Re-engineering the Grand California 680 – from OEM compromise to a coherent, integrated system

[Bizzaru]

Audio / Music system – my favorite part of the build 

 

Again red is testing.

 

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[Bizzaru]

Cameras

The camera system was upgraded with a focus on image quality and real usability, not just basic functionality.

Rear camera (reverse):
The original camera inside the OEM housing was replaced with an AHD 1080p camera, keeping the original mounting bracket. This preserves the OEM look while significantly improving image clarity on the large display.

Drain camera (underbody):
An additional AHD 1080p camera was installed underneath the vehicle to monitor the grey-water drain area.
The camera includes IR LEDs, allowing clear visibility even at night, which makes emptying the tank much easier and more precise.

Both cameras integrate cleanly into the system and provide reliable, high-resolution images in real-world use.

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[Bizzaru]

Water system air compressor 

The water system was redesigned with a focus on reliability, winter usability and proper integration into the vehicle control logic.

Water pump:

• The original pump was replaced and is now fully controlled via KFG. This allows clean integration into the vehicle logic instead of relying on standalone switches.

Kitchen faucet integration:

• The kitchen faucet was replaced with a new hot/cold unit. Since the new faucet does not include a micro switch, the pump control was rerouted through a custom control board developed by us. As a result, the water pump can now be switched ON/OFF directly from my custom app, in addition to the standard control logic.

Grey-water tank:

• The tank is insulated using Armaflex. Because this material can be damaged easily by stones or debris, I added a lightweight aluminum skid plate for mechanical protection.

Winter operation:

• The grey-water tank is equipped with a heating pad, and the electric drain valve is fully integrated into the system, allowing controlled and reliable emptying even in cold conditions.

Even with relatively few visible components, this setup significantly improves usability, especially in winter and off-grid situations. 

 

Air compressor

 

The compressor is mounted on the front longitudinal frame member.

Existing factory holes were used, allowing us to fabricate a custom stainless-steel bracket without drilling new holes in the chassis.

The bracket keeps the compressor rigidly fixed, protected from vibration and movement.

The air intake filter can be accessed and cleaned from the engine bay.
For full service access, the inner fender liner (plastic wheel arch protection) needs to be removed,a compromise between accessibility and protected mounting.

The compressor is used for:

• rear air suspension bags
• a dedicated external air outlet, allowing me to inflate tires and other equipment when needed

This setup adds a lot of practical flexibility, especially when traveling off-road or adjusting vehicle load, while remaining fully integrated and protected.

 

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[Bizzaru]

Awning

 

The OEM awning was one of those details that kept bothering me — simply because it looked too short for the vehicle. Visually, it never really matched the proportions of the Grand California.

So I replaced it with an awning that actually fits the length of the van properly.
This alone improved the overall look a lot.

For the new awning I chose an electric model. The weight difference compared to a manual version is minimal, but the comfort gain is noticeable.

The awning can be operated:

• via a physical button
• and via the custom app we developed

This keeps it consistent with the rest of the control philosophy: simple, integrated and easy to use.

 

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[Bizzaru]

Toilet & bathroom

 

There isn’t a lot to say here, as most people are already familiar with the Clesana C1.

The integration itself went relatively smoothly, with only a few components needing to be reworked to fit cleanly into the existing space. The result is a system without chemicals and without unpleasant smells.

The former cassette compartment was repurposed:

• a custom insulating insert was made
• the space is now used to store a hose, keeping everything tidy and accessible

A few small but important usability improvements were also added:

• The original motion sensor was removed and replaced with a dedicated bathroom light switch.
• If the light is accidentally left on, it can be switched off remotely via the app.
• The bathroom roof hatch was replaced with a new, quieter model, reducing driving noise.
• The new hatch also includes a ventilation fan, improving airflow when needed.

For all these modifications, the required wiring was installed properly, sized for the actual power consumption and future use, not added as an afterthought.

Overall, these changes may be subtle, but they significantly improve everyday comfort and usability.

