BMW April 2022

ADAS “The process is to perform four-wheel alignment first and ADAS calibration second.” Advanced Driver Assistance Systems (ADAS) cover almost anything that alerts a driver to obstacles head or behind the vehicle whilst driving. The main components can include any or all of the following:

Ultrasonic sensors

LiDAR (Light Detection and Ranging) sensor

RADAR (Radio Detection and Ranging) sensor

C-MOS (Complementary Metal Oxide Semiconductor) camera.

All of these systems are undergoing continuous improvement, so that even in a single model life span the ADAS can be upgraded. Yet, depending on the price-point of the new vehicle and the ‘deal’ made for purchasing systems built into that new vehicle, brand-new models can feature what is effectively technology from some time ago.

The bottom line is we cannot assume anything. We have to use reliable evidence from the vehicle under repair.


When a vehicle is built the process ensures the suspension and steering are nominally aligned relative to the vehicle longitudinal centre line, using the values set by the ride and handling engineers. The end of line checks would include suspension geometry, but in the knowledge adjustments are infrequent because of the jigs used to build up the suspension as well as the body control critical dimensions. The ADAS is then built into a body structure with known tolerances and supported by suspension steering also which has known tolerances. During the end of line whole vehicle software download, the systems are checked – this includes ADAS.

Let’s consider what happens once the vehicle leaves the factory

Every single wheel rim impact has the risk of altering the suspension geometry, and this is easily checked both before delivery and during the vehicle’s life. However, unlike situations from before 2001 (the advent of the very first system we would call today ‘ADAS’), there’s more to four-wheel alignment than just making sure the vehicle tracks true. ADAS relies on the vehicle bodyshell and suspension system being correctly aligned, since until very recently the sensors could not automatically compensate for misalignment.

Diagnostics at the heart of everything

The vehicle which is in your shop ready for repair may have all, some or no ADAS sensors fitted. So, how do we check this? One way is part of the pre-scan routine, to see what the diagnostics reports. This will flush out sensor malfunctions which may not be caused by the impact, which will prevent financial claims after the repair is completed. The other way is to check via the vehicle manufacturer web site, but not all manufacturers detail the options fitted to a specific vehicle by VIN.

All of the sensors work together in a network, so altering or repairing one part of the vehicle may induce recalibration in an apparently undamaged area.

There is a priority after the repair is completed:

  1. Perform four-wheel alignment, and adjust accordingly.
  2. Perform ADAS calibration.
  3. Check the diagnostics system at the end of the process.

The forward-facing sensors have long, narrow sensing areas, which means if they are not aligned to the vehicle longitudinal centre line, then they end up scanning irrelevant data. If the sensor(s) are not aligned correctly, then the detection range in the direction of travel will be reduced.

One example: A robot applies bonding agent to a windscreen an One example: A robot applies bonding agent to a windscreen and fits it to the vehicle shell during manufacture. In the aftermarket humans apply the bonding agent, and then place the windscreen onto the body. The forward-facing camera is fitted to the inside of the windscreen, the position it had in manufacturing might be different to the post-repair position – so it needs to be re-aligned

Calibration, not forgetting diagnostics

Some vehicle manufacturers require an elaborate array of boards, four-wheel alignment sensors – which are not the same as used for four-wheel alignment – and more. Why? When a vehicle is built, the body, suspension and ADAS are all aligned. In repair, this has to be re-verified, to ensure the diagnostic system knows where the vehicle centre line is, and to aim the sensor accordingly. On older systems the sensor aiming is in part via mechanical adjustment, but for all systems the diagnostic tools are the only way to ensure the system is ‘awake’ and functioning properly. There are three types of calibration:

  1. Static

The vehicle has to be set up inside a dedicated test facility which has a floor area typically between 6 and 8 vehicle repair bays. There are some criteria in addition, especially for the CMOS camera:

The floor must be absolutely level with no steps / slopes.

There should be no drafts.

The light should be bright and even, so elimination of shadows is important.

The work space should not be used as an access route to other parts of the shop, especially during a calibration sequence.

There should not be a dramatic colour contrast between the walls / floor / ceiling. Typically, shades of mid-grey are used for the floors, walls and ceiling.

