

The Excap is an amazing truck. Stefan has done an excellent job of breathing new life into the Steyr 12M18. Mine is a Doka and the design of the additional rear space is brilliant in my opinion. For my needs, the chassis availibility in the USA was the weak link. I spent a few years looking at Unimog U500s, 2450s and 1550s, LMTV 1098s and briefly owned a Fuso before moving on to the Steyr. Hopefully, parts won’t be too much of an issue since Excap has access to pretty much anything I might need. There are a few modifications I’m looking into making down the road: stiffer springs, slightly smaller tires/re-gearing the differentials, and installing an exhaust brake.