Technical CAN Bus, body computer & C.

[got-nothin-better-to-do]

Ok are you ready for this, seems like a lot but here it goes...

I've been doing a lot of research on the matter, and it appears that OBD2 (on-board diagnostic version 2) is the same as EOBD (european OBD), and is forced on all petrol cars from 2001, and all desiels from 2004. The 16 pin connector for OBD2 is normally designed to be within easy reach of the driver, and on the MK2 puntos should be beneath the fuse box. On the older puntos, there is a three pin connector by the ECU in the engine compartment. It is possible to use an adapter to make it accept the 16-pin configuration, however it will only be OBD, not OBD2. This is done by connecting one of the pins (the ground pin) to pins 4 and 5 on the ODB connector, another one (the k-line) to pin 7 of the OBD connector, and the last one (L-line) to pin 15 on the OBD connector, and you will need to supply +12v from the battery (it is best to fuse it!) to pin 16 on the ODB connector. From what I can gather, OBD2 is backwards compatible to OBD, but you will not have the full functionality. OBD2 supports communication to about 6 different standards, including CAN bus and K/L line. Aftermarket devices can be used to read and clear stored error codes, turn off the engine warning light, and view sensor data in real time. I believe that the OBD on the older puntos will only be able to read and clear the stored error codes. With OBD2 there error codes should be generic, e.g. a P1403 error should be the same on every car, but there are some manufacturer specific codes, which will need to looked up. With OBD each manufacturer, and quite frequently, different models by the same manufacturer will use different codes specific to each model, so it is harder to find the codes. They are out there, so you won't need to ask Fiat, but they are a lot harder to find.

Hope this helps.

 

[got-nothin-better-to-do]

Oh and another thing, there is some free software free reading from OBD2 called OBD Gauge, and supports Windows, Pocket PC and Palm. You will need to get an adapter to convert the OBD2 port signals to ASCII strings, the same goes for all this software if to be used on a PC. Generally you should go for a serial one, as long as you computer/pda has a serial connector/cable as this has better compatibility, otherwise there is a bluetooth version, which utilises a virtual COM/serial port, or failing that USB. I haven't tried it yet, but I am hoping to get an adapter soon, and try it on an '04 Punto and a '97 Punto, and will post the results here somewhere.

 

[reddy4bed]

Done some soldering on the MK1 some time back and made up interface and wrote a small program to talk to the ecu. (IAW16F). The Marelli info which is on the web in several places lists the few commands to interogate the ecu and read back the data. Only did it on the bench though, but it all seemed to work ok. It operates in duplex ie one line out and another back with 0-+13v logic.

 

[mzhussein]

i know old thread, but was hoping for a hand, i bought an EOBD reader U480 to be specific, i followed instructions to convert 3 (old punto) in to 16 pin (new standard), but the U480 device just gives a read error, just wanted to pick someone brains, cos i realy need to know what this fault code is.