Inside Saab – electrical integration

File this under “Things that blow your mind about how incredibly complex it is to design and build a motor vehicle”. Long title, I know. But this is one of the more mind-blowing insights I’ve had into the vehicle development process since being here at Saab.

I’ve told people for some time now that there are no ‘fingersnap’ solutions when it comes to building/changing automobiles. It’s an incredibly complex process and whilst the evolution of electronics has given us many advances in vehicle functionality, behaviour and performance, the development work required to produce these advances is astounding. Add in the fact that everything you’re about to read has to be developed, tested and approved for all of Saab’s global markets, in all vehicle configurations, and you can get a sense of the complexity even before you start trying to calculate the permutations.

I’m going to apologise in advance for this one. There’s no way that I could adequately gather together everything I’ve learned about this process and express it in an educated manner. I feel embarrassed even trying, but I hope that you’ll still get a feel for what this is all about.

The Vertical Bench

There are two main test benches used in electrical integration. The first of these is known as the vertical bench.

The vertical bench looks like a cross between a dismembered car and a telephone switchboard. It’s based on a rack system that has all of the car’s components attached to it. Look closely in the photo above and you’ll see several different radios, climate control, rear-seat video screens, door handles, etc.

Here’s a quick look into how complex things are these days – the front door handles alone are involved in more than 10 different electrical systems within the Saab 9-5. And to think there was a time when all you did was unlock the vehicle with a mechanical key and step inside! Today, with passive entry, you do less work but the car does a lot of the work for you and that work is planned and tested here at electrical integration.

Engineers are able to wire up the system and test all of these components as if they were wired up inside the vehicle itself. The ‘switchboard’ type setup means that they can test different configurations easily by unplugging or plugging in different components as needed.

As you know, Saabs are sold in over 50 countries around the world and the equipment list varies from country to country. What you may not know is that the performance of some electrical items can vary from country to country as well, because of market-specific environmental or climatic conditions. The sensitivity levels of some light- or moisture-based sensors, for example, can vary between more humid climates and dry climates. Saab are able to test all manner of configurations on the vertical bench and adjust/exclude/include equipment as they go.

As you can see from the photo below (the same bench as above, but photographed from behind), everything is hooked up to this system, from the sunroof and speakers to the exterior lighting system. This vertical bench is for the Saab 9-5 and they’ll keep this bench operational and updated as long as the vehicle is on the market.

Keeping this bench operational is essential because any changes that are made to the Saab 9-5 from model-year to model-year have to be run through electrical integration testing (which is just one of many change processes that has to be managed).

In the modern age that we live in, nearly everything has a sensor that feeds information back to a CPU, which helps to control the performance and functionality of the vehicle. These individual CPU’s then have to feed information to other CPU’s and the whole system has to work together, with lightning speed and consistent accuracy. Therefore, everything has to be tested and validated before changes can be passed as being suitable for market.

The A-Frame

The other type of test bench is known as the A-frame, even if it’s shaped more like a horseshoe.

The purpose of the A-frame is quite similar to the vertical bench, but there is a fundamental difference with the A-frame – it uses production-intent wiring and equipment. Where the vertical bench is used to test the integration and functionality of the electrical system, the A-frame does this AND verifies that the materials designed for use in the actual car are functioning as they should.

The horseshoe shape allows the engineers to set up the components in a manner that roughly replicates the layout of the car with a front, rear, left and right configuration. The A-frame in these photos is for the Saab 9-5 SportCombi and as you can see in the photos, there are plenty of real parts in there, including cooling system, gearbox and even under-floor setups.

Below you can see the sunroof from the Saab 9-5 as well as a rear-door opening robot for the SportCombi. It’s fascinating seeing so many of these moving parts outside of the vehicle, but still moving as if they’re in it. There’s almost a ‘Transformers’ type feeling to it.

The ‘front’ of the A-frame test bench vehicle has the radiator at the front and the transmission underneath, as well as the battery and other connection points. Look hard and you’ll even spot the steering rack in there and some front speakers (yes, the radio is tuneable). The blue container to the left is the airbag.

