SeaDoo DESS Key Security

As it relates to SeaDoo and Sport boats, there are differences as to what component in the ski manages DESS key security.

For all carbureted skis with DESS key security, the MPEM manages the CDI function, controls DESS key security, and is the electrical distribution and fuse center for almost all electrical functions. There are a couple of early exceptions where BRP utilized a separate CDI box in addition to the MPEM.

With the introduction of RFI (Real Fuel Injection) in 1998, SeaDoo changed its control strategy, which resulted in splitting the control management functions into two separate modules: the MPEM and a new separate ECU produced by Bosch. The ECU is responsible for fuel injection functions, while the MPEM maintains control of DESS security and electrical distribution and fusing. If you have ever seen the MPEM on an RFI Ski 2004 or earlier (not including the 3D), you will notice it is significantly deeper than other MPEMs. This is because the ECU is mounted inside a large plastic box, with the MPEM being the front cover or lid of the box. If you remove the MPEM cover that is retained with four bolts, you will find the ECU bedded in foam for shock protection behind it. While only BRP knows the exact strategy that drove this decision, I suspect it was to outsource engine management engineering for fuel injection. One real drawback to this strategy was the cost of the two separate modules. If you need to replace both modules, it basically doubles the cost of an MPEM used on a carbureted ski.

The MPEM utilized on DI (Direct Injected) skis introduced in 2000 includes the same functionality as the carbureted skis but also includes the engine control management functions required for fuel injection. It’s odd that BRP went back to an “all in one” control strategy on this ski, given the decision on the RFI in 1999. I believe this was a cost reduction for the RFI solution, and they partnered with Orbital Injection to co-develop the direct injection engine management function.
Introduced in 2002, 4-TECs brought yet a different control strategy to SeaDoo and Sportboats. Originally the ECU was manufactured by Siemens and later Bosch. The Bosch ECU was introduced with the iControl platform starting in 09 with the iS models. The MPEM used on the early 4-TEC skis primarily only manages electrical distribution and fusing. Other than some internal differences, every 4-TEC MPEM is the same. In 2007, the MPEM was eliminated on most models as a non-serviceable encapsulated control and was replaced with a lower-cost fuse and relay bus with replaceable components. DESS key security and programming are managed by the ECU in 4-TECs, not the MPEM.

SeaDoo completely changed the ECU with the introduction of the iS in 2009 and significantly increased the complexity of the subsystems in the Ski. With the iS design, the throttle iTC, the VTS trim, iBR brake, gauge cluster, and iS suspension controls all communicate with the ECU as well as each other over SeaDoo’s CanBus system. They call this new control system iControl. All 2012 SeaDoos now include iControl. Below is an excerpt from BRP on iControl: iControl is advanced watercraft technology that seamlessly integrates a host of new features and benefits, such as Intelligent Throttle Control (iTC) and iBR, to give the rider more control than ever before.

• NEW Sport/Touring Mode so operators can choose between Sport for instant throttle response or Touring for progressive throttle response
• On-water braking for on-demand stopping in half the distance of a conventional PWC
• Start in neutral to prevent the PWC from moving on start up
• Cruise control to set and maintain a constant speed
• Slow Speed Mode for the ability to adjust and set idle speed from 0 to 7 mph
• Learning Key that the owner can program to limit the speed and control the amount of acceleration
• iControl includes a more accurate GPS-based speedometer

iTC operates electronically, with no cables, so the throttle works progressively, with an effortless touch. iTC offers more precise engine calibration, improves fuel economy, and lowers overall operating costs.