 

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Bearbeitet vor 2 Stunden von Bizzaru

[Bizzaru]

Connectivity

 

Connectivity was designed with redundancy and real-world performance in mind.

The main system is a 5G router with dual SIM support, including eSIM capability, allowing flexible provider selection and reliable mobile data access while traveling.

The router is paired with a dedicated external 5G antenna, permanently mounted on the vehicle. Antenna quality and placement make a significant difference, especially outside urban areas.

I ran multiple real-world speed tests, comparing a smartphone and the 5G router, both connected to the same mobile provider under identical conditions:

• the router is typically 10–15% faster than the phone
• in areas with weaker signal, the performance gap becomes significantly larger, with the router maintaining usable speeds where the phone struggles
• In addition to mobile data, a Starlink system is installed for locations without 4G/5G coverage.

The Starlink antenna is mounted inside the vehicle, securely fixed to the fiberglass roof.

Despite being mounted indoors, the fiberglass roof does not noticeably affect reception. Any signal loss is negligible in real-world use and outweighed by the benefits of a fully protected and theft-safe installation.

Together, the 5G router, external antenna and Starlink provide a fast, stable and resilient connectivity setup, suitable for both travel and remote work.

 

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[sonnyboy]

Your project is highly ambitious and addresses most of the problem areas of our GC. I find your implementation so far very well executed and extremely professional. 👍
 

I do have a question regarding the additional alternator you plan to install. Since I have a very large battery capacity (990 Ah) in my vehicle, I have also looked into such an option. Do you have any information on whether a second alternator can be installed on the engine used in our GCs? I know that this option does or did exist for the Sprinter.

One more suggestion, since you have practically disassembled the entire vehicle anyway: If I were in your position, I would also renew the seal between the fiberglass roof and the bodywork, as the factory seal tends to become leaky over time on many GCs. 

In any case, I’ve subscribed to your thread and will be following along with great interest. 😊

 

With best regards

Marcel

Bearbeitet vor 2 Stunden von sonnyboy

[Bizzaru]

Heating & air distribution

 

Unfortunately, this is one of those areas where there aren’t many “nice” photos to show — simply because most of the work happens behind furniture and panels.
That said, this was one of the most time-consuming and technically involved parts of the project.

After carefully reading the Truma Combi installation manual, it became clear that the OEM installation by VW does not follow Truma’s own recommended installation procedure.

 

Base concept

The Truma Combi has four hot air outlets.
In my setup, three are actively used, following the logic described by Truma:

• Two outlets are used for the front area and the bathroom
• The third outlet, which provides a higher air flow, is dedicated entirely to the rear section

This alone already changes how heat is distributed through the van.

 

Airflow to the rear – removing the main bottleneck

The OEM hot air duct leading to the rear was a major restriction.

• The original 60 mm ducting was replaced with 90 mm ducting
• This ensures unrestricted airflow and significantly reduces pressure loss

The main rear airflow was also rerouted higher up, secured along the structure of the mobile shower housing. This keeps the ducting efficient while freeing space below.

 

Mid-section & lower area heating

In the middle of the van, near the battery compartment, I added an additional hot air outlet.
This helps distribute warm air in the lower central area, which was previously noticeably cold.

The ducting towards the water tank area was also redesigned:

• a 45 mm duct was routed further to the rear
• a low-position hot air outlet was added
• this outlet sits close to the air compressor coupling, helping keep that area warm as well

Furniture & sleeping area heating

Behind the rear furniture, I integrated a perforated 20 mm duct, running along the back.
This creates a gentle, evenly distributed heat output that helps warm the sleeping area without creating hot spots.

To improve comfort during the night, I relocated the temperature sensors to the sleeping area.
For me, it’s more important that the temperature is well controlled where I sleep, rather than at the front of the vehicle.

 

Design, testing & measurement

A significant amount of time went into:

• airflow calculations
• testing different duct diameters
• designing and printing custom Y-connectors to balance airflow correctly

Many iterations were tested and measured.
Unfortunately, I only have photos from different development stages, not always the final configuration — but the end result is what matters.

