1999 no ODB2 data
#11
11-26-2015, 08:50 AM
Resolved
I got the new to me (meaning used) TCU and swapped it in. That appears to have resolved all my issues.
I need to put everything back together and test it all again, but it all looks and works fine. The Tiptronic doesn't shift in manual mode but that is likely a broken or missing magnet since I get no codes and everything else is working fine.
I had to gather the troubleshooting steps from several sites in order to track down the issue. The frustrating part is that there is no good procedure documented for fixing no data from the OBD2 port. Even in the Bentley (admittedly I don't have the exact one for this car) there isn't really anything about K-line issues. Without any diagnostic codes it's very hard to even know where to start.
For anyone going through this issue here are the steps I took:
1. Try to get codes from OBD2 port. No data in my case.
2. Test voltage at OBD2 port between pins 4 (GND) and 7 (K-line) with the key on. If you get <9V you are good. Over that there is more to check. Mine was fine.
3. Pull the radio since that is easy.
4. Test resistance of K-line between radio (pin 3 of black connector) and OBD2 port pin 7. This value should be fairly low as it should just be the wire resistance between the radio and the diagnostic port. Mine was 195-196 ohms which is much more than wire resistance. If it's high like mine or open then you have a problem someplace - likely with another module on the bus.
5. Start eliminating modules that use the K-line until you get readings (and hopefully data) that are more normal. The ABS module appears to be a prime culprit. I eliminated mine by pulling the fuse for the ABS but with a bad module it's possible even without power there could be a short to ground or similar that could cause no data on the K-line. So actually disconnecting the modules one at a time is probably the best procedure. In my case since my Tiptronic was in fail-safe mode I next went to the TCM/TCU and eliminated that. That gave me normal function on the OBD2 port with no codes other than not reading the TCU. Thus I replaced the TCU and am back in business.
If you have Vag-Com/VCDS I believe it will tell you more about your K-line function. However, in my case I believe all it would tell you is that the K-line wasn't functioning right. So still not much help. If somebody cares to elaborate please do. My next purchase will be VCDS and a cable.
Hope this helps anyone that falls into the same pit I did.
I need to put everything back together and test it all again, but it all looks and works fine. The Tiptronic doesn't shift in manual mode but that is likely a broken or missing magnet since I get no codes and everything else is working fine.
I had to gather the troubleshooting steps from several sites in order to track down the issue. The frustrating part is that there is no good procedure documented for fixing no data from the OBD2 port. Even in the Bentley (admittedly I don't have the exact one for this car) there isn't really anything about K-line issues. Without any diagnostic codes it's very hard to even know where to start.
For anyone going through this issue here are the steps I took:
1. Try to get codes from OBD2 port. No data in my case.
2. Test voltage at OBD2 port between pins 4 (GND) and 7 (K-line) with the key on. If you get <9V you are good. Over that there is more to check. Mine was fine.
3. Pull the radio since that is easy.
4. Test resistance of K-line between radio (pin 3 of black connector) and OBD2 port pin 7. This value should be fairly low as it should just be the wire resistance between the radio and the diagnostic port. Mine was 195-196 ohms which is much more than wire resistance. If it's high like mine or open then you have a problem someplace - likely with another module on the bus.
5. Start eliminating modules that use the K-line until you get readings (and hopefully data) that are more normal. The ABS module appears to be a prime culprit. I eliminated mine by pulling the fuse for the ABS but with a bad module it's possible even without power there could be a short to ground or similar that could cause no data on the K-line. So actually disconnecting the modules one at a time is probably the best procedure. In my case since my Tiptronic was in fail-safe mode I next went to the TCM/TCU and eliminated that. That gave me normal function on the OBD2 port with no codes other than not reading the TCU. Thus I replaced the TCU and am back in business.
If you have Vag-Com/VCDS I believe it will tell you more about your K-line function. However, in my case I believe all it would tell you is that the K-line wasn't functioning right. So still not much help. If somebody cares to elaborate please do. My next purchase will be VCDS and a cable.
Hope this helps anyone that falls into the same pit I did.
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