Once the vehicle is in the bay, the ride height needs to be checked and if possible, adjusted. The test equipment needs to be set up for the ADAS on each end of the vehicle, and there will be target boards which will have features the forward-facing RADAR and windscreen camera can recognise, which need to be set up at a specific location ahead of the vehicle.

The calibration is achieved by running a test on the diagnostics system, which allows it to recognise modules which have been refitted or to introduce new, replacement modules to the vehicle. Once the calibration process has been run the diagnostic system will acknowledge if it has been successful, or alert if the process should be repeated.

It is not uncommon to have different set-ups for front RADAR, windscreen camera and rear RADAR.

  1. Dynamic

This first appeared when Ford Premier Group (Volvo, Jaguar Land Rover, Lincoln) and Ford of Europe struck out in 2008 with a test drive process and has gained traction since.

After an initial set up which ensured the sensor was upright, which sometimes involved basic mechanical adjustment, the diagnostics system is used to recognise modules which have been refitted or to introduce replacement modules to the vehicle. With the diagnostics system still connected the vehicle is taken on a test drive to ensure the system recognised different road markings, types of vehicle and more. This process usually has to be completed between 64 and 96 km/h.

The programme will freeze the calibration should the vehicle be driven too slowly or too fast, and resume once it is in the correct speed range. Similarly, the calibration will continue until the system has seen the required variations in road markings as well as types of vehicle. Whilst the calibration may take 10 minutes to perform, in real world traffic conditions the process might take much more time to complete depending on traffic conditions as well as possible road speed.

  1. Self-calibration

The first of these systems appeared on rear RADAR applications in 2017. The diagnostics system will allow the vehicle to recognise modules which have been refitted or to introduce replacement modules to the vehicle. Once this step has been completed, the ADAS sensor self-calibrates as the vehicle is driven – so the customer should be warned the blind spot detection system may not function fully, or the repair shop can road test until the calibration is complete. This can take around 30 minutes, depending on traffic conditions.

If for some reason the sensor is unable to calibrate, a warning light on the instrument panel will illuminate. This will require the diagnostics system to be used again to determine the fault and may involve replacing the sensor.

Self-calibration introduces a number of interesting challenges, such as warning the user that the full ADAS functionality will be restored within an hour or two of collection, if the shop has not completed this step.

Get to know the diagnostics tool

This is the most important aspect of the ADAS calibration process, because ADAS is fully integrated into the whole vehicle. It interacts with SRS, seat belts, window lifters, the brake system and even the powertrain. A malfunction in one area can flag as a fault in an apparently un-related area.

The diagnostics tool is the window from the outside world into the whole vehicle system, and that power is rarely used. However, with increasing vehicle sophistication there has never been a stronger need to understand how each system works, and how those systems work together, to help solve faults.

There are no ‘industry’ trends nor standardisation/agreement on ADAS sensor types, function or performance. This model specific chaos is likely to continue for some years, until the future becomes clearer. Until then, we have to work with what is available, be aware of new developments and use methods to assist in solving problems, car by car. The process, after repair is:

  1. Perform four-wheel alignment, and adjust accordingly.
  2. Perform ADAS calibration.
  3. Check the diagnostics system at the end of the process.

Building the future

The advent of partial autonomy, driven by the vehicle manufacturers, tier 1 suppliers and the roll out of 5G, may well be overstated – but as rearward facing ADAS comes into law alongside forward facing ADAS, we will see more and more sensor ‘self-calibration’. This will include the ability of a vehicle to marry suspension/body misalignment with ADAS sensor intelligence.

If there is one important lesson, it is this: assume nothing

Do not assume knowledge of ADAS on a vehicle from five years ago applies to the latest model.

Do not assume the latest model has the very latest ADAS technology – it might have brand new sensors, but these may be designs created more than a decade ago.

Use model specific manufacturer information to understand what is fitted where – and know a vehicle could be fitted with all possible systems, or not one.

Use the diagnostics tool. This is the route to success.

ADAS knowledge build-up is typical of the challenges facing our sector, yet these challenges place our sector in a strong position to capitalise on future economic growth which is now a certainty.

Auto Industry Consulting is an independent provider of technical information to the global collision repair industry via EziMethods, our online collision repair methods system. For more information please visit the website:


By Andrew Marsh