Electronics and Software Engineer

Project: Memory Seat Controller

For GM Holden MBS developed a Memory Seat Controller. This unit is used in the Holden Caprice / Statesman. When pressing the remote control of the vehicle, both driver seat and outside mirrors travel to a memorized position. No more adjusting seat and mirrors after someone else used the car.

To reduce the number of wires to the door, the seat module communicates with the outside mirrors via a one wire serial link. This also prevents wire-loom changes when new features are added to the system.

For Schefenacker Vision Systems (previously Britax Rainsfords) MBS developed the electronics for their smart memory mirror and mirror switch. This system is used in the same car as the seat controller. The electronics use Hall sensors and ferrite magnets to determine mirror glass position. This method is much more durable than potentiometers. Mirrors and switch also communicate via a one wire serial link.

Lear Seating was the seat supplier to GM Holden before they were taken over by Air International. For these companies MBS has built three different testers to support the memory seat product.

  • A bed-of-nail tester to verify and calibrate the memory seat module electronics
  • A functional tester to test the side cover assembly
  • A functional tester/ calibrator to test a complete memory seat

The bed-of-nail tester is used at the factory where the electronics are assembled. It consists of an in-circuit and a functional tester, which are both housed in in same test jig. The in-circuit tester checks every individual component and accurately pinpoints the location of any fault or bad solder joint. This makes rework very easy.

IC’s, relays and software are tested by a functional tester. Even the volume level of the beeper is measured at this stage.

The tester issues a serial number to every module and will log all test results. Full statistical process control is performed on every unit and every assembly run.

Due to the specific requirements, we have designed our own test jig in AutoDesk Inventor. This jig design is easily adapted to support other projects. It is locally made, reduces cost and is a better fit than an of-the-shelf import.

All 3 testers perform a functional test. Because they had so many things in common, only one PCB was designed. Placing the DIL switches into a different position, turns the circuit into another tester. This modular design makes it very easy to adapt this circuit to test target boards of other (future) projects. It is even capable of verbally passing on the error messages to an operator via a wireless head set if this makes product assembly more efficient.

For backup we made a spare tester which can do all 3 jobs.

Apart for the developing tasks, MBS also manages, and is responsible for the production of the memory seat controller.

Kevin Hooper, General Manager of Air International at the time, summarised his experiences of working with MBS.

MBS developed a number of different production testers. These testers were used in various stages of the seat production. The testers not only comprehensively test and calibrate the seat or seat sub-assembly but also made use of a test-pass-token system in which each tester passed on a test result message to the next tester. The result of this scheme, together with an excellent quality memory seat controller, is that over a period of 4 years, building thousands of memory seats, a Memory Seat controller has never caused a valid warranty claim.


MBS was to us a very creative and reliable developer / supplier. They manage their work professionally and have shown great care for detail. Their products have proven to be robust and of excellent quality.


Kevin Hooper
General Manager
Air International