The four boxes you see stacked up on each other here are essentially artificial wheels so that systems involving the wheel rotation can be included in testing. Yes, the odometer on the A-frame dashboard does have a mileage reading on it 🙂


The integration process helps to test the operation of electrical functions, each of which is controlled by it’s own piece of software. This presents a challenge in itself for the development and manufacturing process, and electrical integration plays an important role in optimising the software package for manufacturing.

It’s rare at Saab that one particular vehicle on the production line has the exact same equipment and specification as the one before it. The downloading of software into the vehicle is matched to the vehicle’s specification and market, and is actually part of the manufacturing process on the production line, just like fitting the dashboard, seats or a set of tyres. A timeslot of 100 seconds is allocated for the complete download process and one of the jobs for the electrical integration team is to make sure that the software package remains compact enough to be downloaded within this time.

If you think about it long enough, you’ll really come to appreciate the work that these engineers do. Writing software for components, testing components, testing the integration of those components with others, adapting components and combinations of components for over 50 markets around the world and then making sure that the total software package for every configuration is small enough to be installed in the allotted time.

Thankfully, you shouldn’t ever have to think about the complexities of their job at all. All you should have to think about is how to use all this wonderful technology to make your drive safer and more relaxing.

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  1. Very nice insight.
    As I am a telecoms engineer I am used to integration setups.
    But these are different compared to racks full of cell phones for base station testing 😉

  2. I’m curious. One of the features I love about my 2004 Saab is its fiber optic data bus which I think was replaced by a GM-style wire bus around 2006. I think it was a feature that set Saab apart from more pedestrian volume brands. Is there any chance that it will return on future Saabs? I hope so, but I understand Saab’s difficult budget constraints might preclude that option for now.
    On another note, although not an EE, I have a bachelor’s degree in electrical engineering and have encountered difficulties in simple hobby circuits due to unexpected variances in components. I appreciate the great efforts Saab is taking to make their systems bullet proof.

    1. Although it’s certainly interesting technology, in practice it’s remarkably unreliable for an automobile, hence the replacement.  I also have a 2004 9-3 with the optical bus, and it’s by far one of the worst features of the car.  The complete o-bus failure that occurs with the nearly certain failure of AMP1 (due to unfathomably bad placement) is simply ridiculous.

      1. I don’t think the AMP1 placement is so bad, hard to find ventilated spaces in a car, but the the AMP1 itself may not be hardened against moisture well enough. Your comment about the complete o-bus failure is utter nonsense. The AMP1 will not take down the optical bus. Just turn the radio off as I did when I heard extreme popping from the speakers. Fortunately, my AMP1 was okay after drying for a day.

      2. My AMP1 failed and caused my battery to drain time and time again until I figured out that it was the amp. 
        The optical bus may be cool, but was a unnecessary waste of money for Saab. I hope Saab is more wise these days about what to develop and what to buy.

  3. What a great post! Thanks to Saab and Swade. I wonder if other car manufacturers let their fans come behind the scenes like this?

    I had no idea integrating different systems was this complex. And this is probably just a small portion of all the work that is being done! I will think about the engineers next time I open my door! 🙂

  4. Great stuff! Looks a bit like a DIY workbench. I wonder if Toyota, for instance, has the same approach. Hopefully, the stations are already set up for the next 9-3.

  5. Jeeeeses, this is so good to read. I do like reading thisstuff. Thank you Swade

  6. Great article! I had no idea how complex this is. Thank you Swade giving me an insight, I enjoyed it very much.

  7. You don’t fool me! All the “work” being done at those benches is playing Need for Speed. The monitors seems a bit undersized though 🙂 

  8. Fascinating. I trust you will keep us entertained for years to come with all of the ins and outs of how Saab does its thing.

  9. Great post.  Really amazing the technology in cars these days….and they need to be reliable for a long time.  I always marvel at how complex my 9-5 is and how reliably it all works.