ECM TSM/TSSM and SPEEDO lessens learned

[JHCHOPPERS]

We just finished a 2006 HD EFI bike project. The bike does not have the OEM SpeedO, or any after market SpeedO, and the fuel pump was mounted on the bottom side of the tank. We did a lot of research during the build to understand how the EFI System works. There are many different opinions from HD Dealers and Experts on the web on what you need to make the bike run. Now that our project is completed, I wanted to share the things we learned during this build. The ECM, TSM/TSSM and SpeedO all communicate over a serial bus. The SpeedO does NOT have to be installed for the bike to start and run. The SpeedO sends current speed information to the ECM, so the ECM can adjust the idle RPM vs rolling at 30 MPH and pulling the clutch in and keeping the RPMs a little higher under the anticipation of engine load during for the next shift of gears. The TSM/TSSM controls the turn signals based on the SpeedO sensor data sent from the SpeedO. If the SpeedO is not connected to the serial bus, the TSM/TSSM will not automatically cancel the turn signals when the current speed changes. NOTE: If you choose to install and after market SpeedO (ie Dakota Digital or others), the turn signals and RPM adjustment features of the OEM Speedo will not work. As these after market SpeedOs (the ones we looked at) do not connect to the Serial Bus and can not communicate the Current Speed information to the ECM and TSM. Not a bike deal for custom bike. TSM/TSSM to ECM: We left the stock TSM installed on our project as it controls the turn signals and most importantly it will signal the ECM to shut down the fuel pump if the bike is tipped over using the Bank Angle Senor. If your bike has a key fob, then you have a TSSM instead of a TSM. The TSSM signals the ECM the OK to start when it detects the Key Fob. If the Key Fob is not detected by the TSSM, the TSSM will prevent the ECM from starting the bike. I am not sure if your need to TSM or the TSSM installed for your bike to start and run, my guess is that you would not need it. But I have not tested this theory. If your EFI bike has Spark at the plugs and the Fuel Pump runs while you are trying to start the bike, the ECM is trying to start the bike. If the Crank Position Senor is not detected by the ECM when trying to start the bike, the ECM will turn off the fuel pump. You can test this by unplugging the Crack Position Sensor and attempting to start the bike. There is NO Fuel Pump Pressure Senor. The ECM controls the fuel pump by timing only. During the start cycle when the RUN switch is turned on the ECM runs the fuel pump to prime the pump and build pressure to the injectors. You can hear the pump run for about 2 seconds or so. The pump does not run again until you press the START button and will continue to run as long at it detects that the Crank is turning. Fuel Pressure can be measured by removing the Fuel Supply Tube and threading on a pressure gauge and securing with the OEM Hose Clamp. The Fuel pressure while the pump is running should be between 55 and 62 PSI You DO NOT need the fuel gauge sending unit for the bike to run. It’s for the fuel gauge only, the ECM does not care about the fuel level. Just because it’s called a “Fuel Sending Unit” doesn’t mean it sends fuel. If the Temperature Senor is bad, the ECM may enter a flood mode. Where the injectors are not fired during the Start Cycle to clear combustion chambers. I hope this information my help someone else, JH

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[kngobra]

Nice...thanks!!