I have searched the forum and found some related links but not exactly what I am looking for. I have a 97 550 for which I would like to diagnose and remove one or more fault codes. I have two OBD scanners which have worked well in the past but do not recognize my 550. I have no others to test so I can not say it is, or is not, car specific. If possible, I would like to ask some questions to further my education and perhaps aid in the troubleshooting. The OBD connector is populated with chassis ground on pin 4, ISO 9141-2 K line on pin 7, OEM specific on Pin 13, ISO 9141-2 L line on pin 15 and unswitched power on 16. Does the Ferrari proprietary SD2 use the pin 13 connection? Is the ISO 9141-2 K line normally pulled high by the Bosch ecu when there is no connection on the OBD2 port? My pin 7 is not pulled high when the key is on. If it is normally, then I need to go looking for an open towards the ecu. Does anyone understand ISO 9141-2 sufficiently to know if both the K and L lines are required for communication? I tried the "fix it" cable that moves pin 5 to pin 4. All this succeeded in doing was not supplying ground to both my OBD2 scanners and thus they would not power up. I have assumed that, if my scanners are using 5 for ground, they do not need ground present on pin 4 as well to communicate. Does that sound reasonable? Any help would be most welcome. I refuse to take my car to a dealer as it will surely result in a $10K plus bill as they replace the cats and O2 sensors! I would rather re-layout our fuel control to directly replace the Bosch units than turn the car over to a dealer. I have asked an independent with an SD2 to scan the car for codes but was in hopes I could solve the problem myself and learn a little something along the way. Thanks!
There appears to be connectors just at both ecus for the ISO 9141-2 K and L lines. I have verified that the left ecu's connector is connected and thus that ecu is attached to the in cabin OBD2 connector. I assume the right bank ecu, which appears to be the master fuel control of the two, is in the passenger side kick panel. The next step is to verify that its connection with the OBD2 connector is good. Does anyone know if the SD-1 (or SD-2) is noramally connected directly at the ecu? (as opposed to the OBD2 connector). These connections at the ecu are labled diagnostic connection.
I am not that well versed in the OBDII plug and pins, but there is an open recall on pretty much all Ferraris from 1996 to 2004(?). Take it to the dealer and they will update your plug and ADD one additional grounding pin on the plug. I or someone else posted the recall notice and actual factory repair documents (with photos) on this website. Okay I checked, here you go: http://www.ferrarichat.com/forum/showpost.php?p=136457100&postcount=13 Looks like you want a ground on pin 5 AND pin 4.
The K and L lines are indeed supposed to be pulled high. If your OBD2 scanner will not work on your 550, then check to make sure these line go from zero volts to 8V plus when you switch the key on. Mine did not. I followed the wiring harness diagram back to a connector just at the ECUs. This is apparently where the dealership attaches the SD-2. The left bank was connected, but the left bank is not the master ecu and thus does not have pull up resistors (or may not even talk on the IOS 9141-2 bus). The right bank's connector on my car was not connected to the car harness and thus the lines were not making it to the OBD2 connector. I unplugged the left banks L/K connector from the car harness and plugged the right bank in. I now had 8Vs on pin 15 of the OBD2 connector when I switched the car on and my scanner works just fine. The 97 550 US is OBD2 compliant and scanners work!!!!!!!!!
Thanks for the link and for posting the recall. There are people selling "fix it" cables on the net which basically move the ground pin over. I bought and tried one of these cables and it only managed to deny my OBD2 scanner of ground and thus it would not power up. Having ground on both pins 4 and 5 would not have helped my particular situation. For reference, the Harrison R&D scanner does not require ground on both pins and will work fine with the standard (or non-standard as the case may be) Ferrari wiring. All you have to do is check that pin 15 goes to 8V plus when you switch on the ignition. If it does not, check the SD-2 connection point on the right bank ecu (passenger side kick pannel). There is a mating male/female three pin connector coming just off the main connector to the ecu. If these are not connected to each other, the last person that used an SD-2 neglected to reconnect the K and L lines to the main car harness and thus no connection from the ecu to the OBD2 connector in the drivers foot well. I simply re-connected this pair, verified the 8Vs plus on pin 15 of the OBD2 connector and ran the Harrison R&D scan tool to check and clear the errors. Any ISO 9141-2 capible (ie not CAN bus) scan tool should work just fine; I just happened to use the Harrison tool. I have not tested a lot of tools and thus can not speak to the need for chassis ground and signal ground to both be present at the OBD2 connector (the Ferrari recall).