 

Result

The result is a heating system that:

• follows Truma’s installation logic
• delivers even heat front to rear
• eliminates cold zones, especially at floor level
• provides stable night-time comfort in the sleeping area

This was not a “bolt-on” change, but a complete rethink of airflow and distribution, and it made a dramatic difference in winter usability.

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[Bizzaru]

Heating & air distribution

 

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[Bizzaru]

Technical approach

 

Throughout the project, the goal was always to minimize permanent changes to the vehicle. Wherever possible, existing structures and mounting points were used.

That said, there are a few areas where drilling or enlarging openings was unavoidable in order to achieve a clean and functional integration.

One example is the former gas ventilation opening.
This opening was repurposed to route:

• electrical cables
• the compressed air hose from the onboard compressor

Instead of improvising, custom parts were designed and manufactured specifically for this purpose. These parts ensure:

• proper sealing
• good thermal insulation
• mechanical protection
• a clean, OEM-like finish

All modified areas were carefully protected and sealed, with durability and long-term reliability in mind.

I’ll attach a few photos as examples to show how these solutions were implemented in practice.

 

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[Bizzaru]

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Hi Marcel,

 

thank you very much for the kind words — I really appreciate the feedback. 👍
It’s great to hear that the approach and execution resonate with you.

 

Regarding the secondary alternator:
In my case, the alternator is a custom-made solution, developed specifically for my setup. I managed to connect EcoFlow directly with the company developing the alternator and its control electronics, so the entire system is designed as a coherent package.

The key point is that the alternator control is handled directly by EcoFlow, not by a standalone regulator. This allows proper load management and integration with the EcoFlow Power Kit without stressing the engine or electrical system.

 

From an installation perspective, the plan follows VW’s own guidelines for a secondary alternator. So mechanically and structurally, it’s aligned with how VW intended such an option to be implemented, even if it’s rarely used in practice on the GC.

Just two days ago the alternator finally arrived, I’ve been waiting for it for almost six months. I haven’t started the installation yet, so for now I can’t share real-world results, but once it’s installed and tested, I’ll definitely report back with data and observations.

R

egarding your suggestion about the fiberglass roof seal: that’s a very valid point. I’m aware of the long-term sealing issues on many GCs, and it’s something I’ve kept in mind throughout the project. For now, I haven’t touched that area yet, but it’s certainly on the list for future inspection and potential preventive work.

 

Thanks again for following the thread, I’m glad to have you along, and I’m happy to exchange experiences as the project moves forward.

 

Best regards,
Razvan

[Bizzaru]

Since I’ve posted quite a lot today, I’ll pause for a bit and see if there is real interest in the project.
If so, I’ll continue with more detailed technical posts.

For now, I’ll just leave a few photos without detailed explanations.

One last thing I don’t want to forget to mention today:
I also reworked the bed frame, so it can now be folded, giving me enough space to move around and access the cabinets properly when the bed is not in use.

I’ll attach a photo as an example.

 

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[Bizzaru]

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[Bizzaru]

The van was finished at the end of June, with only a few minor fine-tuning details left to complete.

Since then, it has been intentionally tested in real conditions:

• off-grid at the seaside in extreme heat
• heavy torrential rain
• left standing at –10 °C
• and thoroughly washed with a high-pressure washer

All of this was done deliberately, to make sure there are no water leaks and no weak points.

Every time I installed something with a potential risk of leakage, I tested it with water two or three times, not just once.

I’ll be honest: when installing the new bathroom roof hatch, I initially had a small leak.
It showed up during testing, exactly as intended. I then:

• replaced the original butyl cord with a more suitable one
• and applied a UV-resistant Sika sealant on top

After that, the issue was completely resolved.

These tests gave me confidence that the van is now weather-tight and reliable, not just in theory, but in real-world use.

[Slowmover]

Hey,

 

great project and an awful lot of work!

 

i wonder if there are some pics showing your starlink antenna intallation?