749S Italian wiring

W

WesleyHalbe

New member
Hey Guys,

I have some minor electrical things that maybe you guys know more about. (I'm still a bit new in the world of Italian bikes)

1st.
I noticed that the voltage readout on my screen is quite low (around 12V). At first, I thought it would be just a cheap battery. Now I switched to a Li-ion battery (it starts amazingly now), but it still stays at 12V. What could be wrong? (I did test the charging system, and this works perfectly, gives 14.8V)
2st
I can't read out my ECU with the odb2 connector and de software. I tried everything, but I can't get a connection. (I do have a Power Commander 3 on the bike, former owner placed it.)
Any idea why? Maybe a bad connector from the ECU?

Thanks!
 
I have little expertise with electrics, Italian or otherwise, but I do know that you don't rely on the bike's screen to tell you voltages.

Check the voltage using a multimeter to determine whether your voltage is at the right level.
 
As for the voltage difference, probably down to resistance loss. Remember the 749 was launched in 2003. There is potential for resistance in a multitude of components between the battery and the dash with a bike that is around 23 years old. If meter checks show the battery is in good order, then all is well.
 
You say an OBD2 connector.
Ideally you should be using a VagCom 409.1 using the FTDI chip. (That also allows use with other software like Guzzidiag and TuneECU)
With a slight modification a WinChipHead CH341 can be used.
 
chrisw said:
You say an OBD2 connector.
Ideally you should be using a VagCom 409.1 using the FTDI chip. (That also allows use with other software like Guzzidiag and TuneECU)
With a slight modification a WinChipHead CH341 can be used.
Click to expand...
Clear, thanks!

To read it out myself, I probably didn't do it right but I also tried using one of those professional readers (after maintenance to reset the dash), sadly also no success with that one. That's why I'm a bit lost here.
 
Ducati diagnostics of this period are not OBD compliant. That is why OBD readers do not work.
Originally Ducati diagnostics were K and L line based (as on the 916 era of bikes).
This then moved to K line based, as on the 749/999.
It was found that the K line/L line and K line diagnostic systems could be communicated with by using commercially available USB leads like the 409.1 and using the below protocols enthusiasts were able to create software to work with the diagnostic system to read fault codes, reset service reminders and make adjustments/resets.
The system is based around ISO 9141-2 and KWP2000 protocols.

Dealer diagnostics on these era bikes were done with Ducati’s Mathesis system (later the DDS).
When Ducati moved to CanBus things had to change and it was found that ELM327 was able to process the CanBus diagnostic but new enthusiast software had to be created. (ELM327 can process both K and L Line but was not as reliable as the 409.1)
This is why there is the likes of JPDiag (for K line based) and Melcodiag (for CanBus based).
This may help
  • ISO 9141-2 = the physical/electrical communication standard (how bits travel over the K-line wire)
  • KWP2000 = the diagnostic protocol running over that link (the language the ECU speaks)
  • OBD2 = a standardised set of diagnostic services, fault codes, and data requests (a common vocabulary, mainly for emissions diagnostics)
  • ELM327 = an intelligent protocol translator/interface that converts simple PC commands into OBD2 and vehicle-protocol messages (ISO 9141-2, KWP2000, CAN, etc.)
  • VAG-COM 409.1 (KKL cable) = a relatively "dumb" K-line interface that passes serial data between the PC and the ECU with minimal interpretation
  • WinChipHead (CH340/CH341) = the USB-to-serial chip often found inside a 409.1 cable; it handles USB communication but knows nothing about OBD2, KWP2000, or Ducati diagnostics
To complicate matters, some of the newer Ducatis will communicate with commercially available OBD readers. I believe it is the Euro 5 models, but the diagnostics are limited.

✅ Read and clear engine fault codes
✅ View live engine data (RPM, coolant temp, throttle position, O2 sensors, etc.)
✅ Check emissions-related faults

Often not available:

❌ Service light reset
❌ Desmo service reset
❌ ABS diagnostics
❌ Suspension diagnostics (DES)
❌ Ducati-specific module coding

For anyone interested here is a YouTube video about the protocols. Remember those creating the Free Software were reverse engineering the ‘diagnostic device’. Whereas in this video a commercially available reader was used to help sniff the signals. That is why it is important to donate to those who have provided their work Free of Charge.


The upshot for you is that commercially available OBD readers will not work with your bike.
 
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