in this thread: Using oscilloscope on CAN bus.Door locked solid the OP stated he was trying to read

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in this thread: Using oscilloscope on CAN bus.Door locked solid the OP stated he was trying to read some data off the CAN Bus in his car, a 98 B5 in the UK. I replied probably in a rude fashion (as I am wont to do on occassion - tact and diplomacy are not always my strongest suit in a textual format like this one) and told him and a couple of other folks that there was no CAN Bus on B5 models vin number look up - to which they replied BS and cited "sources" supporting their claims (a Haynes manual is *not* a good source, guys - a Haynes vin number look up manual on our cars has more bad data than good), and I argued back, and then got shouted vin number look up down by a couple more people. another source cited was Ross-Tech's website - now that's a source I can dig into, cuz Uwe Ross knows his stuff. I know I'm old, and my brain might be reminicent of swiss cheese upon dissection, so my memory might be suspect at times; so, I did some digging. here's what I found... clearing up CAN vs non-CAN Bus. CAN stands for controller area network. the bus is the vehicle bus that allows for exchange of info via microcontrollers without one centralized controlling station. the data rate is as high as 1 MB/sec, and that's loads of info in near real time for a car. for the implementation VW uses, they throttle the data to what appears to be half that rate (500KB/sec). Ross-Tech does not say all of our cars have CAN Bus. from this link on their site , it states that B6 and newer models have it, and not older ones. I wasn't totally satisfied with that answer, since I asserted earlier that B5.5 models had CAN, but not B5s; therefore, vin number look up I did a little more digging on their site. having been here for as long as I have, and remembering vin number look up how many folks had a problem with after-market radios and having K wires put at +12 volts due to the new radio (and dealers saying their cars couldn't be scanned because of it) reminded me of it. the K wire was/is used for ODB-II diagnostic reads using the ISO-9141 interface requirements on B5 models, and the data rate was/is 10.4KB/sec - much slower than the CAN Bus. the newest vin number look up CAN Bus international standard is ISO-11898, the older CAN Bus is ISO-15765, vice the previous ODB-II interface (ISO-9141) using just the K wire. VW used the same connector vin number look up specified by international standards to implement ODB-II physical interfaces for a reader. from this page on Ross-Tech's vin number look up site , info is provided regarding the K wire (but not much). the important take-away is that aat some point during the B5 production years, VW decided to include radio diagnostic data into the data OBD-II colleected, and ran the K wire to the radio; after-market radio installations vin number look up shorted the K wire to +12 volts, rendering it impossible to get any diagnostic data off the ECU, etc. at the bottom of the previously linked page in my previous paragraph above, it discusses the instantiation of CAN Bus into radio diagnostics and shows the connectors for CANBus for B5.5 models. the only thing I know of on the B5.5 models that uses CAN Bus is the radio, but I might be wrong there. the easiest way to tell is to hang an o-scope off the K wire on a B5.5 and see if there is data on it while pulling codes... Lastly, discussions of K wire-based OBD-II diagnostics can be read about here: On-board diagnostics - Wikipedia, the free encyclopedia and scroll down to "OBD-II diagnostic connector" to see the pin-outs (yes, the ODB-II connector also has CAN Bus pinouts dedicated to it, but B5 models did not use it then, only the K wire) and again on the previously linked page on Ross-Tech's site, Ross-Tech: VCDS: Afterrmarket Radio Problem - it's pretty clear to me that all vehicle disgnostics went thru the K wire and not from a CAN Bus, as it did not exist in Passats then. to wit: ISO 9141-2: This protocol has an asynchronous serial data rate of 10.4 kBaud. (Jay's note - baud = bits/second) It is somewhat similar to RS-232; however, the signal levels are different, and communications happens on a single, bidirectional line without additional handshake signals. ISO 9141-2 is primarily used in Chrysler, European, and Asian vehicles. pin 7: K-line pin 15: L-line (optional) UART signaling K-line idles high, with a 510 ohm resistor to V batt The active/dominant state is driven low with an open-collector driver. Message length is restricted to 12 bytes, including CRC for the older members here, the VAG-COM cables we used to use were RS-232 cables vin number look up that plugged into the RS-232 port on our old Windows-based PCs on one end, and the O