Vehicle Speed Shows 5 km/h while standing still

Eric · Jun 18, 2017

I'd do a physical request to the trans (address 7E1, response should be at 7E9) with PID 0x0D. Only the trans will respond. As for the source of what it responds, I don't know. If I were in VAG's shoes, I certainly wouldn't bother with software to independently compute vehicle speed from the output shaft speed (which requires the transmission be coded for the various wheel diameters in all its applications), I'd read it over CAN just like the ECM does. But then again, I'm French, not German

The good news is you should be able to tell right now, by using the OBD2 mode of VCDS while at speed. That should get you both speed from the engine and speed from the DSG, and let you decide if what you get from the DSG is worth rebroadcasting.

da40flyer · Jun 18, 2017

Eric said:
I'd do a physical request to the trans (address 7E1, response should be at 7E9) with PID 0x0D. Only the trans will respond. As for the source of what it responds, I don't know. If I were in VAG's shoes, I certainly wouldn't bother with software to independently compute vehicle speed from the output shaft speed (which requires the transmission be coded for the various wheel diameters in all its applications), I'd read it over CAN just like the ECM does. But then again, I'm French, not German The good news is you should be able to tell right now, by using the OBD2 mode of VCDS while at speed. That should get you both speed from the engine and speed from the DSG, and let you decide if what you get from the DSG is worth rebroadcasting.

With VCDS at speed, and without my additional coding in my can module calculating speed, ECU shows fixed at 5 km/hr and the DSG vehicle speed shows actual vehicle speed in km/hr.

I just tried 7E1 and response was indeed 7E9 with speed showing correctly! Well, at least from the cursory look at the data so far.
This may be the answer to my problem... Thanks Eric!

Jack@European_Parts · Jun 18, 2017

I love it when a plan comes together...........

da40flyer · Jun 21, 2017

That appears to have done the trick! We coded in a request for the DSG vehicle speed and then rebroadcast it out as the ABS wheel speed. Seems to work well. Will know better once I get her back out on the track, but the street testing seems to work just fine...

Thanks again everyone!

da40flyer · Jul 13, 2017

@Eric, Do you happen to know the can message request and response to get the DSG Oil Temp? I'd like to be able to display that data on my dash.

Thanks,
David

Eric · Jul 13, 2017

Does it display a temp from the transmission in OBD2? If not, I'll need a debug file from reading the trans temperature in VAG mode. Let me know which one applies.

da40flyer · Jul 13, 2017

Eric said:
Does it display a temp from the transmission in OBD2? If not, I'll need a debug file from reading the trans temperature in VAG mode. Let me know which one applies.

It does not. I can only see the transmission temp via a request in VCDS.

Eric · Jul 13, 2017

OK; set options->debug level to 1024; save, go directly to the transmission and read the temperature there. Don't do anything else which would complicate my life

Close the session and VCDS gracefully, and send me DEBUG-02.DLM found in the Debug subfolder of VCDS. We'll take this in private from that point, but there's a chance you may not be able to make this work depending on how simplistic your embedded CAN logic is.

golfi_vend · Jul 13, 2017

Don't make it private

. It is very intresting read.

jeroenveer · Oct 26, 2017

If i send out a request at 7E1 i do not get a reply from the DSG, VCDS does connect to it over CAN.
Any ideas?

Vehicle Speed Shows 5 km/h while standing still

Eric

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da40flyer

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Jack@European_Parts

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da40flyer

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da40flyer

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Eric

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da40flyer

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Eric

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golfi_vend

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jeroenveer

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